JP2001183871A - Electrophotographic toner, method for producing same, two-component developer and color image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic toner which imparts high image quality to a full-color image and is excellent in light resistance, transparency and powdery fluidity, a method for producing the toner, a two-component developer using the toner and a color image forming method using the toner. SOLUTION: The electrophotographic toner contains a UV absorber whose melting point is in the range of 90-150 deg.C besides a bonding resin and a colorant as principal components and has a light transmittance of >=65. The method for producing the toner has a kneading step in which the discharge temperature of a kneaded material is in the range from (the melting point of the UV absorber)-10 deg.C to (the melting point of the UV absorber) +30 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic toner used in electrophotography, electrostatic recording, electrostatic printing, and the like.
The present invention relates to a method for producing the toner, a two-component developer containing the toner for electrophotography, and a color image forming method using the toner for electrophotography.

[0002]

2. Description of the Related Art In an electrophotographic system in which a visible image is formed by developing an electric latent image with a developer, an electric latent image is formed on a photoreceptor, and then the latent image is developed with a developer. After the transfer of the toner image to the toner image or the like, the toner image is fixed by heat or pressure to obtain a visible image. In order to obtain a multicolor image of color, an original is exposed using a color separation filter, or an image read by a scanner is written and exposed by a laser, and the above-described process is performed using a yellow, magenta, and cyan color developer ( (Adding a black developer if necessary) to form a color image by superimposing toner images. Conventional electrophotographic toner (hereinafter simply referred to as "toner")
It may be called. ) Is obtained by mixing, melting and kneading a binder resin, a colorant, and, if necessary, a release agent and a charge controlling agent, and solidifying the mixture by cooling, and then pulverizing and classifying. Further, an external mixing step of attaching and fixing a fluidity-imparting agent, a charge controlling agent, a cleaning aid, a transfer aid, and the like to the toner surface, and a step of sieving and removing coarse substances generated in the external adding and mixing step. Is provided.

[0003] The color development of an electrophotographic toner is determined mainly by the coloring material dispersed in the kneading step. Poor dispersion of the coloring material causes light scattering and lowers the transparency of the toner. Therefore, O
The projected image of the toner image transferred and fixed to the film for the HP (overhead projector) is dark, the saturation is low, and the color reproduction range (color gamut) of an image obtained by superimposing a plurality of toners such as a full-color image The problem of narrowing occurs. To increase the transparency of the toner, Japanese Patent Application Laid-Open
273570, JP-A-64-29855,
And JP-A-1-284865, C.I. I. There is a proposal to increase the transparency using Solvent Blue 35, indophenol or anthraquinone dye. However, toners using these dyes have poor light resistance and are not practically used at present.

For the purpose of improving the light fastness, Japanese Patent Application Laid-Open No.
12838, JP-A-3-37026, JP-A-60-93453, JP-A-1-172973, JP-A-2-264264, JP-A-9-80
No. 797 discloses a proposal for incorporating an ultraviolet absorber or an antioxidant in a toner, but it does not sufficiently improve the light fastness, but also involves the incorporation of foreign substances. Scattering occurs, which ultimately reduces transparency. Therefore, most commercially available full-color toners use pigments as colorants.

[0005] From these, it is important for the full color toner for electrophotography to disperse the pigment to be used well, and efforts are being made to improve the dispersion by using various techniques, and the binder resin is replaced with moisture before drying. Flushing techniques, several-order kneading, and the like are widely used. In recent years, the use of polyester resins as binder resins has been increasing in many cases in order to reduce the particle size of toners for the purpose of improving image quality and to secure low-temperature fixability. When a polyester resin is used, an increase in pulverizing energy and a decrease in productivity due to a reduction in the diameter of the toner can be achieved by lowering the molecular weight of the binder resin without sacrificing low-temperature fixability. ing.

