JP4857995B2 - Color toner and image forming apparatus - Google Patents

Description

  The present invention relates to a color toner used for electrophotographic image formation and an image forming apparatus. More specifically, the present invention relates to a color toner for image fixing and an image forming apparatus for fixing on a recording sheet with light.

  In the electrophotographic system widely used in copying machines, printers, printing machines, etc., image formation is generally performed as follows. First, after a charging step that gives a positive or negative uniform electrostatic charge to the photoconductive insulator surface of the photosensitive drum, the surface of the insulator is irradiated with, for example, a laser beam, and the electrostatic charge on the insulator surface is reduced. An electrostatic latent image corresponding to image information is formed by partially erasing. Next, for example, a fine powder of a developer called toner is attached to the latent image portion on which the electrostatic charge remains on the photoconductive insulator, and the latent image is visualized as a toner image. In order to make the toner image thus obtained into a printed matter, generally, the toner image is electrostatically transferred to a recording medium such as recording paper, and then the toner image is fixed to the recording medium.

  For fixing the toner image after the transfer, a method of solidifying and fixing after melting the toner by pressure, heating, or a method using a combination thereof, or a method of solidifying and fixing after melting the toner by irradiating light energy However, a light fixing method (also called a flash fixing method) using light that does not cause harmful effects due to pressure or heating has attracted attention.

  That is, in the photofixing method, since it is not necessary to pressurize the toner when fixing the toner, it is not necessary to make contact (pressurization) with a fixing roller or the like, and there is little deterioration in image resolution (reproducibility) in the fixing process. There are advantages. In addition, since there is no need to heat with a heat source or the like, printing does not occur until the heat source (such as a fixing roller) is preheated to a desired temperature after the power is turned on. Yes. In addition, since a high-temperature heat source is not required, there is an advantage that the temperature rise in the apparatus can be appropriately avoided, and even when a recording paper jam occurs in the fixing device due to a system down, The recording paper is not altered or blackened by heat.

  On the other hand, in recent years, full-color images obtained by electrophotography have been increasingly demanded for high speed, high image quality, and high definition. This tendency is particularly noticeable in the case of professional users who are familiar with printing, and until now it has not been possible to accept a full color image by electrophotography as a sufficiently satisfactory image.

  In particular, the image forming apparatus using the above-described photofixing method is a non-contact fixing method, so that it is a full color equivalent to printing on a high-speed machine with a process speed of 1000 mm / second or more (equivalent to 400 sheets of A4 equivalent per minute) or more. Applications that reproduce image quality over a long period are required. In a high-speed machine having a process speed of 1000 / second or more, it is difficult to use a general-purpose organic photoconductor because of the response speed of the photoconductor as a latent image carrier, and amorphous silicon is usually used as the photoconductor. However, since the amorphous silicon photosensitive layer has a low electric resistance, the latent image cannot be sufficiently held, and the image is blurred and fogging occurs. This point tended to be particularly noticeable when combined with cyan toner.

  Heretofore, as a blue colorant for color toner for light fixing, particularly flash fixing, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 60 has been proposed (see, for example, Patent Document 1), but there is no examination example including the above-described problems when high-speed printing is performed using amorphous silicon as a photoreceptor.

Further, when the light fixing method is used for fixing a color toner, the fixing property is lower than that for fixing a normal black toner (black toner) due to the low light absorption efficiency of the color toner. Therefore, many proposals have been made to improve the fixing property by adding an infrared absorber to the color toner (for example, see Patent Documents 2 to 4). However, since known infrared absorbers for toner have black, brown and green color, when added to a color toner, the color tone of the toner is greatly affected. The color tone of the image after fixing fluctuates with respect to the standard of the color gamut represented, and it was impossible to achieve both fixing property and sufficient color reproducibility.
Japanese Patent Laid-Open No. 2003-66654 JP 60-63545 A JP-A-60-57858 JP-A-60-131544

The object of the present invention is to solve the above-mentioned problems of the prior art.
That is, an object of the present invention is to use a color toner that can achieve both color reproducibility and high fixability without causing fog and image blur even when amorphous silicon is used as a photoreceptor, and the same. An object is to provide an image forming apparatus.

The above-mentioned subject is achieved by the following present invention. That is, the present invention
<1> A color toner including at least a binder resin, a plurality of colorants, and an infrared absorber,
The plurality of colorants include at least pigment A and pigment B, and the pigment A is C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, the pigment B is an indanthrone pigment represented by the following structural formula (I), and the mixing ratio of the pigment A and the pigment B contained (mass of pigment B / (Sum of the mass of pigment A and the mass of pigment B)) is a color toner in the range of 0.03 to 0.8.

<2> A latent image carrier, a developing unit that forms a toner image on the latent image carrier using a color toner for light fixing, a transfer unit that transfers the toner image onto a recording medium, An image forming apparatus having fixing means for light-fixing a toner image on a recording medium with light,
The color toner for light fixing includes at least a binder resin, a plurality of colorants, and an infrared absorber, and the plurality of colorants include at least pigment A and pigment B. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: is any of the four, the pigment B is indanthrone pigments represented by the following Symbol structural formula (I), the mass mixing ratio (pigment B of pigment A and pigment B contained / (Sum of the mass of pigment A and the mass of pigment B)) is in the range of 0.03 to 0.8, the latent image carrier is amorphous silicon, and the process speed is 1000 mm / second or more and 3000 mm / This is an image forming apparatus that is less than a second.

