JP6729094B2 - Toner and image forming method - Google Patents

Description

The present invention relates to a toner and an image forming method.

Conventionally, an electrostatic latent image formed on a photoconductor is developed with toner to form a toner image, the formed toner image is transferred to a sheet, and the transferred toner image is heat-fixed. There is known an electrophotographic image forming apparatus that forms an image on an image. In such an image forming apparatus, in order to fix the toner image on the sheet by heat fixing, it is necessary to heat the toner to a high temperature to once melt the toner. Therefore, there is a limit to energy saving.

In recent years, a system for fixing with an external stimulus different from heat has been proposed in order to save energy during image formation, improve operability, and expand applicable media types. Among them, a photo-fixing system, which is relatively suitable for an electrophotographic process, has attracted attention, and a developer (photo-melting toner) softened by light has been reported.

For example, Patent Document 1 discloses a developer containing a binder resin, a colorant, and an additive, and the additive contains a compound that undergoes a cis-trans isomerization reaction by light absorption and undergoes a phase transition. ing. Further, in Patent Document 1, as a fixing method using such a developer, a toner image transferred onto a sheet is irradiated with light to melt a compound that undergoes a phase transition by light absorption, and then is irradiated again with light. Then, a technique of fixing the toner image on the paper by coagulating the compound is disclosed.

Further, Patent Document 2 discloses an image forming apparatus in which a developer containing a compound that undergoes a cis-trans isomerization reaction by light absorption and undergoes a phase transition is used. An example of such an image forming apparatus is an exposure apparatus that irradiates light toward a nip position, which is a position where a conveyor belt is sandwiched between a photoconductor and a transfer roller, when an image is formed on a recording sheet made of a transparent resin. An image forming apparatus provided with is proposed.

JP, 2014-191078, A JP, 2014-191077, A

However, the developers described in Patent Documents 1 and 2 have problems that productivity is low and image fixability is poor because the softening rate by light irradiation is not sufficient.

Therefore, an object of the present invention is to provide a means for improving the softening speed by light irradiation and the fixability of an image.

The present inventors have conducted intensive research. As a result, they have found that the above problem can be solved by a toner containing an azobenzene derivative having an alkyl group having a specific carbon number, and have completed the present invention.

That is, the present invention is a toner containing an azobenzene derivative represented by the following chemical formula (1).

In the above chemical formula (1), R is the same alkyl group or alkoxy group having 6 to 16 carbon atoms.

According to the present invention, means for improving the softening speed by light irradiation and the fixing property of an image are provided.

1 is a schematic configuration diagram showing an image forming apparatus 100 used in an image forming method according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram of an irradiation unit 40 in the image forming apparatus 100.

The present invention is a toner containing an azobenzene derivative represented by the following chemical formula (1).

In the above chemical formula (1), R is the same alkyl group or alkoxy group having 6 to 16 carbon atoms.

The toner of the present invention containing such an azobenzene derivative has an improved softening rate by light irradiation and is excellent in image fixability.

Although the details of why the toner of the present invention achieves the above effects are unknown, the following mechanism is considered. The following mechanism is speculative, and the present invention is not limited to the mechanism described below. In the following description, the azobenzene derivative represented by the above chemical formula (1) is also simply referred to as the “azobenzene derivative of the present invention”.

Azobenzene compounds are known to be materials that absorb light and soften from the solid state (optical phase transition), and the optical phase transition of azobenzene compounds occurs when the crystal structure collapses due to cis-trans isomerization. It is believed that Since azobenzene compounds generally have strong π-π interaction between molecules, an optical phase transition occurs only at the outermost surface of the compound. However, since the azobenzene derivative of the present invention has the same alkyl group or alkoxy group in the para-position of two benzene rings, the π-π interaction is weakened and the carbon chain of the alkyl group or alkoxy group is long to some extent. Therefore, isotropic (property to become liquid) is likely to occur. When the temperature is high, such as inside the image forming apparatus, the molecular mobility of the carbon chain of the alkyl group or alkoxy group of the azobenzene derivative increases, strengthening the π-π interaction between the azobenzene units and stabilizing the system. Try to figure out. However, if the azobenzene derivative of the present invention is irradiated with light to weaken the π-π interaction, the azobenzene derivative of the present invention tends to be isotropic, and becomes a stable liquid state at a high speed. Therefore, the toner of the present invention has an improved softening speed by light irradiation and can improve the fixing property of an image with a smaller energy.

Hereinafter, preferred embodiments of the present invention will be described. In the present specification, “X to Y” indicating a range means “X or more and Y or less”. In addition, in the present specification, unless otherwise specified, operations and measurements of physical properties are performed under conditions of room temperature (20 to 25° C.)/relative humidity of 40 to 50% RH.

[Toner composition]
<Azobenzene derivative>
The azobenzene derivative of the present invention is represented by the following chemical formula (1).

In the above chemical formula (1), R is the same alkyl group or alkoxy group having 6 to 16 carbon atoms.

When the number of carbon atoms of the alkyl group or alkoxy group used for R is less than 6, photophase transition is less likely to occur and the softening rate by light irradiation becomes slow. Further, when the alkyl group or alkoxy group used for R has less than 6 carbon atoms, some compounds are liquid at room temperature, and it becomes difficult to apply such compounds to toner. On the other hand, if the carbon number exceeds 16, it becomes difficult to synthesize the azobenzene derivative. The alkyl group or alkoxy group used in R preferably has 6 to 12 carbon atoms. When the carbon number is 6 to 12, the melting point of the azobenzene derivative is lowered, the softening speed of the toner by light irradiation is increased, and the fixability of the image is further improved.

Examples of the alkyl group having 6 to 16 carbon atoms used in R include n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group. Group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group and other linear alkyl groups; 1-methylpentyl group, 4-methyl-2-pentyl group, 3,3-dimethyl Butyl group, 2-ethylbutyl group, 1-methylhexyl group, t-octyl group, 1-methylheptyl group, 2-ethylhexyl group, 2-propylpentyl group, 2,2-dimethylheptyl group, 2,6-dimethyl- Branched alkyl groups such as 4-heptyl group, 3,5,5-trimethylhexyl group, 1-methyldecyl group and 1-hexylheptyl group;

Examples of the alkoxy group having 6 to 16 carbon atoms used in R include n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group. Group, linear alkoxy group such as n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-pentadecyloxy group, n-hexadecyloxy group: 1-methylpentyloxy group , 4-methyl-2-pentyloxy group, 3,3-dimethylbutyloxy group, 2-ethylbutyloxy group, 1-methylhexyloxy group, t-octyloxy group, 1-methylheptyloxy group, 2-ethylhexyl Oxy group, 2-propylpentyloxy group, 2,2-dimethylheptyloxy group, 2,6-dimethyl-4-heptyloxy group, 3,5,5-trimethylhexyloxy group, 1-methyldecyloxy group, 1 -A branched alkoxy group such as a hexylheptyloxy group;

More specific examples of the azobenzene derivative of the present invention include 4,4'-dihexylazobenzene, 4,4'-dioctylazobenzene, 4,4'-didecylazobenzene, 4,4'-didodecylazobenzene, 4,4'. '-Dihexadecylazobenzene, 4,4'-bis(hexyloxy)azobenzene, 4,4'-bis(octyloxy)azobenzene, 4,4'-bis(dodecyloxy)azobenzene, 4,4'-bis( Hexadecyloxy)azobenzene and the like.

As described above, the alkyl group or alkoxy group having 6 to 16 carbon atoms used in R may be linear or branched. However, a linear alkyl group or an alkoxy group is preferable from the viewpoint of having a rod-shaped molecule structure in which a light phase transition easily occurs.

The method for synthesizing the azobenzene derivative is not particularly limited, and a conventionally known synthesis method can be applied. For example, in the case of an azobenzene derivative in which R in the chemical formula (1) is an alkyl group, 4,4′-dialkylazobenzene is obtained by treating p-alkylaniline with manganese dioxide as an oxidizing agent in toluene. (See the following reaction formula (1)).