However, when a polyester resin is used, a problem occurs in the storability of an image. That is, in long-term storage in a bright place, irradiation of ultraviolet rays causes yellow stain of the resin itself, a shift from a desired color occurs, the image surface is disintegrated, and glossiness is remarkably reduced. In particular, when a cyan toner or a magenta toner having a large color difference from yellow is used, the color shift becomes large. JP-A-9-8
By simply adding an ultraviolet absorber as disclosed in JP-A-07797 to the toner, the light resistance of the coloring material is slightly improved, but the yellow stain of the binder resin itself is not improved. As a result, the color difference of the toner is reduced. The phenomenon of shifting occurs. Further, depending on the ultraviolet absorber used, the powder fluidity of the toner deteriorates, which is not suitable. As described above, the toner for the purpose of high image quality and low-temperature
At present, a product that satisfies all of transparency and powder fluidity has not yet been obtained.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, the present invention is a full-color image, high image quality, electrophotographic toner excellent in light resistance, transparency, powder fluidity, its production method, a two-component developer containing the electrophotographic toner, It is another object of the present invention to provide a color image forming method using the electrophotographic toner. Also,
The present invention provides, in addition to the above properties, an electrophotographic toner having excellent low-temperature fixability, a method for producing the same, a two-component developer containing the electrophotographic toner, and a color image using the electrophotographic toner. It is an object to provide a forming method.

[0008]

Means for solving the above problems are as follows. That is, <1> an electrophotographic toner containing a binder resin and a colorant as main components, contains an ultraviolet absorber having a melting point in the range of 90 to 150 ° C., and has a light transmittance of 65 or more. This is a toner for electrophotography. <2> In the method for producing an electrophotographic toner having a kneading step, the electrophotographic toner contains an ultraviolet absorber having a melting point in the range of 90 to 150 ° C., and the discharge temperature of the kneaded material in the kneading step is reduced. A method for producing a toner for electrophotography, wherein the ultraviolet absorber has a temperature in the range of (melting point−10 ° C.) to (melting point + 30 ° C.). <3> A two-component developer containing the electrophotographic toner according to <1> and a carrier. <4> a latent image forming step of forming an electrostatic latent image on the latent image carrier, a developing step of developing the electrostatic latent image with toner to form a toner image, and transferring the toner image to an intermediate transfer member In a color image forming method including a first transfer step of transferring and a second transfer step of transferring the toner image on the intermediate transfer member to a transfer material, the toner is the toner for electrophotography according to <1>. A color image forming method.

[0009] Further, means for solving the above problems include:
The following embodiments are preferred. <5> The electrophotographic toner according to <1>, wherein the binder resin is a polyester resin produced from a polyhydric alcohol component and a polycarboxylic acid. <6> The electrophotographic toner according to <1> or <5>, wherein the colorant is a blue pigment or a magenta pigment. <7> The blue pigment is C.I. I. Pigment
The electrophotographic toner according to <6>, wherein the toner is Blue 15: 3. <8> The magenta pigment is C.I. I. Pigmen
The electrophotographic toner according to <6>, wherein t Red is 57: 1. <9> The magenta pigment is C.I. I. Pigmen
The electrophotographic toner according to <6>, wherein t Red 122 is used. <10> The magenta pigment is C.I. I. Pigme
nt Red 57: 1 and C.I. I. Pigment R
The electrophotographic toner according to <6>, wherein the toner is a mixture of ed122.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. [Electrophotographic Toner] The electrophotographic toner of the present invention contains a binder resin, a colorant, and an ultraviolet absorber, and further contains other components as necessary. The toner for electrophotography of the present invention is characterized by containing an ultraviolet absorber having a specific melting point, whereby it has excellent light resistance, transparency and powder fluidity, and the transparency is light transmittance. Is 65 or more.

In the present invention, the light transmittance is a PE value, which is a total light of each wavelength in a visible light range of a sample formed on an OHP (overhead projector) film using an electrophotographic toner. The ratio between the transmitted light component and the straight light component is indicated by the following equation. PE = log (Σ [P (λ) + N (λ)] / n) / log (Σ [P (λ)] / n) (where P (λ) is a straight light component and N (λ) is Indicates the diffused light component.)

The method for measuring the light transmittance (PE value) is as follows.
It can be measured by using a DIANO match scan. Further, an apparatus that can measure the straight light component and the diffuse light component of each wavelength can be used. Although the electrophotographic toner of the present invention has a light transmittance of 65 or more,
70 or more is preferable, and 75 or more is more preferable. If the light transmittance is less than 65, the color developability decreases when an image is projected by the OHP. Further, the volume average particle diameter of the electrophotographic toner of the present invention is preferably 4 to 12 μm,
6 to 9 μm is more preferred.