  According to the present invention, even when amorphous silicon is used as a photoreceptor, color toner that does not cause fogging and image blur and can achieve both color reproducibility and high fixability, and image formation using the same An apparatus can be provided.

Hereinafter, the present invention will be described in detail.
<Color toner>
The color toner of the present invention is a color toner including at least a binder resin, a plurality of colorants and an infrared absorber, wherein the plurality of colorants include at least pigment A and pigment B. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, the pigment B is an indanthrone pigment represented by the following structural formula (I), and the mixing ratio of the pigment A and the pigment B contained (mass of pigment B / (Sum of the mass of pigment A and the mass of pigment B)) is in the range of 0.03 to 0.8.

The color toner of the present invention (hereinafter sometimes simply referred to as “toner”) is basically electrophotographic except that the pigment A and the pigment B are blended at a constant ratio as a colorant and further contains an infrared absorber. The composition can be the same as that of a color toner conventionally used in the process. The color toner of the present invention may be a magnetic toner having its own magnetism or a non-magnetic toner depending on the developing method employed in the electrophotographic process in which it is to be used. There may be. In the present invention, the term “color toner” mainly means cyan toner, but includes toners of other colors as long as the pigment A and the pigment B are included in a certain mass ratio described later.
In addition, the color toner of the present invention can be used for general-purpose heat roll fixing or light fixing. In particular, the performance described below can be exhibited when performing light fixing.

  The color toner of the present invention is preferably applied to an image forming apparatus using amorphous silicon as a photoreceptor. As the color tone of the color toner image, the goal is to reproduce Japan color standard colorimetric values. Here, Japan Color was established mainly by the ISO / TC130 National Committee and is a common color index as a color standard tool in offset sheet-fed printing.

In this case, the target values of the L ^* a ^* b ^* color system for cyan toner are L ^* of 59, a ^* of −24, and b ^* of −41. As shown in FIG. It can be seen that these values vary considerably depending on the type of blue pigment used for. In the figure, “PB” is an abbreviation for “CI Pigment Blue”. As can be seen from FIG. 1, examples of the single pigment include C.I. I. It can be said that Pigment Blue 15: 3 is closest to the target value.

  However, the above C.I. I. When phthalocyanine pigments including Pigment Blue 15: 3 were used as a colorant for cyan toner, it was found that image blurring and fogging occurred in image formation using the amorphous silicon as a photoreceptor. . As a result of intensive studies by the present inventors, the cause is that the electrical resistance of the phthalocyanine pigment is low, which also reduces the electrical resistance of the toner, and the toner image formed on the amorphous silicon surface having a low surface resistance. It was found that this was because image stability and the like deteriorated.

  On the other hand, when the present inventors further investigated, when the industron pigment represented by the following structural formula (I) was used as the same blue pigment, the above-mentioned image blur did not occur, and the reason This is because the electrical resistance value of the pigment itself is higher than that of the phthalocyanine pigment.

  From the above knowledge and the color tone of the Indanthrone pigment as shown in FIG. 1 is not greatly deviated from the color value on the standard side of Japan color (Industron pigment is indicated by “PB60” in the figure). In the invention, an attempt was made to achieve both reduction in image quality defects, color reproducibility and high fixability when using an amorphous silicon photoconductor by refining the mixing ratio of the phthalocyanine pigment and the indanthrone pigment. As a result, it has been found that all the above characteristics are satisfied when the mixing ratio is constant.

  Specifically, as phthalocyanine pigment A, C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4 is selected, and when the Indanthrone pigment is selected as the pigment B and mixed to form a color toner colorant, the blending ratio of the pigment A and the pigment B ( The mass of the pigment B / (sum of the mass of the pigment A and the mass of the pigment B) needs to be in the range of 0.03 to 0.8.

When the content of the pigment A is increased and the blending ratio is less than 0.03, the electric resistance value (volume resistivity) of the toner is lowered, and image blurring, high temperature and high humidity fog, etc. are caused by image formation on the amorphous silicon photoreceptor. Will occur. On the other hand, if the content of the pigment B increases and the blending ratio exceeds 0.8, the deviation of the color tone after fixing from the Japan color target value becomes too large.
The blending ratio is preferably in the range of 0.05 to 0.5, and more preferably in the range of 0.1 to 0.3.

The volume resistivity of the toner obtained by adjusting the mixing ratio of the pigment A and the pigment B is preferably in the range of 5 × 10 ^{14 to} 5 × 10 ¹⁵ Ωcm. If the volume resistivity is less than 5 × 10 ¹⁴ Ωcm, image blurring and high-temperature and high-humidity fogging may occur in image formation using an amorphous silicon photoreceptor. If it exceeds 5 × 10 ¹⁵ Ωcm, the content of the pigment as the colorant may be insufficient and a sufficient image density may not be obtained.