Further, for example, in the case of an azobenzene derivative in which R in the chemical formula (1) is an alkoxy group, if an alkyl halide is reacted with 4,4′-dihydroxyazobenzene in N,N-dimethylformamide (DMF), 4,4'-dialkoxyazobenzene can be obtained (see the following reaction formula (2)).

The azobenzene derivative may be used alone or in combination of two or more kinds.

<Binder resin>
The toner of the present invention preferably contains a binder resin. It is generally known that toner particles having a substantially uniform particle size and shape can be produced by using an emulsion aggregation method described below as a method for producing a toner. With the azobenzene derivative alone represented by the chemical formula (1), it is not possible to prepare toner particles by salting out in the emulsion aggregation method due to the molecular structure, but by using the azobenzene derivative and a binder resin in combination, Toner particles having a substantially uniform particle size and shape can be prepared by salting out in the emulsion aggregation method. Therefore, the toner containing the azobenzene derivative and the binder resin can be more easily applied to the electrophotographic toner.

As such a binder resin, a resin generally used as a binder resin constituting a toner can be used without limitation. Specific examples thereof include styrene resin, acrylic resin, styrene acrylic resin, polyester resin, silicone resin, olefin resin, amide resin, and epoxy resin. These binder resins may be used alone or in combination of two or more.

Among these, the binder resin is at least one selected from the group consisting of a styrene resin, an acrylic resin, a styrene acrylic resin, and a polyester resin from the viewpoint of having a low viscosity when melted and a high sharp melt property. Is preferable, and it is more preferable to include at least one selected from the group consisting of styrene acrylic resin and polyester resin.

The styrene acrylic resin and the polyester resin, which are preferable binder resins, will be described below.

(Styrene acrylic resin)
The styrene-acrylic resin in the present invention is formed by polymerizing at least a styrene monomer and a (meth)acrylic acid ester monomer. Here, the styrene monomer includes not only styrene represented by the structural formula of CH ₂ ═CH—C ₆ H ₅ but also those having a known side chain or functional group in the styrene structure.

Further, the (meth)acrylic acid ester monomer has a functional group having an ester bond in the side chain. _{Specifically,} CH 2 = CHCOOR (R is an alkyl group) other acrylic acid ester monomer represented _by, methacrylic acid ester represented by _{CH 2 = C (CH 3)} COOR (R is an alkyl group) A vinyl ester compound such as a monomer is included.

Specific examples of the styrene monomer and the (meth)acrylic acid ester monomer capable of forming the styrene acrylic resin are shown below, but the present invention is not limited to those shown below.

Examples of the styrene monomer include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene and p-. Examples thereof include t-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene and pn-dodecyl styrene.

Further, the (meth)acrylic acid ester monomer is typically the acrylic acid ester monomer and the methacrylic acid ester monomer shown below, and examples of the acrylic acid ester monomer include methyl acrylate and Examples thereof include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate and phenyl acrylate phenyl. Examples of the methacrylic acid ester monomer include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate. , Lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate and the like.

These styrene monomers, acrylic acid ester monomers, or methacrylic acid ester monomers can be used alone or in combination of two or more.

Further, the styrene-acrylic copolymer includes, in addition to the above-mentioned copolymer formed only of the styrene monomer and the (meth)acrylic acid ester monomer, the styrene monomer and the (meth)acrylic acid ester. In addition to the monomer, some are formed by using a general vinyl monomer together. The vinyl monomers that can be used together when forming the styrene-acrylic copolymer according to the present invention are illustrated below, but the vinyl monomers that can be used together are not limited to those shown below.

(1) Olefins, ethylene, propylene, isobutylene, etc. (2) Vinyl esters, vinyl propionate, vinyl acetate, vinyl benzoate, etc. (3) Vinyl ethers, vinyl methyl ether, vinyl ethyl ether, etc. (4) Vinyl ketones, vinyl methyl ketone, Vinyl ethyl ketone, vinyl hexyl ketone, etc. (5) N-vinyl compounds N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, etc. (6) Other vinyl compounds such as vinyl naphthalene, vinyl pyridine, acrylonitrile, methacryloyl Acrylic acid or methacrylic acid derivatives such as nitrile and acrylamide.

It is also possible to prepare a resin having a crosslinked structure by using a polyfunctional vinyl monomer. Furthermore, it is also possible to use a vinyl monomer having an ionic dissociative group in the side chain. Specific examples of the ionic dissociative group include a carboxyl group, a sulfonic acid group, and a phosphoric acid group. Specific examples of vinyl monomers having these ionic dissociative groups are shown below.

Specific examples of the vinyl monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester. ..

The method for forming the styrene acrylic resin is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. If necessary, a known chain transfer agent such as n-octyl mercaptan may be used.

When forming the styrene acrylic resin used in the present invention, the content of the styrene monomer and the acrylate monomer is not particularly limited, and the softening point temperature and glass transition temperature of the binder resin are controlled. It is possible to make an appropriate adjustment from the viewpoint. Specifically, the content of the styrene monomer is preferably 40 to 95% by mass, and more preferably 50 to 80% by mass, based on the whole monomer. The content of the acrylic acid ester monomer is preferably 5 to 60% by mass, and more preferably 10 to 50% by mass, based on the total amount of the monomers.

The method for forming the styrene acrylic resin is not particularly limited, and examples thereof include a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Specific examples of the oil-soluble polymerization initiator include azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators shown below.

Examples of the azo or diazo polymerization initiator include 2,2′-azobis-(2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile and 1,1′-azobis(cyclohexane-1). -Carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile and the like.

As the peroxide-based polymerization initiator, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2, 4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, tris-(t-butylperoxy)triazine and the like can be mentioned.

Further, when the styrene acrylic resin particles are formed by the emulsion polymerization method, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropaneacetic acid salts, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

The polymerization temperature varies depending on the type of monomer and the polymerization initiator used, but is preferably 50 to 100°C, more preferably 55 to 90°C. Further, the polymerization time varies depending on the type of the monomer and the polymerization initiator used, but is preferably 2 to 12 hours, for example.

The styrene-acrylic resin particles formed by the emulsion polymerization method may be composed of two or more layers made of resins having different compositions. In this case, the production method is as follows: A polymerization initiator and a polymerizable monomer are added to a dispersion liquid of resin particles prepared by an emulsion polymerization treatment (first-stage polymerization) according to a conventional method, and this system is polymerized. A multi-stage polymerization method in which the treatment (second stage polymerization) is performed can be adopted.

(Polyester resin)
The polyester resin is a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid component) and a divalent or higher valent alcohol (polyhydric alcohol component). The polyester resin may be amorphous or crystalline.

The valences of the polyvalent carboxylic acid component and the polyhydric alcohol component are each preferably 2 to 3, and particularly preferably 2 respectively, so that when the valence is 2 as a particularly preferred form (that is, dicarboxylic acid). The acid component and the diol component) will be described.

Examples of the dicarboxylic acid component include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid. (Dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18 -Saturated aliphatic dicarboxylic acids such as octadecane dicarboxylic acid; unsaturated aliphatic dicarboxylic acids such as methylenesuccinic acid, fumaric acid, maleic acid, 3-hexenedioic acid, 3-octenedioic acid, dodecenylsuccinic acid; phthalic acid, Terephthalic acid, isophthalic acid, t-butylisophthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-phenylenediacetic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, anthracenedicarboxylic acid, etc. Unsaturated aromatic dicarboxylic acid; and the like, and lower alkyl esters and acid anhydrides thereof can also be used. The dicarboxylic acid components may be used alone or in combination of two or more.

In addition, trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, and anhydrides of the above carboxylic acid compounds, or alkyl esters having 1 to 3 carbon atoms can also be used.

Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptane. Diol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecane Saturated aliphatic diol such as diol, 1,18-octadecane diol, 1,20-eicosane diol, neopentyl glycol; 2-butene-1,4-diol, 3-butene-1,4-diol, 2-butyne Unsaturated aliphatic diols such as -1,4-diol, 3-butyne-1,4-diol, and 9-octadecene-7,12-diol; Bisphenols such as bisphenol A and bisphenol F, and ethylene oxide addition thereof. Compounds, aromatic diols such as alkylene oxide adducts of bisphenols such as propylene oxide adducts, and derivatives thereof can also be used. The diol components may be used alone or in combination of two or more.

The method for producing the polyester resin is not particularly limited, and it can be produced by polycondensing (esterifying) the polyvalent carboxylic acid component and the polyhydric alcohol component using a known esterification catalyst.

As catalysts that can be used in the production of polyester resin, alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum, zinc, manganese, antimony, titanium, tin, zirconium, Compounds of metals such as germanium; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Specifically, examples of the tin compound include dibutyltin oxide (dibutyltin oxide), tin octylate, tin dioctylate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetranormal butyl titanate (Ti(O-n-Bu) ₄ ), tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; titanium tetra Examples thereof include titanium chelates such as acetylacetonate, titanium lactate, and titanium triethanolaminate. Examples of the germanium compound include germanium dioxide. Further, examples of the aluminum compound include polyaluminum hydroxide, aluminum alkoxide, tributylaluminate and the like. You may use these individually by 1 type or in combination of 2 or more type.

The polymerization temperature is not particularly limited, but is preferably 70 to 250°C. The polymerization time is also not particularly limited, but is preferably 0.5 to 10 hours. During the polymerization, the pressure inside the reaction system may be reduced if necessary.

When the toner of the present invention contains a binder resin, the content ratio is preferably in the range of azobenzene derivative:binder resin=5:95 to 80:20 (mass ratio). Within this range, the optical phase transition of the azobenzene derivative is likely to occur, and the softening speed of the toner by light irradiation becomes sufficient.

The toner containing the azobenzene derivative represented by the chemical formula (1) and the binder resin may have a single-layer structure or a core-shell structure. The type of binder resin used for the core particles having a core-shell structure and the shell portion is not particularly limited.

<Colorant>
The toner of the present invention may contain a colorant. As the colorant, generally known dyes and pigments can be used.

Examples of the colorant for obtaining a black toner include carbon black, magnetic materials, iron-titanium composite oxide black, and the like.Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. Can be mentioned. Further, examples of the magnetic material include ferrite and magnetite.

As a colorant for obtaining a yellow toner, C.I. I. Solvent Yellow 19, dye 44, dye 77, dye 79, dye 81, dye 82, dye 93, dye 98, dye 103, dye 104, dye 112, dye 162; I. Pigment Yellow 14, the same 17, the same 74, the same 93, the same 94, the same 138, the same 155, the same 180, the same 185 and the like.

As the colorant for obtaining the magenta toner, C.I. I. Dyes such as Solvent Red 1, 49, 52, 58, 63, 111 and 122; C.I. I. Pigment Red 5, pigments 48:1, 53:1, 57:1, 122, 139, 144, 149, 166, 177, 178, 222 and the like.

As the colorant for obtaining the cyan toner, C.I. I. Solvent Blue 25, Dye 36, Dye 60, Dye 70, Dye 93, Dye 95, etc.; C.I. I. Pigment Blue 1, the same 7, the same 15, the same 60, the same 62, the same 66, the same 76 and the like.

The colorant for obtaining the toner of each color can be used alone or in combination of two or more for each color.

The content of the colorant in the toner is preferably 0.5 to 20% by mass, more preferably 2 to 10% by mass.

<Release agent>
The toner according to the present invention may contain a release agent. The release agent used is not particularly limited, and various known waxes can be used. Examples of the wax include low-molecular-weight polypropylene, polyethylene, or oxidized low-molecular-weight polypropylene, polyolefin such as polyethylene, paraffin, and synthetic ester wax. Particularly, a synthetic ester wax is used because of its low melting point and low viscosity. It is preferable to use behenyl behenate, glycerin tribehenate, pentaerythritol tetrabehenate and the like as the synthetic ester wax.

The content of the release agent in the toner is preferably in the range of 1 to 30% by mass, more preferably 3 to 15% by mass.

<Charge control agent>
The toner according to the present invention may contain a charge control agent. The charge control agent used is not particularly limited as long as it is a substance capable of imparting positive or negative charge by triboelectric charging and is colorless, and various known positive charge control agents and negative charge control agents can be used. An electrostatic charge control agent can be used.

The content ratio of the charge control agent in the toner is preferably 0.01 to 30% by mass, more preferably 0.1 to 10% by mass.

<External additive>
In order to improve the fluidity, chargeability, cleaning property, etc. of the toner, the toner of the present invention is constituted by adding external additives such as a so-called post-treatment agent, a fluidizing agent and a cleaning aid to the toner particles. You may.

As the external additive, for example, silica particles, alumina particles, inorganic oxide particles such as titanium oxide particles, aluminum stearate particles, inorganic stearic acid compound particles such as zinc stearate particles, strontium titanate particles, zinc titanate particles. Inorganic particles such as inorganic titanate compound particles. These can be used alone or in combination of two or more.

These inorganic particles may be surface-treated with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, or the like in order to improve heat-resistant storage property and environmental stability.

The addition amount of these external additives is preferably 0.05 to 5% by mass in the toner, and more preferably 0.1 to 3% by mass.

<Average particle size of toner>
The average particle diameter of the toner is preferably 4 to 10 μm and more preferably 6 to 9 μm in terms of volume-based median diameter (D50). When the volume-based median diameter (D50) is within the above range, the transfer efficiency is increased, the halftone image quality is improved, and the image quality of fine lines and dots is improved.

In the present invention, the volume-based median diameter (D50) of the toner is a computer system (Beckman Coulter) in which "Coulter Counter 3" (manufactured by Beckman Coulter, Inc.) is equipped with data processing software "Software V3.51". It is measured and calculated using a measuring device connected to a product manufactured by Co., Ltd.

Specifically, 0.02 g of a measurement sample (toner) was used as a surfactant solution 20 mL (for the purpose of dispersing toner particles, for example, a neutral detergent containing a surfactant component was diluted 10 times with pure water. (Solution) and acclimated to it, ultrasonic dispersion is carried out for 1 minute to prepare a toner dispersion, and this toner dispersion is put in "ISOTONII" (manufactured by Beckman Coulter, Inc.) in a sample stand. Pipette into the beaker until the indicated concentration on the measuring device is 8%.

Here, by setting this concentration range, reproducible measurement values can be obtained. Then, in the measuring device, the number of particles to be measured was set to 25,000, the aperture diameter was set to 50 μm, and the frequency value was calculated by dividing the range of 1 to 30 μm, which is the measurement range, into 256. The particle diameter of% is the volume-based median diameter (D50).

[Toner manufacturing method]
The method for producing the toner of the present invention is not particularly limited. For example, in the case of using an azobenzene derivative alone as a toner, the azobenzene derivative obtained by the above synthesis method is crushed using a device such as a hammer mill, a feather mill, a counter jet mill, and then spin air sieve, classeal, A production method including classifying to a desired particle size using a dry classifier such as Micron Classifier is preferable.

When manufacturing a toner containing an azobenzene derivative and a colorant but no binder resin, a solvent in which both the azobenzene derivative and the colorant are dissolved is used to dissolve the azobenzene derivative and the colorant into a solution, and then the solvent is removed. Then, a manufacturing method including crushing and classifying by the same method as described above is preferable.

In the case of producing a toner containing an azobenzene derivative, a colorant, and a binder resin, it is preferable to use a production method utilizing an emulsion aggregation method in which the particle size and shape can be easily controlled.