(Binder Resin) The binder resin used in the present invention is not particularly limited, and any conventionally known binder resin may be used. Specifically, for example, styrenes such as styrene and chlorostyrene; ethylene, propylene,
Monoolefins such as butylene and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, Α-methylene aliphatic monocarboxylic esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl butyl ether; vinyl methyl ketone, vinyl hexyl ketone And vinyl ketones such as vinyl isopropenyl ketone; and homopolymers and copolymers such as polystyrene, styrene-alkyl acrylate copolymer, and styrene. Alkyl methacrylate copolymer,
Styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer,
Examples include polyethylene and polypropylene, and further include polyester resin, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin, and paraffin wax. These may be used alone or in combination of two or more. Among these, a binder resin having a structure and a molecular weight such that the softening point is in the range of 90 to 150 ° C. is more preferable. In the present invention, from the viewpoint of reducing the particle size of the toner and the low-temperature fixability, a polyester resin and a styrene-acrylic copolymer resin are preferable, and a polyester resin is particularly preferable.

The polyester resin used in the present invention comprises:
The number average molecular weight Mn is preferably from 2000 to 6000,
2500 to 4500 are more preferable, and the weight average molecular weight M
w is preferably 6000 to 40000, and 7000 to 3
0000 is more preferred. When the number average molecular weight is larger than 6000, the pulverizability is remarkably reduced and the productivity may be deteriorated. On the other hand, when the number average molecular weight is less than 2,000, the strength of the toner image is reduced, and The toner may be easily crushed or the fixed image may be cracked in the developing machine. If the weight average molecular weight is more than 40,000, the pulverizability may decrease and the productivity may deteriorate. On the other hand, if the weight average molecular weight is less than 6000, the molecular cohesion of the polyester decreases and the toner peels off. May deteriorate.

The polyester resin has a softening point of 90 to 90.
140 ° C is preferred, and 100 to 140 ° C is more preferred. When the softening point is lower than 90 ° C., the heat storage property may be deteriorated. On the other hand, if the softening point is higher than 140 ° C., the low-temperature fixability may deteriorate. The glass transition point of the binder resin is preferably from 55 to 75 ° C, more preferably from 55 to 70 ° C. When the glass transition point is lower than 55 ° C., the heat storage property may be deteriorated. On the other hand, when the glass transition point is higher than 75 ° C., the low-temperature fixability may be deteriorated.

The polyester resin used in the present invention comprises:
It is preferably produced from a polyhydric alcohol component and a polycarboxylic acid, in which case the light resistance effect of the resin is remarkably exhibited. As the polyhydric alcohol component, for example, as a dihydric alcohol component, ethylene glycol, propylene glycol, 1,4-butanediol,
2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,
6-hexanediol, neopentylene glycol, 1,
4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, and the like. Examples of the trivalent or higher alcohol component include glycerin, sorbitol, 1.4 sorbitan, and trimethylolpropane. These may be used alone or in combination of two or more. On the other hand, as the divalent carboxylic acid component to be condensed with the polyhydric alcohol component, for example, maleic acid, maleic anhydride, fumaric acid, phthalic acid, terephthalic acid, isophthalic acid, malonic acid, succinic acid, glutaric acid, dodecenyl succinic acid , N-octyl succinic acid and the lower alkyl esters of these acids. These may be used alone or in combination of two or more.

The above-mentioned softening point of the resin indicates a temperature at a melt viscosity of 1 × 10 ⁴ Pa · s on a temperature-apparent viscosity curve. Melt viscosity is measured by flow tester CFT-
It was determined by obtaining a temperature-apparent viscosity curve using Model 500F (manufactured by Shimadzu Corporation). The conditions are shown below. Heating rate 3 ° C / min Starting temperature 8 ° C Ultimate temperature 150 ° C Measurement interval 3 seconds Preheating time 300 seconds Cylinder pressure 9.8 × 10 ⁵ Pa Die hole diameter 1 mm Die length 1 mm

(Colorant) The colorant used in the present invention is:
All known coloring materials such as organic pigments, inorganic pigments, oil-soluble dyes and disperse dyes can be used, but organic pigments are preferably used from the viewpoint of the light resistance of the coloring material. For example, C.I. I.
Pigment Red 12: 2, C.I. I. Pigment Red 48: 1, C.I. I. Pigment Red 57: 1, C.I.
I. Pigment Red 122, C.I. I. Pigment Red 185, C.I. I. Pigment Red 186, C.I. I.
Pigment Yellow 12, C.I. I. Pigment Yellow 14, C.I. I. Pigment Yellow 17, C.I. I. Pigment Yellow 94, C.I. I. Pigment Yellow 9
7, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 3 and the like are typical examples.