The volume resistivity of the toner was determined as follows. First, 4 g of toner was weighed, and a disk-shaped sample having a thickness of about 2 mm and a diameter of about 5 cm was prepared using a compression molding machine. Next, this disk-shaped sample was seasoned for 10 hours under high temperature and high humidity (28 ° C., 85% RH), and then placed on a conduction board of a digital ultrahigh resistance meter (R8340A, manufactured by Advantest) and sandwiched between probes. The volume electrical resistance of the toner was calculated using the following formula (1) from the reading of the resistance value when a voltage of 500 V was applied and the disc thickness measured in advance.
Volume resistivity (Ωcm) = 0.273 (reading value of ohmmeter (Ω)) / thickness of disk-shaped sample (cm) Formula (1)

Further, the color tone after fixing of the obtained toner is preferably 5 or less in color difference ΔE with respect to the target value of the L ^* a ^* b ^* color system of the Japan color. If ΔE exceeds 5, the impression of the image particularly when forming a full-color image may be deteriorated.

The color difference ΔE was determined from the following equation (2) by measuring L ^* , a ^* , and b ^* with a spectrometer (938 Spectrodentitometer, X-Rite) for a solid image of the target color toner alone.
ΔE = {(L ₀ ^* −L ₁ ^* ) ² + (a ₀ ^* −a ₁ ^* ) ² + (b ₀ ^* −b ₁ ^* ) ² } ^1/2 Formula (2)
Here, L ₀ ^* , a ₀ ^* , and b ₀ ^* are Japan color color reproducibility target values, and L ₁ ^* , a ₁ ^* , and b ₁ ^* are toner image measurement values.

  Next, the configuration of the color toner of the present invention will be described in detail. In the following description, the color toner of the present invention will be described as being representative of cyan toner. However, in the image forming apparatus of the present invention described later, in addition to the cyan toner, magenta toner, yellow toner, It is necessary to use black toner. Therefore, the following description will be made including the above toners in addition to the color toner of the present invention (basically, the toners other than the cyan toner are the same except that the colorant of the cyan toner is changed to each colorant described later. Is).

(Binder resin)
As the binder resin in the present invention, a known binder resin can be used. The main component of the binder resin is preferably polyester or polyolefin, but a copolymer of styrene and acrylic acid or methacrylic acid, polyvinyl chloride, phenol resin, acrylic resin, methacrylic resin, polyvinyl acetate, silicone resin, polyester. Resin, polyurethane, polyamide resin, furan resin, epoxy resin, xylene resin, polyvinyl butyral, terpene resin, coumarone indene resin, petroleum resin, polyether polyol resin, and the like can be used alone or in combination. From the viewpoints of durability and translucency, it is preferable to use a polyester resin or a norbornene polyolefin resin.

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

  In addition, such a polyester resin is usually one in which 80 mol% or more of the alcohol component is composed of a bisphenol A alkylene oxide adduct, preferably 90 mol% or more, and more preferably 95 mol% or more. . If the amount of the bisphenol A alkylene oxide adduct is less than 80 mol%, the amount of monomer used that causes odor relatively increases, which is not preferable.

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

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

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

Further, in the reaction for synthesizing such a polyester resin, a commonly used esterification catalyst such as zinc oxide, stannous oxide, dibutyltin oxide, dibutyltin dilaurate, etc. is advantageously used in order to accelerate the reaction. Can be used.
The Tg (glass transition point) of the binder resin used for the toner described above is preferably in the range of 50 to 70 ° C.

(Coloring agent)
As the colorant, those shown below can be appropriately selected and used according to the color of the toner.
The cyan toner that is the color toner of the present invention contains a plurality of colorants. The essential colorant is C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, Pigment A (phthalocyanine pigment), and Pigment B, which is an indanthrone pigment represented by the structural formula (I). The mixing ratio of the pigment A and the pigment B is as described above.

  As the pigment A, among the four phthalocyanine pigments, C.I. I. It is preferable to use Pigment Blue 15: 3. Indanthrone pigment which is pigment B is C.I. I. Pigment Blue 60 is classified into α type, β type, γ type, and δ type as crystal types. Of these, α-type and / or δ-type are preferably used in the present invention.

In the cyan toner, in addition to the pigment A and the pigment B, other colorants can be used in combination. Examples of the colorant include C.I. I. Pigment Blue 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 13, 16, 16, 17, 23, 60, the same 65, 73, 83, 180, C.I. I. Vat cyan 1, 3 and 20, etc., bitumen, cobalt blue, alkali blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, first sky blue, indanthrene blue BC cyan pigment, C.I. I. Cyan dyes such as solvent cyan 79 and 162 can be used.
When these are used in combination, the content is preferably in the range of 0.5 to 5 parts by mass with respect to 100 parts by mass of pigment A and pigment B.

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

  Similarly, in yellow toner, as the colorant, for example, C.I. I. Pigment Yellow 2, 3, 15, 15, 17, 74, 97, 180, 185, 139, and the like can be used.

The addition amount (total amount) of each colorant in the color toner of the present invention is preferably in the range of 2 to 15 parts by mass with respect to 100 parts by mass of final toner particles prepared by mixing with a binder resin or the like. 3 to 7 parts by mass is more preferable. If the amount is less than 2 parts by mass, the coloring power of the toner may be reduced. If the amount is more than 15 parts by mass, the transparency may be reduced and the reproducibility of the intermediate color may be reduced.
The same applies to the amount of colorant added to the magenta toner and yellow toner.