Such a manufacturing method is
(1A) Binder resin particle dispersion liquid preparing step for preparing a binder resin particle dispersion liquid (1B) Colorant particle dispersion liquid preparing step for preparing a colorant particle dispersion liquid (1C) Azobenzene derivative particle dispersion liquid Azobenzene derivative particle dispersion liquid preparation step to be prepared (2) A flocculant is added to the aqueous medium in which the binder resin particles, the colorant particles and the azobenzene derivative particles are present, and salting out proceeds and at the same time flocculation/melting (3) Maturation step of forming toner particles by controlling the shape of the associated particles (4) Filtering the toner particles from the aqueous medium, and removing the toner particles from the surfactant. And a step of removing (5) a drying step of drying the washed toner particles, and a step of adding an external additive to the dried toner particles. preferable. Hereinafter, the steps (1A) to (1C) will be described.

(1A) Binder Resin Particle Dispersion Liquid Preparation Step In this step, resin particles are formed by conventionally known emulsion polymerization and the resin particles are aggregated and fused to form binder resin particles. As an example, a polymerizable monomer that constitutes the binder resin is added to an aqueous medium and dispersed, and the polymerizable monomer is polymerized with a polymerization initiator to prepare a dispersion liquid of the binder resin particles. ..

Further, as a method of obtaining a binder resin particle dispersion, other than the method of polymerizing a polymerizable monomer with a polymerization initiator in the above aqueous medium, for example, a dispersion treatment in an aqueous medium without using a solvent. Or a method in which the crystalline resin is dissolved in a solvent such as ethyl acetate to obtain a solution, and the solution is emulsified and dispersed in an aqueous medium using a disperser, and then the solvent is removed.

At this time, if necessary, the binder resin may contain a release agent in advance. Further, for the purpose of dispersion, polymerization is appropriately performed in the presence of a known surfactant (eg, anionic surfactant such as polyoxyethylene (2) sodium dodecyl ether sulfate, sodium dodecyl sulfate, and dodecylbenzenesulfonic acid). Is also preferable.

The volume-based median diameter of the binder resin particles in the dispersion is preferably 50 to 300 nm. The volume-based median diameter of the binder resin particles in the dispersion can be measured by a dynamic light scattering method using "Microtrac UPA-150" (manufactured by Nikkiso Co., Ltd.).

(1B) Colorant Particle Dispersion Liquid Preparation Step This colorant particle dispersion liquid preparation step is a step of dispersing the colorant into fine particles in an aqueous medium to prepare a colorant particle dispersion liquid.

Dispersion of the colorant can be performed by utilizing mechanical energy. The number-based median diameter of the colorant particles in the dispersion is preferably 10 to 300 nm, and more preferably 50 to 200 nm. The number-based median diameter of the colorant particles can be measured using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).

(1C) Azobenzene derivative particle dispersion liquid preparation step This azobenzene derivative particle dispersion liquid preparation step is a step of dispersing the azobenzene derivative in the form of fine particles in an aqueous medium to prepare a dispersion liquid of azobenzene dispersion particles. In preparing the azobenzene derivative particle dispersion liquid, first, an azobenzene derivative emulsion is prepared. Examples of the method for preparing the azobenzene derivative emulsion include a method of obtaining an azobenzene derivative solution in which an azobenzene derivative is dissolved in an organic solvent and then emulsifying the azobenzene derivative solution in an aqueous medium.

The method of dissolving the azobenzene derivative in the organic solvent is not particularly limited, and for example, there is a method of adding the azobenzene derivative to the organic solvent and stirring and mixing so that the azobenzene derivative is dissolved. The addition ratio of the azobenzene derivative is preferably 5 parts by mass or more and 100 parts by mass or less, more preferably 10 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the organic solvent.

Next, the azobenzene derivative liquid and the aqueous medium are mixed and stirred using a known disperser such as a homogenizer. As a result, the azobenzene derivative becomes droplets and is emulsified in the aqueous medium to prepare an azobenzene derivative emulsion.

The addition ratio of the azobenzene derivative liquid is preferably 10 parts by mass or more and 90 parts by mass or less, more preferably 30 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the aqueous medium.

Further, the temperature of each of the azobenzene derivative liquid and the aqueous medium at the time of mixing the azobenzene derivative liquid and the aqueous medium is in a temperature range below the boiling point of the organic solvent, preferably 20° C. or higher and 80° C. or lower, and more preferably Is 30° C. or higher and 75° C. or lower. When the azobenzene derivative liquid and the aqueous medium are mixed, the temperature of the azobenzene derivative liquid and the temperature of the aqueous medium may be the same or different, and preferably the same.

As for the stirring conditions of the disperser, for example, when the capacity is 1 to 3 L, the number of revolutions thereof is preferably 7,000 rpm or more and 20,000 rpm or less, and the stirring time is preferably 10 minutes or more and 30 minutes or less.

The azobenzene derivative particle dispersion liquid is prepared by removing the organic solvent from the azobenzene derivative emulsion. Examples of the method of removing the organic solvent from the azobenzene derivative emulsion include known methods such as blowing air, heating, reducing pressure, or a combination thereof.

As an example, the azobenzene derivative emulsion is, for example, in an atmosphere of an inert gas such as nitrogen, preferably 25° C. or higher and 90° C. or lower, more preferably 30° C. or higher and 80° C. or lower, and 80% by mass of the initial amount of the organic solvent. The organic solvent is removed by heating until about 95% by mass or less is removed. As a result, the organic solvent is removed from the aqueous medium, and the azobenzene derivative particle dispersion liquid in which the azobenzene derivative particles are dispersed in the aqueous medium is prepared.

The mass average particle diameter of the azobenzene derivative particles in the azobenzene derivative particle dispersion is preferably 90 nm or more and 1200 nm or less. The mass average particle diameter of the azobenzene derivative particles is appropriately adjusted by adjusting the viscosity when the azobenzene derivative is mixed with an organic solvent, the mixing ratio of the azobenzene derivative liquid and water, and the stirring speed of the disperser when preparing the azobenzene derivative emulsion. By doing so, it can be set within the above range. The mass average particle diameter of the azobenzene derivative particles in the azobenzene derivative particle dispersion liquid can be measured using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).

<Organic solvent>
The organic solvent used in this step can be used without particular limitation as long as it can dissolve the azobenzene derivative of the present invention. Specifically, esters such as ethyl acetate and butyl acetate, ethers such as diethyl ether, diisopropyl ether, and tetrahydrofuran, ketones such as acetone and methyl ethyl ketone, saturated hydrocarbons such as hexane and heptane, dichloromethane, dichloroethane, and tetraethyl ether. Examples thereof include halogenated hydrocarbons such as carbon chloride.

Such organic solvents may be used alone or in combination of two or more. Among these organic solvents, ketones and halogenated hydrocarbons are preferable, and methyl ethyl ketone and dichloromethane are more preferable.

<Aqueous medium>
Examples of the aqueous medium used in this step include water, or an aqueous medium containing water as a main component, a water-soluble solvent such as alcohols and glycols, and an optional component such as a surfactant and a dispersant. To be As the aqueous medium, a mixture of water and a surfactant is preferably used.

Examples of the surfactant include cationic surfactants, anionic surfactants, nonionic surfactants and the like. Examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, hexadecyl trimethyl ammonium bromide and the like. Examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecylbenzenesulfonate, sodium dodecyl sulfate. Examples of nonionic surfactants include polyoxyethylene dodecyl ether, polyoxyethylene hexadecyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene sorbitan monooleate ether, and monodecanoyl. Examples include sucrose.

Such surfactants can be used alone or in combination of two or more. Among the surfactants, preferably anionic surfactants, more preferably sodium dodecylbenzene sulfonate are used.

The addition amount of the surfactant is preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.04 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the aqueous medium.

The steps from (2) association step to (6) external additive addition step can be carried out according to various conventionally known methods.