When a blue color material or a magenta color material having a color difference from the yellow stain of the binder resin itself is used, the effect of light resistance of the toner becomes more remarkable. In particular, C.I. I. Pigment Blue 15:
3, C.I. I. Pigment Red 57: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 185
It becomes more remarkable when using such as. These colorants may be used alone or in combination of two or more. The amount of the colorant varies depending on the color, charge amount, particle size, etc. of the toner.
0% by weight is preferable, and 1 to 20% by weight is more preferable.
When the amount is more than 30% by weight, the transparency of the toner may be deteriorated even if the dispersion of the coloring material is improved. On the other hand, when the amount is less than 0.5% by weight, the coloring power becomes weak. In some cases, a sufficient effect cannot be exhibited.

In the present invention, when a dye is used as a coloring material, the surface collapse of an image due to ultraviolet irradiation is improved.
Although the light resistance of the coloring material is improved, it is not perfect.
The pigment to be used is a flushing product obtained by kneading the aqueous paste of the pigment and the binder resin at a temperature equal to or higher than the softening point of the resin at normal pressure and performing a flushing process, or a dry pigment of the colorant and the binder resin. It is a high-concentration pigment pellet produced by mixing by means of, for example, a heating type two or three rolls while applying high shearing force by heating and melting, and from the viewpoint of colorant dispersion, preferable.

(Ultraviolet absorber) The ultraviolet absorber used in the present invention is not particularly limited as long as it has a melting point in the range of 90 to 150 ° C., and conventionally known ones can be used. For example, benzotriazole-based, anilide-based, triazine-based, benzophenone-based, and benzoate-based powders or granules are used. Specifically, for example, 2,4-dihydroxybenzophenone (melting point 145 ° C.), 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid trihydrate (melting point 110 ° C.), 4-benzyloxy-2-hydroxybenzophenone (Melting point 120
° C), 2,2'-dihydroxy-4,4'-dimethoxybenzophenone (melting point 135 ° C), ethyl 2-cyano-
3,3′-diphenyl acrylate (melting point 97 ° C.), 2
-(2-hydroxy-5-methylphenyl) -2H-benzotriazole (mp 130 ° C.), 2- (3-tert-butyl-2-hydroxy-5-methylphenyl)-
5-chloro-2H-benzotrizole (mp 140
° C), 1,6-bis (4-benzoyl-3-hydroxyphenoxy) -hexane (melting point 145 ° C), 2- (5-
Methyl-2-hydroxyphenyl) benzotriazole (melting point 130 ° C), 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole (melting point 140 ° C), (3-t-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole (mp 140 ° C.), 2- (2 ′
-Hydroxy-5'-t-octylphenyl) benzotriazole (melting point 110 ° C), 2-ethoxy-2'-ethyl-oxalic acid bisanilide (melting point 125 ° C),
2- (4 ′, 6-diphenyl-1,3,5-triazin-2-yl) -5 [(hexyl) oxy] -phenol (mp 148 ° C.), 2- (3,5-di-t-butyl) -4
-Hydroxybenzyl) -2-n-butylmalonate bis (1,2,2,6,6-pentamethyl-4-piperidyl) (melting point: 148 ° C.), etc.
If it is an ultraviolet absorber in the range of 50 ° C., it is not limited to these. These may be used alone or in combination of two or more. If the melting point of the ultraviolet absorber used is less than 90 ° C., the powder fluidity of the toner will be extremely deteriorated. On the other hand, when the temperature exceeds 150 ° C., fixing failure occurs, and yellow stain of the binder resin occurs during storage. The melting point of the ultraviolet absorber is 90-1.
40 ° C. is more preferred.

The content of the ultraviolet absorber is preferably 0.1 to 10% by weight, more preferably 1 to 5% by weight in the toner. When the content is less than 0.1% by weight, the effect may not be exhibited. On the other hand, when the content is more than 10% by weight, the charging characteristic shifts to the plus side, and the toner is used as a negatively chargeable toner. Is not preferred.

(Other Components) -Internal Additives- A charge control agent and a release agent may be added as the other components to the toner of the present invention. Examples of the charge control agent include, in the case of negative charge, metal chelates of alkyl salicylic acid and naphthoic acid, and fluorine compounds described in JP-A-55-76353 and JP-A-3-213877. In the case of positive charge, quaternary ammonium salts and alkyl metal oxides described in JP-A-56-164350 are exemplified. As the release agent, for example, low molecular weight polyethylene, low molecular weight polypropylene, low molecular weight polyolefins such as polyethylene oxide, beeswax, carnauba wax, natural waxes such as montan wax, stearic acid, palmitic acid,
Higher fatty acids such as myristic acid and metal salts of higher fatty acids,
And higher fatty acid amides.