(Infrared absorber)
In the present invention, the infrared absorber added to the toner refers to a material having at least one strong light absorption peak in the near infrared region in the wavelength range of 800 to 2000 nm. It can be used.
As a specific example, a known infrared absorber can be used in combination, for example, cyanine compound, merocyanine compound, benzenethiol metal complex, mercaptophenol metal complex, aromatic diamine metal complex, diimonium compound, aminium compound, Nickel complex compounds, phthalocyanine compounds, anthraquinone compounds, naphthalocyanine compounds, and the like can be used.

  Among these, in the present invention, as described later, it is preferable to produce a color toner by preparing a master batch, and therefore it is preferable to use a thermally stable one. Specific examples include cyanine-based infrared absorbers (trade names: CTP-1, IRF-106, IRF-107, manufactured by Fuji Photo Film Co., Ltd.), dian compounds (trade names: CY-2, CY, manufactured by Nippon Kayaku Co., Ltd.). -4, CY-9) and the like.

  Furthermore, nickel metal complex infrared absorbers (Mitsui Chemicals, trade names: SIR-130, SIR-132), bis (dithiobenzyl) nickel (Midori Chemicals, trade name: MIR-101), bis [1 , 2-bis (p-methoxyphenyl) -1,2-ethylenedithiolate] nickel (manufactured by Midori Chemical Co., Ltd., trade name: MIR-102), tetra-n-butylammonium bis (cis-1,2-diphenyl- 1,2-ethylenedithiolate) nickel (manufactured by Midori Chemical Co., Ltd., trade name: MIR-1011), tetra-n-butylammonium bis [1,2-bis (p-methoxyphenyl) -1,2-ethylenedithiolate ] Nickel (manufactured by Midori Chemical Co., Ltd., trade name: MIR-1021), bis (4-tert-1,2-butyl-1,2-dithiophenolate) ni Kel-tetra-n-butylammonium (manufactured by Sumitomo Seika Co., Ltd., trade name: BBDT-NI), soluble phthalocyanine (manufactured by Nippon Shokubai Co., Ltd .: TX-305A), naphthalocyanine (manufactured by Sanyo Pigment Co., Ltd., SnNc FT-1), Examples thereof include inorganic material systems (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: ytterbium UU-HP; manufactured by Sumitomo Metals Co., Ltd., indium tin oxide). These can be used in combination of two or more.

Since these infrared absorbers greatly affect the color tone of the color toner as described above, it is desirable to reduce the amount of the infrared absorber added as much as possible. In the color toner of the present invention, by mixing and using the Indanthrone pigment as the pigment B, it is possible to increase the volume resistivity of the toner and also increase the absorption in the near infrared region. Therefore, it becomes possible to reduce the addition amount of the infrared absorber.
From such a viewpoint, in the color toner of the present invention, the addition amount of the infrared absorber used in combination with the pigment A and the pigment B is in the range of 0.01 to 3% by mass in the total amount of the toner components. Is preferred.

(Other ingredients)
The color toner of the present invention can use a charge control agent and wax as necessary.
As the charge control agent, known calixarene, nigrosine dyes, quaternary ammonium salts, amino group-containing polymers, metal-containing azo dyes, salicylic acid complex compounds, phenol compounds, azochromes, azozincs, and the like can be used. In addition, magnetic materials such as iron powder, magnetite, and ferrite can be mixed in the toner, and magnetic toner can be used. In particular, in the case of a color toner, a known white magnetic powder (for example, manufactured by Nippon Steel Mining Co., Ltd.) can be used.

  As the wax to be contained in the color toner of the present invention, ester wax, polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene is most preferable, but polyglycerin wax, microcrystalline wax, paraffin wax, carnauba wax, sasol wax, montan. Acid ester wax, deacidified carnauba wax, palmitic acid, stearic acid, montanic acid, brandic acid, eleostearic acid, valinalic acid and other unsaturated fatty acids, stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnauvyl alcohol, seryl alcohol , Saturated alcohols such as melylsil alcohol, or long-chain alkyl alcohols having a long-chain alkyl group; polyhydric alcohols such as sorbitol Fatty acid amides such as linoleic acid amide, oleic acid amide, lauric acid amide; saturated fatty acid bisamides such as methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, hexamethylene bis stearic acid amide, Unsaturated fatty acid amides such as ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; m-xylene bisstearic acid amide , N, N′-distearylisophthalic acid amides and other aromatic bisamides; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally referred to as metal soap); aliphatic Charcoal Waxes grafted onto vinyl waxes using vinyl monomers such as styrene and acrylic acid; Fatty acids such as behenic acid monoglycerides and partially esterified products of polyhydric alcohols; Hydroxyl groups obtained by hydrogenation of vegetable oils and fats And methyl ester compounds having

  The wax that can be used for the color toner of the present invention is preferably ester wax, polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene, but has an endothermic peak at 50 to 90 ° C. in DSC measurement (differential scanning calorimetry). The wax material shown is preferred. When the endothermic peak is lower than 50 ° C., the toner blocks, and when it is higher than 90 ° C., it may not contribute to fixing. In the DSC measurement, from the measurement principle, it is preferable to measure with a differential scanning calorimeter of high accuracy internal heat type input compensation type.

  These waxes can be used alone or in combination of two or more. The addition amount of the wax in the present invention is preferably in the range of 0.1 to 10% by mass and more preferably in the range of 1 to 4% by mass in the total amount of the toner constituents finally produced. .