The aggregating agent used in the association step (2) is not particularly limited, but one selected from metal salts is preferably used. Examples of the metal salt include monovalent metal salts such as salts of alkali metals such as sodium, potassium and lithium; divalent metal salts such as calcium, magnesium, manganese and copper; trivalent metal salts such as iron and aluminum. And so on. Specific examples of the metal salt 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 because it can proceed. These can be used alone or in combination of two or more.

[Developer]
The toner of the present invention may be used, for example, as a one-component magnetic toner containing a magnetic substance, as a two-component developer mixed with a so-called carrier, or as a non-magnetic toner alone. Any of them can be preferably used.

As the magnetic material, for example, magnetite, γ-hematite, or various ferrites can be used.

As the carrier constituting the two-component developer, magnetic particles made of conventionally known materials such as iron, steel, nickel, cobalt, ferrite, metals such as magnetite, alloys of those metals with metals such as lead and lead are used. Can be used.

As the carrier, it is preferable to use a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, or a so-called resin dispersion type carrier in which magnetic powder is dispersed in a binder resin. The coating resin is not particularly limited, but for example, an olefin resin, a styrene resin, a styrene acrylic resin, a silicone resin, a polyester resin, a fluororesin or the like is used. The resin for forming the resin-dispersed carrier is not particularly limited, and known ones can be used. For example, acrylic resin, styrene acrylic resin, polyester resin, fluororesin, phenol resin, etc. can be used. You can

The volume-based median diameter of the carrier is preferably 20 to 100 μm, and more preferably 25 to 80 μm. The volume-based median diameter of the carrier can be typically measured by a laser diffraction particle size distribution analyzer “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

The mixing amount of the toner with respect to the carrier is preferably 2 to 10% by mass with the total mass of the toner and the carrier being 100% by mass.

[Image forming method]
The toner of the present invention can be used in various known electrophotographic image forming methods. For example, it can be used for a monochrome image forming method or a full-color image forming method. The full-color image forming method includes a four-cycle image forming method including four types of color developing devices for yellow, magenta, cyan, and black, and one photoconductor, and color developing for each color. The present invention can be applied to any image forming method such as a tandem type image forming method in which an image forming unit having a device and a photoconductor is mounted for each color.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus 100 used in an image forming method according to an embodiment of the present invention. However, the image forming apparatus used in the present invention is not limited to the following modes and illustrated examples. FIG. 1 shows an example of a monochrome image forming apparatus 100, but the present invention can also be applied to a color image forming apparatus.

The image forming apparatus 100 is an apparatus that forms an image on a recording sheet S as a recording medium, and includes an image reading device 71 and an automatic document feeder 72, and an image is formed on the recording sheet S conveyed by a sheet conveying system 7. Image formation is performed by the forming unit 10, the first irradiation unit 40a, the pressure bonding unit 9, and the second irradiation unit 40b. Hereinafter, the first irradiation unit 40a and the second irradiation unit 40b are collectively referred to as the irradiation unit 40.

Although the recording sheet S is used as the recording medium in the image forming apparatus 100, the medium to be subjected to image formation may be other than the sheet.

The document d placed on the document table of the automatic document feeding device 72 is scanned and exposed by the optical system of the scanning exposure device of the image reading device 71 and read into the image sensor CCD. The analog signal photoelectrically converted by the image sensor CCD is subjected to analog processing, A/D conversion, shading correction, image compression processing, etc. in the image processing unit 20, and then input to the exposure unit 3 of the image forming unit 10. It

The paper transport system 7 includes a plurality of trays 16, a plurality of paper feed units 11, a transport roller 12, a transport belt 13, and the like. Each of the trays 16 stores a recording sheet S of a predetermined size, and operates the sheet feeding unit 11 of the tray 16 that is determined according to an instruction from the control unit 90 to supply the recording sheet S. The transport roller 12 transports the recording paper S sent from the tray 16 by the paper feeding unit 11 or the recording paper S carried in from the manual paper feeding unit 15 to the image forming unit 10.

In the image forming unit 10, the charger 2, the exposure unit 3, the developing unit 4, the transfer unit 5, the charge removing unit 6, and the cleaning unit 8 are arranged in this order around the photoconductor 1 along the rotation direction of the photoconductor 1. It is arranged and configured.

The photoconductor 1, which is an image carrier, is an image carrier having a photoconductive layer formed on its surface, and is configured to be rotatable in the direction of the arrow in FIG. 1 by a driving device (not shown). A thermo-hygrometer 17 that detects the temperature and humidity inside the image forming apparatus 100 is provided near the photoconductor 1.

The charger 2 evenly charges the surface of the photoconductor 1 to uniformly charge the surface of the photoconductor 1. The exposure device 3 is provided with a beam emission source such as a laser diode, and the surface of the charged photoconductor 1 is irradiated with the beam light so that the electric charge in the irradiated portion is erased and the photoconductor 1 is exposed to light in accordance with image data. Form a latent image. The developing unit 4 supplies the toner accommodated therein to the photoconductor 1 to form a toner image based on the electrostatic latent image on the surface of the photoconductor 1.

The transfer unit 5 faces the photoconductor 1 via the recording sheet S and transfers the toner image onto the recording sheet S. The charge removing unit 6 removes charge on the photoconductor 1 after the toner image is transferred. The cleaning unit 8 includes a blade 85. The blade 85 cleans the surface of the photoreceptor 1 to remove the developer remaining on the surface of the photoreceptor 1.

The recording sheet S to which the toner image is transferred is conveyed to the pressure-bonding section 9 by the conveyor belt 13. The pressure-bonding section 9 is arbitrarily installed, and the recording paper S on which the toner image is transferred is subjected to a fixing process by applying only pressure or heat and pressure by the pressure members 91 and 92, thereby recording. The image is fixed on the paper S. The recording sheet S on which the image has been fixed is conveyed by the conveying rollers to the sheet discharge unit 14, and discharged from the sheet discharge unit 14 to the outside of the machine.

Further, the image forming apparatus 100 is provided with a sheet reversing unit 24, and the recording sheet S that has been subjected to the heat fixing process is conveyed to the sheet reversing unit 24 before the sheet ejecting unit 14, and the front and back sides are reversed and ejected. Alternatively, it is possible to carry the image on both sides of the recording sheet S again by conveying the recording sheet S with the front and back reversed to the image forming unit 10.

<Irradiator>
FIG. 2 is a schematic configuration diagram of the irradiation unit 40 in the image forming apparatus 100.

The image forming apparatus 100 according to the embodiment of the present invention includes an irradiation unit 40 including a first irradiation unit 40a and a second irradiation unit 40b. A light emitting diode (LED), a laser light source, etc. are mentioned as an example of the device which comprises the irradiation part 40.

The first irradiation section 40a melts a compound (azobenzene derivative of the present invention) contained in the developer and undergoes a phase transition by light absorption, and is preferably in the range of 300 nm or more and less than 400 nm, more preferably 330 nm or more and 390 nm. Irradiate with ultraviolet light having a wavelength in the range below. Dose of ultraviolet light in the first illumination portion 40a is preferably in the range of 0.1~200J / cm ^2, more preferably in the range of 0.5~100J / cm ^2, more preferably, 1.0 It is within the range of 50 J/cm ² .

The second irradiation unit 40b is for solidifying the azobenzene derivative, and irradiates visible light having a wavelength in the range of preferably 400 nm to 800 nm, more preferably 450 nm to 650 nm. The irradiation amount of visible light in the second irradiation section 40b is preferably 0.1 to 200 J/cm ² , more preferably 0.5 to 100 J/cm ² , and still more preferably 1.0 to 50 J/cm ² . ..

That is, the image forming method according to one embodiment of the present invention includes the step of forming a toner image of the toner of the present invention on a recording medium, and irradiating the toner image with light having a wavelength of 300 nm or more and less than 400 nm. And then softening the toner image, and irradiating the softened toner image with light having a wavelength of 400 nm or more and 800 nm or less to solidify the toner image and fix it on a recording medium.