-External additives- The toner of the present invention may be subjected to an external additive such as a fluidizing agent or an auxiliary agent on the surface of the toner particles. As the external additive, silica fine particles whose surface is subjected to a hydrophobic treatment, titanium oxide fine particles,
Known fine particles such as inorganic fine particles such as alumina fine particles, cerium oxide fine particles, and carbon black, and polymer fine particles such as polycarbonate, polymethyl methacrylate, and silicone resin are exemplified.

The toner for electrophotography of the present invention having the above structure is
The toner can be suitably manufactured by a method for manufacturing an electrophotographic toner described below, but is not limited to this manufacturing method. In the method for producing an electrophotographic toner described below,
The above-listed binder resins, coloring agents, ultraviolet absorbers, and other components can be suitably used.

[Method of Manufacturing Electrophotographic Toner] The method of manufacturing an electrophotographic toner according to the present invention is a method of manufacturing an electrophotographic toner having a kneading step. Contains an ultraviolet absorber having a melting point in the range, the discharge temperature of the kneaded material in the kneading step,
(Melting point−10 ° C.) to (Melting point + 30)
° C). The toner for electrophotography of the present invention is produced by a kneading and pulverizing method. The kneading and pulverizing method is not particularly limited as long as it is a conventionally known one. Specifically, at least a kneaded toner-forming material is prepared. A pulverizing and classifying step of pulverizing and classifying the kneaded material to prepare toner particles, and at least an externally adding and mixing step of mixing an external additive with the toner particles. Depending on the other steps.
The method of adding the ultraviolet absorber to the toner is a method in which a binder resin and a colorant are mixed and added at the time of mixing before melt-kneading, a method of adding when manufacturing a flushing color material,
There is a method of adding at the time of several-order kneading.

In the present invention, a known one- or two-shaft extruder or a known one- or two-shaft kneader can be used. When using a twin-screw kneader, the directions of rotation of the screws may be different or the same.
At least the binder resin, the colorant and the ultraviolet absorber are mixed by the kneader so that the kneaded material discharge temperature is in the range of (melting point −10 ° C.) to (melting point + 30 ° C.) of the used ultraviolet absorber. When adjusted and kneaded, the effect appears more remarkably. If the kneaded material discharge temperature is lower than the melting point of the used ultraviolet absorber (-10 ° C.), the binder resin and the ultraviolet absorber are not sufficiently melt-mixed (poor in wettability), and the ultraviolet absorber is dispersed. This is because not only is the transparency of the toner not excellent, but also the light resistance of the binder resin is inferior. On the other hand, if the temperature at which the kneaded material is discharged exceeds the melting point of the UV absorber used (melting point + 30 ° C.), the viscosity during kneading is reduced together with the binder resin. And the mixing state of the toner and the ultraviolet absorber deteriorates, and the transparency and light resistance of the toner cannot be sufficiently obtained. In the present invention,
The kneaded material discharge temperature is more preferably from (melting point −5 ° C.) to (melting point + 25 ° C.) of the ultraviolet absorber used.

The kneaded material discharge temperature can be adjusted by adjusting the gap between the screw and the barrel, the screw shape, the kneading time, the number of rotations of the screw, the barrel temperature, and the like. A method of adding water during kneading to lower the temperature of the kneaded material and increase the shear by utilizing latent heat of evaporation is often used. The mixture thus kneaded is cooled and solidified, then crushed / crushed, crushed and classified, and adjusted to particles having a weight average particle size of 5 to 9 μm. Examples of the pulverizer / classifier used in the present invention include a known jet or mechanical pulverizer, and a known centrifugal or inertia classifier.

In the present invention, after the kneading step and the pulverizing and classifying step, as an external mixing step, inorganic fine particles such as silica, titania and alumina are added and mixed for the purpose of improving the fluidity of the toner and imparting chargeability. You may. As the inorganic fine particles, those obtained by treating the surface with a silane compound such as a silane coupling agent can be suitably used. External mixing can be performed by, for example, a V-type blender, a Henschel mixer, a Loedige mixer, or the like. At this time, various additives may be added as needed. These additives include other fluidizing agents, polystyrene fine particles, polymethyl methacrylate fine particles,
A cleaning aid such as polyvinylidene fluoride fine particles or a transfer aid is exemplified.