  In producing the color toner of the present invention as described above, a commonly used kneading and pulverizing method, wet granulation method or the like can be used. Here, as the wet granulation method, suspension polymerization method, emulsion polymerization method, emulsion polymerization aggregation method, soap-free emulsion polymerization method, non-aqueous dispersion polymerization method, in-situ polymerization method, interfacial polymerization method, emulsion dispersion granulation The law etc. can be used.

  In order to produce the color toner of the present invention by the kneading and pulverization method, a binder resin, an infrared absorber, an antioxidant, a wax, a charge control agent, a pigment or dye as a colorant, and other additives, While mixing well with a mixer such as a Henschel mixer, ball mill, etc., and melt-kneading using a heat kneader such as a heating roll, kneader, extruder, etc., the resins are compatible with each other, an infrared absorber, an antioxidant, A toner can be obtained by dispersing or dissolving pigments, dyes, magnetic materials, etc., cooling and solidifying, and then performing pulverization and classification. Moreover, in order to improve the dispersibility of a pigment or an infrared absorber, you may perform a masterbatch.

On the other hand, as a wet granulation method, for example, when prepared by an emulsion polymerization method, first, a monomer such as styrene, butyl acrylate, or 2-ethylhexyl acrylate is dissolved in water in which a water-soluble polymerization initiator such as potassium persulfate is dissolved. In addition, a surfactant such as sodium dodecyl sulfate is added as necessary, and polymerization is performed by heating while stirring to obtain resin particles (resin particle forming step).
Thereafter, in addition to the colorant and infrared absorber described above, if necessary, a powder such as a charge control agent and a wax composition is added to the suspension in which the resin particles are dispersed, and the pH, stirring strength, and temperature of the suspension are added. By adjusting the above, the resin particles, the colorant powder, the infrared absorbent powder and the like are heteroaggregated to obtain a heteroaggregate (aggregation step). Furthermore, the reaction system is heated to a temperature higher than the glass transition temperature of the resin particles to fuse the heteroaggregates to obtain colored particles (fusion process). Thereafter, the colored particles are washed and dried, and an external additive is added as necessary to obtain the color toner of the present invention.

  In the present invention, as described above, it is preferable to use a polyester resin as the binder resin. When the toner particles are formed by a wet method using the polyester resin as the binder resin, the emulsion aggregation method is employed. be able to. In this case, the resin particle forming step is performed by applying a shear force to a solution obtained by mixing, for example, an aqueous medium, a sulfonated polyester resin and a mixed solution (polymer solution) containing a colorant as necessary. By giving an emulsified particle forming step of forming emulsified particles (droplets) by giving, colored particles can be similarly produced. The shape of the toner can be changed from a true sphere to a tuft of grapes.

The toner particles obtained by the above production method preferably have a volume average particle diameter D50v of 3 to 15 μm, more preferably 5 to 15 μm, and particularly preferably 5 to 10 μm.
When the volume average particle diameter of the toner particles exceeds 15 μm, the toner particle diameter is large and an image with sufficient resolution cannot be obtained. On the other hand, when the thickness is less than 3 μm, the resolution of the obtained image is high, but the fluidity is low, so the image is not stable, which causes fogging and poor cleaning.

  The ratio of the volume average particle diameter Dv to the number average particle diameter D50p (D50v / D50p) is preferably in the range of 1.0 to 1.25. By using toner having a small particle size and a uniform particle size, variations in the charging performance of the toner are suppressed, fog in the formed image is reduced, and toner fixability is improved. Can be made. Further, fine line reproducibility and dot reproducibility in the formed image can be improved.

The average circularity of the toner particles is preferably 0.955 or more, and more preferably 0.960 or more. Further, the standard deviation of the circularity is preferably 0.040 or less, and more preferably 0.038 or less. In this way, since each toner can be superposed on the recording medium in a dense state, the toner layer thickness on the recording medium can be reduced and the fixability can be improved. Further, by aligning the shape of the toner in this way, the fog, fine line reproducibility and dot reproducibility in the formed image are improved.
The average circularity of the toner particles is determined by using a flow type particle image analyzer (manufactured by Simex Co., Ltd., FPIA2000) and the peripheral length (perimeter length) of the projected image of the toner particles in the water dispersion system and the projected area of the toner particles. Is calculated by (circle equivalent perimeter / perimeter).

The color toner of the present invention can be used by mixing white inorganic fine particles with toner particles for a fluidity improver or the like. The mixing ratio with the toner particles is in the range of 0.01 to 5 parts by mass, preferably in the range of 0.01 to 2.0 parts by mass, with respect to 100 parts by mass of the toner particles. Examples of such inorganic fine powder include silica fine powder, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, and diatomaceous earth. Soil, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like can be mentioned, and silica fine powder is particularly preferable. Moreover, well-known materials, such as a silica, titanium, resin fine powder, an alumina, can be used together. Further, as a cleaning activator, a metal salt of a higher fatty acid typified by zinc stearate and a fine powder of a fluorine-based high molecular weight substance may be added.
The toner in the present invention can be obtained by sufficiently mixing the inorganic fine particles and, if necessary, desired additives with a mixer such as a Henschel mixer.