The first irradiating section 40a and the second irradiating section 40b irradiate light toward the first surface of the recording sheet S holding the toner image on the side of the photoconductor, and are nipped between the photoconductor 1 and the transfer roller 50. It is arranged on the photoconductor side with respect to the surface of the recording sheet S. The first irradiation unit 40a and the second irradiation unit 40b are arranged in this order along the conveyance direction of the recording paper S (paper conveyance direction).

The first irradiation unit 40 a is arranged downstream of the nip position between the photoconductor 1 and the transfer roller 40 in the paper transport direction and upstream of the pressure bonding unit 9 in the paper transport direction.

The second irradiation section 40b is installed downstream of the first irradiation section 40a in the sheet conveyance direction and upstream of the sheet discharge section 14 in the sheet conveyance direction. The second irradiation unit 40b can be installed between the pressure bonding unit 9 and the paper discharge unit 14 in the paper conveyance direction.

According to the image forming method according to the embodiment of the present invention, after the charging device 2 applies a uniform potential to the photoconductor 1 to charge the photoconductor 1, the photoconductor 1 is exposed by the light flux irradiated by the exposure device 3 based on the original image data. The body 1 is scanned to form an electrostatic latent image. Next, the developing section 4 supplies a developer containing a compound that undergoes a phase transition by light absorption onto the photoreceptor 1.

When the recording sheet S is conveyed from the tray 16 to the image forming unit 10 at the timing when the toner image carried on the surface of the photoconductor 1 reaches the position of the transfer member 50 by the rotation of the photoconductor 1, the recording member S is transferred to the transfer member 50. By the applied transfer bias, the toner image on the photoconductor 1 is transferred onto the recording sheet S nipped between the transfer member 50 and the photoconductor 1.

Further, the transfer member 50 also functions as a pressing member, so that the azobenzene derivative contained in the toner image can be surely brought into close contact with the recording paper S while the toner image can be transferred from the photoconductor 1 to the recording paper S. You can

After the toner image is transferred to the recording sheet S, the blade 85 of the cleaning unit 8 removes the developer remaining on the surface of the photoconductor 1.

In the process in which the recording sheet S on which the toner image has been transferred is conveyed to the pressure-bonding section 9 by the conveying belt 13, the first irradiation section 40a detects the toner image transferred onto the recording sheet S from 300 nm to less than 400 nm. Irradiate ultraviolet light having a wavelength. By irradiating the toner image on the first surface of the recording sheet S with the ultraviolet light by the first irradiation unit 40a, the toner image can be more surely melted, and the fixing property of the toner image on the recording sheet S can be improved. Can be improved.

When the recording sheet S holding the toner image reaches the pressure contact portion 9 by the conveyor belt 13, the pressing members 91 and 92 press the toner image onto the first surface of the recording sheet S. Before the fixing process is performed by the pressure-bonding unit 9, the toner image is softened by the irradiation of the ultraviolet light from the first irradiation unit 40a, so that energy saving of the image pressure-bonding on the recording sheet S can be achieved. That is, in the image forming method of the present invention, the softened toner image is applied by the pressing member before the step of irradiating visible light having a wavelength of 400 nm or more and 800 nm or less to solidify the toner image and fix the toner image on the recording medium. It is preferable to further include the step of pressing.

Further, the pressing member 91 can heat the toner image on the recording sheet S when the recording sheet S passes between the pressing members 91 and 92. The toner image softened by the light irradiation is further softened by this heating, and as a result, the fixing property of the toner image on the recording sheet S is further improved. The temperature of the pressure member 91 when heated is preferably 30° C. or higher and 100° C. or lower, and more preferably 40° C. or higher and 100° C. or lower.

The recording paper S passing between the pressure members 91 and 92 irradiates the toner image on the recording paper S with visible light having a wavelength of 400 nm or more and 800 nm or less before reaching the paper discharge unit 14. The second irradiation unit 40b is provided. By irradiating the visible light from the second irradiator 40b, the toner image on the recording sheet S can be solidified more reliably, and the fixing property of the toner image on the recording sheet S can be further improved.

When images are to be formed on both sides of the recording paper S, the recording paper S that has been subjected to the pressure-bonding process is conveyed to the paper reversing unit 24 in front of the paper discharge unit 14 and is reversed and discharged, or the front and back are reversed. The recording sheet S is conveyed again to the image forming unit 10.

The effects of the present invention will be described using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples.

[Synthesis of azobenzene derivative]
<Synthesis of Compound in which R in Chemical Formula (1) is an Alkyl Group>
Toluene 10 mL and active manganese dioxide (0.30 g, 3.5 mmol) were added to 4-hexylaniline (0.17 g, 1.0 mmol), and stirring was continued at 120° C. for 8 hours. After evaporating the solvent under reduced pressure, the mixture was extracted with ethyl acetate, the organic layer was washed with saturated brine, and dried over anhydrous magnesium sulfate. After filtering this, the solvent was distilled off under reduced pressure, and the obtained solid was purified by silica gel column chromatography using a mixed solution of ethyl acetate:hexane=1:5 as a developing solvent. Then, the solvent was removed to obtain 4,4′-dihexylazobenzene (azobenzene derivative 1, a compound in which R in the chemical formula (1) is an n-hexyl group).

Further, instead of 4-hexylaniline, in the same manner as above, except that 4-ethylaniline, 4-butylaniline, 4-octylaniline, 4-dodecylaniline, and 4-hexadecylaniline are respectively changed. Azobenzene derivatives 2 to 6 were synthesized.

<Synthesis of Compound in which R in Chemical Formula (1) is an Alkoxy Group>
DMF (10 mL), 1-bromohexane (0.99 g, 6.0 mmol), and potassium carbonate (0.69 g, 5.0 mmol) were added to 4,4′-dihydroxyazobenzene (0.21 g, 1.0 mmol), and the mixture was heated at 80° C. After stirring for 2 hours at room temperature, stirring was continued for 12 hours at room temperature. After evaporating the solvent under reduced pressure, the mixture was extracted with ethyl acetate, the organic layer was washed with saturated brine, and dried over anhydrous magnesium sulfate. After filtering this, the solvent was distilled off under reduced pressure, and the obtained solid was purified by silica gel column chromatography using a mixed solution of ethyl acetate:hexane=5:95 as a developing solvent. Then, the solvent was removed to obtain 4,4′-bis(hexyloxy)azobenzene (azobenzene derivative 7, a compound in which R in the chemical formula (1) is an n-hexyloxy group).

In addition, instead of 1-bromohexane, 1-bromoethane, 1-bromooctane, 1-bromododecane, and 1-bromohexadecane were respectively changed, and azobenzene derivatives 8 to 11 were synthesized in the same manner as above. did.

The structures and compound names of the synthesized azobenzene derivatives are shown in Table 1 below.

[Preparation of toner]
<Preparation of Toners 1-8 and 14-16>
The azobenzene derivative 1 was roughly pulverized with a hammer mill so that the particle size was 1 mm or less, and then finely pulverized using a collision type air flow pulverizer using high pressure gas to obtain a pulverized azobenzene derivative. Next, a fine powder and a coarse powder were classified and removed at the same time by using a classeal to obtain a toner 1. The volume-based median diameter of Toner 1 was 8.2 μm.

Further, the azobenzene derivative 2 and the azobenzene derivatives 4 to 11 were pulverized in the same manner as above using a hammer mill and then classified with a classeal to obtain toners 2 to 8 and 14 to 15. The volume-based median diameters of Toners 2 to 8 and Toners 14 to 15 are as shown in Table 2 below.

Since the azobenzene derivative 3 was liquid at room temperature, powder as a toner could not be obtained.

<Preparation of Toner 9>
(Preparation of styrene acrylic resin particle dispersion)
201 parts by mass of styrene, 117 parts by mass of n-butyl acrylate, and 18.3 parts by mass of methacrylic acid were mixed, and this monomer mixture solution was heated to 80° C. with stirring, and 172 parts by mass of behenyl behenate were gradually added. And dissolved.