[Two-Component Developer] The two-component developer of the present invention is characterized by containing the electrophotographic toner of the present invention and a carrier. Carrier used in the present invention,
Known ones can be used. For example, iron oxide, nickel, copper, zinc, cobalt, manganese, magnesium, chromium, etc., metals, alloys, oxides and ferrites composed of the above-mentioned metals, and the like, and the carrier surface is coated with a resin or the like What was done can also be used. By using a resin-coated carrier as a carrier, it is possible to improve background rise and unevenness in density due to rising of charge and deterioration of charge distribution due to reduction in toner particle size, and decrease in charge amount.

As the coating resin, known thermoplastic resins can be used, and specific examples thereof include styrenes such as styrene, chlorostyrene and vinylstyrene; vinyl acetate, vinyl propionate, vinyl benzoate and butyric acid. Vinyl esters such as vinyl; methyl (meth) acrylate,
Α-methylene aliphatic monocarboxylic acid esters such as ethyl (meth) acrylate, butyl (meth) acrylate, dodecyl (meth) acrylate, octyl (meth) acrylate, and phenyl (meth) acrylate; vinyl methyl ether And vinyl ethers such as vinyl ethyl ether and vinyl butyl ether; and homopolymers or copolymers such as vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone.

Particularly, typical coating resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, and styrene- And maleic anhydride copolymers. Further, polyester resins, polyurethanes, epoxy resins, silicone resins, polyamides, modified rosins, paraffin waxes and the like, further include halogen-containing polymers, specifically, compounds containing fluorine in the side chain Preferred are, in particular, fluorinated alkyl acrylates and fluorinated alkyl methacrylates as representative compounds. Then, a fluorinated epoxy resin, a fluorinated polyester resin, a fluorinated silicone resin, or the like can also be used. These coating resins may be used alone or in combination of two or more.

[Color Image Forming Method] The toner for electrophotography of the present invention can be used in a conventionally known color image forming method. That is, the color image forming method of the present invention is a latent image forming step of forming an electrostatic latent image on a latent image carrier, and a developing step of developing the electrostatic latent image with toner to form a toner image, A color image forming method comprising: a first transfer step of transferring the toner image to an intermediate transfer member; and a second transfer step of transferring the toner image on the intermediate transfer member to a transfer material. The electrophotographic toner according to the present invention is characterized in that the toner is an electrophotographic toner. A color image obtained by the color image forming method of the present invention is excellent in light resistance because the toner of the present invention is used, and further excellent in transparency in a color image on OHP.

[0034]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.
In the following description, “parts” means “parts by weight”. (Example 1) Polyester resin (terephthalic acid / addition of ethylene oxide of bisphenol A / cyclohexanedimethanol = 50/25/25) 92 parts (Mw = 16000, Mn = 4300, Tg = 65) ° C, softening point Tm = 108 ° C)-UV absorber: 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole (melting point 110 ° C)・ ・ ・ ・ ・ 3 parts ・ Coloring agent: C.I. I. Pigment Blue 15: 3 5 parts The above composition was mixed and stirred with a 75 L Henschel mixer (manufactured by Mitsui Miike Co., Ltd.) to obtain a kneaded material. Next, the kneaded material was kneaded with a screw extruder TEM48BS (manufactured by Toshiba Machine Co., Ltd.) by adjusting the screw rotation speed and the amount of water added during kneading so that the kneaded material discharge temperature became 130 ° C. After rolling and cooling the obtained kneaded material, a fluidized bed pulverizer AFG4
Pulverized by 00 (manufactured by Alpine) and inertial classifier EJ30
To obtain a toner having a volume average particle size of 7.2 μm.
As an external additive to the toner particles,
Add 0.5 wt% of hexamethyldisilazane-treated silica having an average particle diameter of 40 nm, and 0.7 wt% of a titanium compound (average particle diameter of 30 nm) obtained by treating metatitanic acid with 50 wt% of isobutyltrimethoxysilane and calcining, and then add 75 L.
The mixture was mixed with a Henschel mixer for 10 minutes, and then sieved with a wind sieving machine Hibolter 300 (manufactured by Shin-Tokyo Machinery Co., Ltd.) to produce a toner A1. Further, in order to confirm the light resistance effect of only the binder resin, toner particles A2 were prepared with the same composition, apparatus, and conditions except that the colorant was removed from the above composition.