An electrophotographic developer containing the color toner of the present invention (hereinafter sometimes abbreviated as “developer”) is a one-component developer composed of the toner or a two-component developer composed of a carrier and the toner. Either may be sufficient.
Examples of the carrier used as a two-component developer include a resin-coated carrier having a resin coating layer on the core material surface. As the core material, known magnetite, ferrite, and iron powder can be used. The carrier coating agent is not particularly limited, but a silicone resin system is particularly desirable.

  The image forming method using the color toner of the present invention is not particularly limited. For example, a step of forming an electrostatic latent image on the surface of the electrostatic latent image carrier and a developer containing the formed electrostatic latent image with toner. Developing the toner image to form a toner image, transferring the formed toner image to the surface of the recording medium, fixing the toner image transferred to the surface of the recording medium to the surface of the recording medium, and forming an image And a fixing step. In this case, the fixing step may be performed by heating / pressing or by light.

<Image forming apparatus>
The image forming apparatus of the present invention is not particularly limited as long as it can form a full color image or the like on the recording medium using the toner containing the color toner on the recording medium using the developer containing the color toner of the present invention described above. Specifically, a developing means for forming a toner image on amorphous silicon as a latent image carrier, a transfer means for transferring the toner image onto a recording medium, and the transferred toner image by light as described below. A fixing means for optically fixing the recording medium, and a process speed of 1000 mm / second.
In this case, as the developer, a developer containing the cyan toner which is the color toner of the present invention is always used, and usually used in combination with a developer containing toners of other colors such as magenta, yellow and black. It is done.

  The image can be formed using amorphous silicon as an electrophotographic photosensitive member as a latent image carrier, for example, as follows. First, the surface of the electrophotographic photosensitive member is uniformly charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic latent image. Next, the toner is attached to the electrostatic latent image by contacting or approaching with a developing roll (developing means) having a developer layer formed on the surface, thereby forming a toner image on the electrophotographic photosensitive member. The formed toner image is transferred onto the surface of a recording medium such as paper using a corotron charger (transfer means). Further, the toner image transferred to the surface of the recording medium is optically fixed by a fixing device, and an image is formed on the recording medium.

As the electrophotographic photosensitive member, an amorphous silicon photosensitive member is used because it can cope with a high-speed process of 1000 mm / second or more and has a long life.
Further, as the fixing device, an optical fixing device (flash fixing device) is used because it can cope with the high-speed process of 1000 mm / second.

Examples of the light source used in the optical fixing device include a normal halogen lamp, a mercury lamp, a flash lamp, an infrared laser, and the like, and it is optimal because energy can be saved by instantaneously fixing with a flash lamp. Preferably emission energy of the flash lamp is in the range of 1.0~7.0J / cm ^2, and more preferably in the range of 2~5J / cm ^2.

Here, the emission energy per unit area of the flash light indicating the lamp intensity of xenon is expressed by the following formula (3).
S = ((1/2) × C × V ² ) / (u × L) × (n × f) (3)
In the above formula (3), n is the number of lamps that emit light at once (f), f is the lighting frequency (Hz), V is the input voltage (V), C is the capacitor capacity (F), u is the process transport speed (cm) / S), L represents the effective light emission width of the flash lamp (usually the maximum paper width, cm), and S represents the energy density (J / cm ² ).

The light fixing method is preferably a delay method in which a plurality of flash lamps emit light with a time difference. This delay system is a system in which a plurality of flash lamps are arranged, each lamp is delayed by about 0.01 to 100 ms, light is emitted, and the same portion is illuminated a plurality of times. As a result, the light energy can be divided and supplied to the toner image with a single light emission, so that the fixing conditions can be made mild and both void resistance and fixability can be achieved.
Here, when flash emission is performed on the toner a plurality of times, the emission energy of the flash lamp indicates the total amount of emission energy given to the unit area for each emission.

In the present invention, the number of flash lamps is preferably in the range of 1-20, and more preferably in the range of 2-10. Moreover, it is preferable that each time difference between several flash lamps is the range of 0.1-20 msec, and it is more preferable that it is the range of 1-3 msec.
Furthermore, once emission energy of light emitted in one flash lamp is preferably in the range of 0.1~1J / cm ^2, more preferably in the range of 0.4~0.8J / cm ^2.

Hereinafter, as an example of the image forming apparatus of the present invention, an image forming apparatus provided with a light fixing device (light fixing device) will be described with reference to the drawings.
FIG. 2 is a schematic diagram illustrating an example of the image forming apparatus. FIG. 2 shows a toner image formed by toner obtained by adding black to three colors of cyan, magenta, and yellow.

  2, 1a to 1d are charging means, 2a to 2d are exposure means, 3a to 3d are photosensitive members (latent image carriers), 4a to 4d are developing means, and 10 is a recording sent from the roll medium 15 in the direction of the arrow. Paper (recording medium), 20 is a cyan developing unit, 30 is a magenta developing unit, 40 is a yellow developing unit, 50 is a black developing unit, 70a to 70d are transfer rolls (transfer means), 71 and 72 are rolls, and 80 is a transfer Voltage supply means 90 represents an optical fixing device (fixing means).