Next, an aqueous surfactant solution obtained by dissolving 3 parts by mass of dodecylbenzenesulfonic acid, which is an anionic surfactant, in 1182 parts by mass of pure water is heated to 80° C., the above-mentioned monomer mixture liquid is added, and high speed stirring is performed. Then, a monomer dispersion liquid was prepared.

867.5 parts by mass of pure water was put into a polymerization device equipped with a stirrer, a cooling pipe, a temperature sensor, and a nitrogen introducing pipe, and the internal temperature was adjusted to 80° C. while stirring under a nitrogen stream. The above monomer dispersion was charged into this polymerization apparatus, and further an aqueous polymerization initiator solution prepared by dissolving 8.55 parts by mass of potassium persulfate in 162.5 parts by mass of pure water was charged.

After adding the polymerization initiator aqueous solution, 5.2 parts by mass of n-octyl mercaptan was added over 35 minutes, and polymerization was further performed at 80° C. for 2 hours. Next, an aqueous solution of a polymerization initiator in which 9.96 parts by mass of potassium persulfate was dissolved in 189.3 parts by mass of pure water was added, and 366.1 parts by mass of styrene, 179.1 parts by mass of n-butyl acrylate, and n-. A monomer solution prepared by mixing 7.2 parts by mass of octyl mercaptan was added dropwise over 1 hour. After the monomer solution was dropped, the polymerization treatment was continued for 2 hours and then cooled to room temperature (25° C.) to prepare a dispersion liquid containing styrene acrylic resin particles which are binder resin particles.

(Preparation of carbon black dispersion)
11.5 parts by mass of sodium n-dodecyl sulfate is dissolved in 1600 parts by mass of pure water, 25 parts by mass of carbon black "Mogal L (manufactured by Cabot Corporation)" is gradually added, and then "Clearmix (registered trademark) W" is added. A carbon black dispersion was prepared using "Motion CLM-0.8 (manufactured by M Technique Co., Ltd.)". The particle diameter of carbon black in the dispersion was 160 nm in terms of median diameter on a number basis.

(Preparation of azobenzene derivative particle dispersion)
80 parts by mass of dichloromethane and 20 parts by mass of azobenzene derivative 1 were mixed and stirred while heating at 50° C. to obtain a liquid containing azobenzene derivative 1. To 100 parts by mass of this solution, a mixed solution of 99.5 parts by mass of distilled water heated to 50° C. and 0.5 part by mass of a 20% by mass sodium dodecylbenzenesulfonate aqueous solution was added. Then, the mixture was stirred at 16000 rpm for 20 minutes with a homogenizer equipped with a shaft generator 18F to emulsify to obtain an azobenzene derivative emulsion.

The obtained azobenzene derivative emulsion was charged into a separable flask and heated and stirred at 40° C. for 90 minutes while feeding nitrogen into the gas phase to remove the organic solvent to obtain an azobenzene derivative particle dispersion liquid. The solid content concentration of the azobenzene derivative particle dispersion was 11.0% by mass. The particle size of the azobenzene derivative particles in the azobenzene derivative particle dispersion was measured with an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.), and the mass average particle size was 265 nm. ..

(Agglomeration/fusion)
The styrene-acrylic resin particle dispersion liquid produced above was 360 parts by mass in terms of solid content, the azobenzene derivative particle dispersion liquid was 360 parts in terms of solid content, ion-exchanged water was 900 parts by mass, and the carbon black dispersion was in solid content. 70 parts by mass was put into a reactor equipped with a stirrer, a temperature sensor, and a cooling pipe. The temperature in the container was maintained at 30° C., and a 5 mol/liter sodium hydroxide aqueous solution was added to adjust the pH to 10.

Next, an aqueous solution prepared by dissolving 2 parts by mass of magnesium chloride hexahydrate in 1000 parts by mass of ion-exchanged water was added dropwise with stirring over 10 minutes, and then temperature rising was started, and the system was heated over 80 minutes over 80 minutes. The temperature was raised to 0°C and the particle growth reaction was continued while maintaining the temperature at 80°C. In this state, the particle size of the associated particles was measured with "Multisizer 3" (manufactured by Beckman Coulter, Inc.), and when the volume-based median diameter (D50) was 6.5 μm, 190 parts by mass of sodium chloride Was added to an aqueous solution of 760 parts by mass of ion-exchanged water to stop grain growth. After stirring at 80° C. for 1 hour, the temperature was further raised, and the particles were heated and stirred at 85° C. to promote fusion of particles. Then, by cooling to 30° C., a dispersion liquid of toner particles was obtained.

The dispersion liquid of toner particles obtained above was subjected to solid-liquid separation with a centrifuge to form a wet cake of toner particles. The wet cake was washed with ion-exchanged water at 35° C. in the centrifuge until the electric conductivity of the filtrate became 5 μS/cm, and then transferred to a “flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.)” to obtain a water content To 0.5% by mass to obtain toner 9.

The volume-based median diameter (D50) of the obtained toner 9 was measured using "Coulter Counter 3 (manufactured by Beckman Coulter, Inc.)", and it was 7.2 µm.

<Preparation of Toners 10-11>
Toners 10 to 11 were produced in the same manner as in <Preparation of Toner 9> above, except that the mass ratio of the azobenzene derivative 1 to the binder resin was changed as shown in Table 2 below.

The volume-based median diameter (D50) of the obtained toner 10 was measured using "Coulter Counter 3 (manufactured by Beckman Coulter, Inc.)", and it was 6.8 μm. Further, the volume-based median diameter (D50) of Toner 11 was measured by the same method as described above, and was 7.5 μm.

<Preparation of Toner 12>
Instead of the styrene acrylic resin particle dispersion, the polyester resin particle dispersion prepared as described below was used, and the azobenzene derivative 7 was used in place of the azobenzene derivative 1 in the preparation of the above azobenzene derivative particle dispersion. Toner 12 was prepared in the same manner as in <Preparation of Toner 9>, except that the step of (fusing) was performed as follows.

(Preparation of polyester resin particle dispersion)
500 parts by mass of bisphenol A propylene oxide 2 mol adduct, 117 parts by mass terephthalic acid, 81 parts by mass fumaric acid were placed in a four-necked flask having a capacity of 10 liters equipped with a nitrogen introduction tube, a dehydration tube, a stirrer, and a thermocouple. Then, 2 parts by mass of tin octylate (esterification catalyst) was added, and a polycondensation reaction was carried out at a temperature of 230° C. for 8 hours. Furthermore, after continuing the polycondensation reaction at 8 kPa for 1 hour, it was cooled to 160° C. to obtain a polyester resin. 100 parts by mass of polyester resin was crushed with "Landel mill type: RM" (manufactured by Tokuju Seisakusho Co., Ltd.), mixed with 638 parts by mass of 0.26% by mass aqueous sodium lauryl sulfate solution prepared in advance, and ultrasonic waves while stirring. Using a homogenizer "US-150T" (manufactured by Nippon Seiki Seisakusho Co., Ltd.), ultrasonic dispersion was performed at V-LEVEL at 300 µA for 30 minutes to prepare a polyester resin particle dispersion liquid.

(Agglomeration/fusion)
The polyester resin particle dispersion prepared above was 540 parts by mass in terms of solid content, the azobenzene derivative particle dispersion was 180 parts by mass in terms of solid content, 900 parts by mass of ion-exchanged water, and the carbon black dispersion was 70 in terms of solid content. The mass part was put into a reactor equipped with a stirrer, a temperature sensor, and a cooling pipe. The temperature in the container was maintained at 30° C., and a 5 mol/liter sodium hydroxide aqueous solution was added to adjust the pH to 10.