Example 2 Polyester resin (maleic acid / bisphenol A ethylene oxide adduct / propylene oxide adduct = 50/25/25) 90 parts (Mw = 20,000, Mn = 4700) , Tg = 68 ° C, softening point Tm = 111 ° C)-UV absorber: 2-ethoxy-2'-ethyl-oxalic acid bisanilide (melting point 125 ° C) ... 5 parts-Colorant: C.I. I. Pigment Red 57: 1 5 parts The above composition was adjusted using the same apparatus as in Example 1 except that the kneaded material discharge temperature was adjusted to 140 ° C. by the screw rotation speed. In the same manner as in Example 1, toner particles B1 having a volume average particle size of 7.5 μm were produced. Further, in order to confirm the light resistance effect of only the binder resin, toner particles B2 were prepared with the same composition, apparatus, and conditions except that the colorant was removed from the above composition.

(Example 3) Polyester resin (terephthalic acid / addition of ethylene oxide of bisphenol A / cyclohexanedimethanol = 50/25/25) 91 parts (Mw = 16000, Mn = 4300, (Tg = 65 ° C, softening point Tm = 108 ° C) ・ Ultraviolet absorber: 2,2′-dihydroxy-4,4′-dimethoxybenzophenone (melting point 135 ° C.) ... 2 parts-Colorant: C.I. I. Pigment Red 57: 1 3 parts Colorant: C.I. I. Pigment Red 122 ·········· 4 parts Example 1 except that the above composition was adjusted using the same apparatus as in Example 1 and the screw rotation speed was adjusted so that the kneaded material discharge temperature was 160 ° C. In the same manner as in the above, toner particles C1 having a volume average particle size of 6.5 μm were produced. Further, in order to confirm the light resistance effect of only the binder resin, toner particles C2 were prepared with the same composition, apparatus, and conditions except that the colorant was removed from the above composition.

Comparative Example 1 The procedure of Example 1 was repeated except that no ultraviolet absorber was contained and the weight of the polyester resin was 95%.
The toner particles P1 (with a coloring material) and the toner particles P2 (without a coloring material) were produced in the same manner as in Example 1 except that the toner particles P1 and P2 were used.

Comparative Example 2 Each of the toner particles Q1 (color) was prepared in the same manner as in Example 1 except that the ultraviolet absorber was changed to 2-hydroxy-4-methoxybenzophenone having a melting point of 64 ° C. Material) and toner particles Q2 (without color material).

Comparative Example 3 The procedure of Example 2 was repeated except that no ultraviolet absorber was contained and the weight of the polyester resin was 95%.
The toner particles R1 (with a coloring material) and the toner particles R2 (without a coloring material) were produced in the same manner as in Example 2 except that the toner particles R1 and R2 were used.

Comparative Example 4 The procedure of Example 2 was repeated, except that the UV absorber was changed to 2- (2-hydroxy-5-methylphenyl) -2H-benzotriazole having a melting point of 195 ° C. According to the method, toner particles S1 (with coloring material) and toner particles S2 (without coloring material) were produced.

Comparative Example 5 The same procedure as in Example 3 was repeated except that no ultraviolet absorber was contained and the weight of the polyester resin was 93
The toner particles T1 (with a color material) and the toner particles T2 (without a color material) were produced in the same manner as in Example 3 except that the toner particles were changed to parts.

[Preparation of carrier / preparation of developer] 0.1 part per 100 parts of ferrite core having an average particle size of 50 μm.
Five parts of vinylidene fluoride and 1.35 parts of a copolymer of methyl methacrylate and trifluoroethylene (polymerization ratio: 80:20) were coated with a kneader to prepare a carrier. The obtained carrier and each of the toners were mixed in a ratio of 100 parts: 8 parts by a 2 liter V blender to prepare 16 types of developers A1 to T2.

<Evaluation of Powder Fluidity> Of the obtained toner particles A1 to T2, the powder fluidity (compression ratio) of the toner particles containing a coloring material was measured by a powder tester, and according to the following criteria. evaluated. The results are shown in Table 1 below. The evaluation was as follows.
Less than 5 was rated as Δ, and 0.425 or more was rated as x.