  The image forming apparatus shown in FIG. 2 is disposed in contact with a recording sheet 10 and a developing unit for each color indicated by reference numerals 20, 30, 40, and 50 including a charging unit, an exposure unit, a photosensitive member, and a developing unit. Rolls 71 and 72 for transporting the paper 10, transfer rolls 70a, 70b, 70c and 70d arranged so as to be in contact with the opposite side through the recording paper 10 so as to press the photoreceptor of each developing unit, Light for irradiating light to the side of the recording paper 10 that contacts the photoconductor of the recording paper 10 that passes through the nip portion between the photoconductor and the transfer roll in the direction of the arrow in the figure. And a fixing device (fixing means) 90.

  The cyan developing unit 20 has a configuration in which a charging unit 1a, an exposing unit 2a, and a developing unit 4a are arranged around the photoreceptor 3a in a clockwise direction. Further, the transfer roll 70a is opposed to the photosensitive member 3a through the recording paper 10 so as to come into contact with the surface of the photosensitive member 3a from the position where the developing unit 4a of the photosensitive member 3a is arranged until the charging unit 1a is arranged clockwise. Has been placed. Such a configuration is the same for the developing units of other colors. In the image forming apparatus of the present invention, the developer containing cyan toner is accommodated in the developing means 4a of the cyan developing unit 20, and the developing means of the other developing units have light fixing corresponding to each color. A developer containing toner for use is stored.

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

  The toner images of the respective colors formed on the surface of the photoreceptor are sequentially transferred onto the recording paper 10 conveyed in the direction of the arrow by the action of the transfer potential by the transfer rolls 70a to 70d, and recorded so as to correspond to the original image information. A full-color laminated toner image is formed on the surface of the paper 10 and laminated in the order of cyan, magenta and yellow from the top layer.

Next, the laminated toner image on the recording paper 10 is conveyed to the optical fixing device 90, where it is irradiated with light from the optical fixing device 80, melted, and optically fixed on the recording paper 10 to form a full color image. It is formed.
As described above, the photosensitive member in the image forming apparatus of the present invention is amorphous silicon, and the process speed (peripheral speed of the photosensitive member) is 1000 mm / second or more and 3000 mm / second or less. By using the color toner, it is possible to prevent occurrence of image quality defects and color tone fluctuations based on the cyan toner while maintaining good fixability. The process speed is preferably 1141 mm / second or more and 2800 mm / second or less.

  When the color toner of the present invention is used as, for example, a color toner for light fixing, various uses such as newspapers, service bureaus, barcode printing, label printing, tag printing, Carlson method or ion flow method printers and copying, etc. In particular, since it is possible to provide a product that exhibits good flash fixability at low cost even in the colored embodiment, it is possible to easily meet the demand for colorization of images in these applications. Is.

Hereinafter, the present invention will be specifically described by way of examples.
<Manufacture of toner>
First, each pigment used in the examples is shown in Table 1. In Table 1, “PB” means “CI Pigment Blue”.

  Next, based on the composition shown in Table 2, a toner raw material composed of a binder resin, a charge control agent, an infrared absorber, a wax and a pigment is put into a Henschel mixer and premixed. It knead | mixed by 140-160 degreeC and 250 rpm by the company make, PCM-30). Next, the mixture was coarsely pulverized with a hammer mill, finely pulverized with a jet mill, and then classified with an airflow classifier to obtain toner particles having a volume average particle diameter of about 6.5 μm.

Next, 1.0 part by mass of hydrophobic silica fine particles (TG820F, manufactured by Cabot Corp.) was externally added by a Henschel mixer to 100 parts by mass of each of these toner particles, and the cyan toner (FCTC-) used in each example was used. 10-15) and cyan toners (FCTC-1 to 9, 16-18) used in Comparative Examples were obtained.
The volume resistivity of these toners was measured according to the method described above. These measurement results are shown together in Table 2.

<Production of developer>
A two-component developer was prepared using the obtained toner. As a carrier to be mixed with each toner, a general-purpose ferrite carrier coated with a silicone resin and having a volume average particle size of 30 μm was used. 92 parts of a carrier was mixed with 8 parts of each toner and mixed for 2 hours in a 10 L ball mill to prepare 7 kg of each developer. Using the developer thus obtained, the fixability and color reproducibility were evaluated by the following methods.

<Examples 1-6, Comparative Examples 1-15>
As shown in Table 3, image evaluation including fixability was performed using each developer. As an evaluation apparatus, a DocuPrint 1100CF remodeling machine manufactured by Fuji Xerox Co., Ltd. (schematic configuration is the same as in FIG. 2) equipped with a xenon flash lamp as an optical fixing device was used. FIG. 3 shows the emission waveform of the xenon flash lamp and the absorption intensity with respect to the wavelength of each pigment. The light emission energy of the flash lamp was 3.5 J / cm ² .
The linear speed (process speed) was set to 1150 mm / second except that the comparative examples 13 and 14 were set to 500 mm / second.

(Fixability evaluation)
Plain paper (NIP-1500LT, Kobayashi recording paper) was used as a recording medium, and an image of 1 inch square (2.54 cm × 2.54 cm) was formed by the image forming apparatus. Specifically, cyan toner as shown in Table 3 is used as each color toner for light fixing, and the toner adhesion amount (toner applied amount on the recording medium) is 0.5 mg / cm ^{2 in} a single color. Adjusted and put out the image.