Next, an aqueous solution prepared by dissolving 2 parts by mass of magnesium chloride hexahydrate in 1000 parts by mass of ion-exchanged water was added dropwise with stirring over 10 minutes, and then the temperature was started, and the system was heated over 75 minutes for 75 minutes. The temperature was raised to 0°C and the particle growth reaction was continued while maintaining the temperature at 75°C. In this state, the particle size of the associated particles was measured with "Multisizer 3" (manufactured by Beckman Coulter, Inc.), and when the volume-based median diameter (D50) was 6.5 μm, 190 parts by mass of sodium chloride Was added to an aqueous solution of 760 parts by mass of ion-exchanged water to stop grain growth. After stirring at 75° C. for 1 hour, the temperature was further raised, and heating and stirring were performed at 80° C. to promote fusion of particles. Then, by cooling to 30° C., a dispersion liquid of toner particles was obtained.

The toner particle dispersion liquid produced in the above aggregation/fusion step was subjected to solid-liquid separation with a centrifuge to form a wet cake of toner particles. The wet cake was washed with ion-exchanged water at 35° C. in the centrifuge until the electric conductivity of the filtrate became 5 μS/cm, and then transferred to a “flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.)” to obtain a water content To 0.5% by mass to obtain a toner 12.

The volume-based median diameter (D50) of the obtained toner 12 was measured using "Coulter Counter 3 (manufactured by Beckman Coulter, Inc.)" and found to be 7.0 µm.

<Production of Toner 13>
Toner 13 was prepared in the same manner as in <Preparation of Toner 12> except that the mass ratio of the azobenzene derivative 7 to the binder resin was changed as shown in Table 2 below.

The volume-based median diameter (D50) of the obtained toner 13 was measured using "Coulter Counter 3 (manufactured by Beckman Coulter, Inc.)" and was 6.5 μm.

<Preparation of Toners 17-18>
Instead of the azobenzene derivative 1, a suspension of Compound 1 or a suspension of Compound 2 prepared by the following method was used, and the mass ratio of Compound 1 or Compound 2 to the binder resin was as shown in Table 2 below. Toners 17 to 18 were prepared in the same manner as in <Preparation of Toner 9> except that the above was changed.

The volume-based median diameter (D50) of the obtained toner 17 was measured using "Coulter Counter 3 (manufactured by Beckman Coulter, Inc.)" and was found to be 7.2 μm. The volume-based median diameter (D50) of Toner 18 was 7.0 μm as measured by the same method as described above.

(Preparation of suspension of compound 1)
It is represented by the following chemical formula (2) in the same manner as in “(1-1) Preparation of UV softening material suspension A” described in paragraphs “0217” to “0227” of JP-A-2014-191078. A suspension of compound 1 was prepared.

(Preparation of suspension of compound 2)
It is represented by the following chemical formula (3) in the same manner as in “(1-2) Preparation of UV softening material suspension B” described in paragraphs “0227” to “0238” of JP-A-2014-191078. A suspension of compound 2 was prepared.

[Development of developer]
9.5 g of iron powder having a volume-based median diameter of 70 μm and 0.5 g of toner of each of the examples and comparative examples were placed in a 20 ml glass container, 200 times per minute, a swing angle of 45 degrees, and an arm of 50 cm for 20 minutes. It was shaken for a minute to prepare a developer.

[Evaluation: Fixability test]
The fixing property test was performed using the developer obtained above under a normal temperature and normal humidity environment (temperature 20° C., humidity 50% RH). The developer is placed between a pair of parallel flat plate (aluminum) electrodes having a developer on one side and plain paper (basis weight: 64 g/m ² ) on the other side while sliding the magnetic force, and the gap between the electrodes is 0. 5 mm, DC bias and AC bias were used to develop a toner under the condition that the toner adhesion amount was 3 g/m ² , a toner layer was formed on the surface of the paper, and the printed matter fixed by each fixing device was used. The 1 cm square image of this printed material was rubbed with "JK wiper (registered trademark)" (manufactured by Nippon Paper Crecia Co., Ltd.) under a pressure of 10 kPa three times, and the image fixing rate was evaluated. A fixing rate of 80% or more is passed. The image fixing rate is the density of the printed image and the image after rubbing measured by a reflection densitometer "RD-918" (manufactured by Sakata Inx Engineering Co., Ltd.), and the reflection density of the solid image after rubbing. Is a value obtained by dividing the value by the reflection density of the solid image after printing and expressed as a percentage.

The fixing device used was the following three types of devices, which were constructed by appropriately modifying the device shown in FIG.
No. 1: There is no pressure-bonding section 9 in FIG. 2, the wavelength of the ultraviolet light emitted from the first irradiation section 40a is 365 nm (light source: LED light source with an emission wavelength of 365 nm±10 nm), and the irradiation amount is 10 J/cm ² . is there. The wavelength of visible light emitted from the second irradiation unit 40b is 505 nm (light source: LED light source having an emission wavelength of 505 nm±10 nm), and the irradiation amount is 20 J/cm ² .
No. 2: There is the crimp portion 9 in FIG. 2, and the temperature of the pressing member 91 is 20° C. The light sources and irradiation amounts of the first irradiation unit and the second irradiation unit are No. Same as 1;
No. 3: There is the crimp portion 9 in FIG. 2, and the temperature of the pressing member 91 is 80° C. The light sources and irradiation amounts of the first irradiation unit and the second irradiation unit are No. Same as 1.

Table 2 below shows the configuration of each toner, the type of fixing device, and the evaluation results.

As is clear from Table 2 above, the toners of Examples 1 to 18 exhibited high fixing properties. On the other hand, the toners of Comparative Examples 1 to 2 and 4 to 5 had low fixability, and the toner of Comparative Example 3 was a liquid at room temperature and therefore could not be evaluated. Since the ultraviolet light source and the ultraviolet irradiation conditions used in the fixing property test are constant throughout the examples and comparative examples, the toner of the example has a higher softening rate by light irradiation than the toner of the comparative example. It can be said that the fixability is improved.

Comparing the fixing devices, in the case of the toner containing the binder resin, the temperature of the pressing member 91 is high. No. 3 is better when the fixing device of No. 3 is used. The fixability was improved as compared with the case where the fixing device of No. 2 was used (comparison between Examples 9 to 13 and Examples 14 to 18).

1 photoconductor,
2 charger,
3 exposure unit,
4 development department,
5 transfer part,
6 static eliminator,
7 Paper transport system,
8 cleaning section,
9 Crimp part,
10 image forming unit,
11 paper feed section,
12 transport rollers,
13 conveyor belt,
14 Paper output section,
15 Manual feed section,
16 trays,
17 Thermo-hygrometer,
20 Image processing unit,
24 Paper reversing section,
40 irradiation part,
40a 1st irradiation part,
40b 2nd irradiation part,
50 transfer roller,
71 image reading device,
72 automatic document feeder,
85 blades,
90 control unit,
91, 92 pressure member,
100 image forming apparatus,
d manuscript,
S recording paper.

Claims (7)

Toner containing an azobenzene derivative represented by the following chemical formula (1):
In the above chemical formula (1), two Rs are completely the same substituents, and R is an alkyl group or an alkoxy group having 6 to 16 carbon atoms. The toner according to claim 1, further comprising a binder resin. The toner according to claim 2, wherein the binder resin includes at least one selected from the group consisting of styrene acrylic resin and polyester resin. The toner according to claim 1, further comprising a colorant. Forming a toner image made of the toner according to any one of claims 1 to 4 on a recording medium;
Irradiating the toner image with light having a wavelength of 300 nm or more and less than 400 nm to soften the toner image;
Irradiating the softened toner image with light having a wavelength of 400 nm or more and 800 nm or less to solidify the toner image and fix the toner image on a recording medium;
An image forming method including: The image forming method according to claim 5, further comprising a step of pressing the softened toner image with a pressing member before the step of fixing the toner image on the recording medium. The image forming method according to claim 6, wherein the temperature of the pressure member is 30° C. or higher and 100° C. or lower.