<Evaluation of light resistance> The developer A1 obtained above
~ T2, A-Color936 modified machine
In an environment of 0 ° C and 50%, the toner weight on paper is 0.7 mg /
cm ² , and a 100% solid (5 × 5 cm) image was printed on each of the Fuji Xerox J paper and the Fuji Xerox OHP sheet in the single color mode. The density of the color of the paper sample (J paper made by Fuji Xerox) on which the image was drawn was measured using a densitometer (X-Rite 938: X-Ri).
The gloss of a paper sample measured and measured by a te company was measured using a gloss measuring device (Murakami Color Research Laboratory: 7).
5 degrees), and used as a reference color density and a reference gloss, respectively. In addition, the gloss was measured only when the image was rendered using a developer containing toner particles containing a coloring material. This paper sample was subjected to light resistance tester 2
Ultraviolet irradiation was performed for 00 hours (condition: xenon-arc light 100 klux), and the color density and gloss of the paper sample after the ultraviolet irradiation were measured in the same manner. From these measurements,
Color difference ΔE = [(L ₁ −
L ₂ ) ² + (a ₁ −a ₂ ) ² + (b ₁ −b ₂ ) ² ] ^1/2 , and the difference Δgloss (expressed by the following formula) between before and after ultraviolet irradiation. I asked. Further, ΔE of the toner with the color material
The difference between ΔE and the colorant-free toner is Δ (ΔE), which is the color change of the colorant.

[0045]

(Equation 1)

The results evaluated according to the following criteria are shown in Table 1 below.
Shown in Regarding the ΔE of the toner with a color material, ◎ is less than 5, を is 5 to less than 10, △ is 10 to less than 15,
The above is indicated by x, and ΔE and Δ (ΔE) of the toner without the colorant were evaluated based on １ ／ of the above value. Regarding Δgloss, ○ indicates 95% or more, Δ indicates 90% or more and less than 95%, and × indicates less than 90%.

<Evaluation of Transparency> The light transmittance (PE value) of an OHP sample (an OHP sheet manufactured by Fuji Xerox) on which a picture was formed was measured. For measurement, DIANO
The company's match scan was used. In addition, the light transmittance was measured only when the image was rendered using a developer containing toner particles containing a coloring material. The results evaluated according to the following criteria are shown in Table 1 below. The evaluation was evaluated as を for 75 or more, Δ for 65 or more and less than 75, and × for less than 65.

[0048]

[Table 1]

From the results shown in Table 1, it can be seen that the toners of Examples 1 to 3 of the present invention are excellent in powder fluidity. Further, it can be seen that when an image is formed on an OHP using the toner of the present invention, the transparency is excellent. Further, it can be seen that when an image is formed on paper using the toner of the present invention, color shift due to ultraviolet irradiation is small, good gloss can be maintained, and light resistance is excellent. On the other hand, with respect to the toners of Comparative Examples 1 to 5, those having no added ultraviolet absorber have poor light fastness, and those having added an ultraviolet absorber which is not the ultraviolet absorber specified in the present invention have transparency or powder. Poor body fluidity.

[0050]

According to the present invention, an electrophotographic toner having high image quality in full-color images and having excellent light resistance, transparency, and powder fluidity, a method for producing the same, and a method including the electrophotographic toner are provided. A component-based developer and a color image forming method using the electrophotographic toner can be provided. In particular, by using a polyester resin as the binder resin, the yellow stain of the resin itself due to ultraviolet irradiation is improved while maintaining low-temperature fixability, and color shift is small.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H005 AA06 AA21 AB03 CA08 DA05 DA10 FA01 2H032 AA15 BA05 BA07 2H077 AD06 EA01 GA13

Claims (4)

[Claims] 1. An electrophotographic toner mainly comprising a binder resin and a colorant, which contains an ultraviolet absorbent having a melting point in the range of 90 to 150 ° C. and has a light transmittance of 65 or more. A toner for electrophotography, comprising: 2. A method for producing an electrophotographic toner having a kneading step, wherein the electrophotographic toner is 90 to 150.
An ultraviolet absorbent having a melting point in the range of ° C. is contained, and the discharge temperature of the kneaded material in the kneading step is in the range of (melting point−10 ° C.) to (melting point + 30 ° C.) of the ultraviolet absorbent. Of producing an electrophotographic toner. 3. A two-component developer comprising the electrophotographic toner according to claim 1 and a carrier. 4. A latent image forming step of forming an electrostatic latent image on a latent image carrier, a developing step of developing the electrostatic latent image with toner to form a toner image, and an intermediate transfer of the toner image The electrophotographic toner according to claim 1, wherein the toner is a color image forming method including a first transfer step of transferring the toner image on an intermediate transfer member to a transfer material, and a second transfer step of transferring the toner image on an intermediate transfer member to a transfer material. A color image forming method.