Next, the fixing rate of the obtained 1-inch square image was evaluated as follows. First, the status A density (OD1) corresponding to each color of the image is measured, and then an adhesive tape (Scotch Mending Tape, manufactured by Sumitomo 3M) is applied on the image, and then the adhesive tape is peeled off. The status A density (OD2) of the image was measured. In addition, (X-rite 938) was used for the measurement of optical density. Next, the fixing rate was calculated from the following equation (4) using the obtained optical density value.
Fixing rate (%) = OD2 / OD1 × 100 Formula (4)

The fixing property was evaluated according to the following criteria for the fixing rate calculated from Equation (4).
A: The fixing rate is 90% or more.
A: The fixing rate is 80% or more and less than 90%.
X: The fixing rate is less than 80% (a level that is difficult to use).

(Evaluation of color reproducibility)
The measured values of color reproducibility (L ^* , a ^* , b ^* ) were evaluated for images on which the toners were fixed with the toner adhesion amount of 0.55 to 0.65 mg / cm ² . In addition, each numerical value of the said L ^* , a ^* , b ^* was measured with the spectrometer (938 Spectrodentitometer, X-Rite company). The difference between these measured values and the target color reproducibility value of Japan color was evaluated by the color difference ΔE. The ΔE (color difference) means {(L ₀ ^* −L ₁ ^* ) ² + (a ₀ ^* −a ₁ ^* ) ² + (b ₀ ^* −b ₁ ^* ) ² } ^1/2 . Here, L ₀ ^* , a ₀ ^* , and b ₀ ^* are Japan color color reproducibility target values, and L ₁ ^* , a ₁ ^* , and b ₁ ^* are toner image measurement values.
From these, the color reproducibility was evaluated according to the following criteria.
○: ΔE ≦ 5
Δ: 5 <ΔE ≦ 6
×: 6 <ΔE

(Cover evaluation)
In the white background portion of the image after fixing, the number of fog toners present in the range of 2 mm in diameter was counted with an optical microscope. This measurement was performed at 12 locations on the A2 paper size, and the number of these was averaged and judged according to the following criteria. The printing evaluation environmental conditions were 35 ° C. and 80% RH.
A: The number of fog toners is 30 or less.
A: The number of fog toner is 31 or more and 60 or less.
Δ: The number of fog toner is 61 or more and 100 or less.
X: The number of fog toner is 101 or more.

(Image blur evaluation)
Using a standard chart, output images in A environment (35 ° C, 80% RH) and B environment (21 ° C, 55% RH), and observe the output image with an optical microscope. Judged by the criteria of.
A: Levels A and B are equally good.
○: Image blurring in the A environment is inferior to that in the B environment, but a good level.
Δ: Level of image blur in the A environment that 8 out of 10 panelists do not notice.
X: Level at which 3 or more out of 10 panelists notice image blur in the A environment.
The above evaluation results are summarized in Table 3.

  As shown in Table 3, it can be seen that the color reproducibility, fixability, high-temperature and high-humidity image blur, and high-temperature and high-humidity fog can all be satisfied in the image using the toner combined with the Indanthrone pigment as the pigment of the example. On the other hand, in the case of the toner of the comparative example in which the pigment A and the pigment B are not used together, a problem occurs in any of the above characteristics.

It is a figure which shows the color reproducibility measured value of the toner containing various pigments. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention. It is a graph which shows the light emission waveform of a flash lamp.

Explanation of symbols

1a, 1b, 1c, 1d Charging means 2a, 2b, 2c, 2d Exposure means 3a, 3b, 3c, 3d Photoconductors 4a, 4b, 4c, 4d Developing means 10 Recording paper (recording medium)
20 Cyan developing unit 30 Magenta developing unit 40 Yellow developing unit 50 Black developing units 70a, 70b, 70c, 70d Transfer means 71, 72 Roller 80 Transfer voltage supply means 90 Light fixing means (fixing means)

Claims (2)

A color toner comprising at least a binder resin, a plurality of colorants and an infrared absorber,
The plurality of colorants include at least pigment A and pigment B, and the pigment A is C.I. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: 4, the pigment B is an indanthrone pigment represented by the following structural formula (I), and the mixing ratio of the pigment A and the pigment B contained (mass of pigment B / A color toner, wherein (the sum of the mass of pigment A and the mass of pigment B) is in the range of 0.03 to 0.8.
A latent image carrier, developing means for forming a toner image on the latent image carrier using light fixing color toner, transfer means for transferring the toner image onto a recording medium, and the transferred toner image An image forming apparatus having fixing means for light fixing to a recording medium by light,
The color toner for light fixing includes at least a binder resin, a plurality of colorants, and an infrared absorber, and the plurality of colorants include at least pigment A and pigment B. I. Pigment Blue 15: 1, C.I. I. Pigment Blue 15: 2, C.I. I. Pigment Blue 15: 3 and C.I. I. Pigment Blue 15: is any of the four, the pigment B is indanthrone pigments represented by the following Symbol structural formula (I), the mass mixing ratio (pigment B of pigment A and pigment B contained / (Sum of the mass of pigment A and the mass of pigment B)) is in the range of 0.03 to 0.8, the latent image carrier is amorphous silicon, and the process speed is 1000 mm / second or more and 3000 mm / An image forming apparatus characterized by being less than or equal to seconds.