JP5229045B2 - Image forming apparatus, image forming method, and toner set - Google Patents

Description

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

  In an electrophotographic image forming apparatus, for example, a heat roll method is used as an image fixing method. In this system, a printing material such as paper imaged with toner is passed between heating rolls, and the toner is thermocompression bonded to the printing material.

  On the other hand, as a non-contact fixing method, a method is used in which toner constituting a toner image formed on a transfer target (paper or the like) is fixed on the transfer target by heating and melting. As a fixing device used for this fixing, for example, a flash lamp is arranged opposite to the transfer path of the transfer object, and the flash lamp is turned on intermittently to heat and melt the toner on the transfer object to be transferred. There is technology. The fixing using the flash lamp is characterized by the versatility of the paper and the ease of speeding up due to non-contact, as compared with heat roll fixing.

  Further, with the recent reduction in price and higher output of semiconductor lasers, a fixing system in which a flash lamp is replaced with a high output semiconductor laser has been tried, and is expected as a fixing light source to replace the flash lamp.

  In light fixing methods such as flash fixing and laser fixing, use a toner containing a substance that generates heat from the light source in order to efficiently absorb light in the wavelength region of the light source used for fixing and convert it into thermal energy. Has been proposed (see, for example, Patent Document 1).

JP 2007-248819 A

The object of the present invention is to irradiate the black toner when the light absorption rate at the peak wavelength of light in the infrared region irradiated in the light fixing step exceeds 80%, and in the light fixing step of the color toner. Compared with the case where the light absorption rate at the peak wavelength of light in the infrared region is less than 80% or more than 120% of the light absorption rate at the wavelength of the black toner, the infrared rays using the black toner and the color toner are used. An object of the present invention is to provide an image forming method and an image forming apparatus capable of reducing variations in fixability for each color even when a toner is fixed by irradiating light on a region to form an image of a plurality of colors.
Further, when the light absorption rate of the black toner exceeds 80% at the wavelength of the strongest light absorption peak in the infrared region of the infrared absorber contained in the color toner, and the light of the color toner at the above wavelength. Compared to the case where the absorptance is less than 80% or more than 120% of the light absorptivity at the wavelength of black toner, the toner is fixed by irradiation with light in the infrared region using a black toner and a color toner. It is an object of the present invention to provide a toner set in which the variation in fixing property for each color is reduced even when an image of the above is formed.

The above-mentioned subject is achieved by the following present invention. That is, the invention according to claim 1
An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the image carrier;
A developing step of developing the electrostatic charge image with a black toner for light fixing and a color toner for light fixing to form a black toner image and a color toner image;
A transfer step of transferring the black toner image and the color toner image formed in the development step onto a surface of a transfer target;
A light fixing step of fixing the black toner image and the color toner image transferred to the surface of the transfer object by light exposure in an infrared region;
Have
The black toner is melted by light exposure in the infrared region in the light fixing step, and has a light absorption rate of 30% or more at the peak wavelength of the light in the infrared region irradiated in the light fixing step. % Of black toner,
The color toner contains an infrared absorber, is melted by light exposure in the infrared region in the light fixing step, and is light at a peak wavelength of light in the infrared region irradiated in the light fixing step. In this image forming method, the absorptance is 80% or more and 120% or less with respect to the light absorptance at the wavelength of the black toner.

The invention according to claim 2
An image carrier,
An electrostatic charge image forming apparatus for forming an electrostatic charge image on the surface of the image carrier;
A developing device for developing the electrostatic charge image with a black toner for light fixing and a color toner for light fixing to form a black toner image and a color toner image;
A transfer device for transferring the black toner image and the color toner image formed by the developing device to the surface of a transfer target;
An optical fixing device for fixing the black toner image and the color toner image transferred to the surface of the transfer medium by light exposure in an infrared region;
With
The black toner is melted by the light exposure of the infrared region by the light fixing device, and the light absorption rate at the peak wavelength of the light of the infrared region irradiated by the light fixing device is 30% or more 80 % Of black toner,
The color toner contains an infrared absorber, is melted by light exposure in the infrared region by the light fixing device, and is light at a peak wavelength of light in the infrared region irradiated by the light fixing device. In the image forming apparatus, the absorptance is 80% or more and 120% or less with respect to the light absorptance of the black toner at the wavelength.

The invention according to claim 3
A color toner for photofixing containing an infrared absorber having the strongest light absorption peak in the infrared region, and melted by exposure to light in the infrared region;
A black toner for light fixing that has a light absorption rate at a wavelength of the light absorption peak of 30% or more and 80% or less and melts by light exposure in an infrared region;
Have
In the toner set, the light absorption rate at the wavelength of the light absorption peak of the color toner is 80% or more and 120% or less with respect to the light absorption rate at the wavelength of the black toner.

  According to the first aspect of the invention, the black toner has a light absorption rate at the peak wavelength of light in the infrared region irradiated in the light fixing step of more than 80%, and the color toner has a light fixing step. In comparison with the case where the light absorption rate at the peak wavelength of the light in the infrared region irradiated in the above is less than 80% or more than 120% of the light absorption rate at the wavelength of the black toner, Even when the toner is fixed by irradiation with light in the infrared region to form an image of a plurality of colors, variation in fixability for each color is reduced.

  According to the invention of claim 2, when the light absorption rate at the peak wavelength of light in the infrared region irradiated in the light fixing step of the black toner exceeds 80%, and in the light fixing step of the color toner In comparison with the case where the light absorption rate at the peak wavelength of the light in the infrared region irradiated in the above is less than 80% or more than 120% of the light absorption rate at the wavelength of the black toner, There is provided an image forming apparatus which can reduce variation in fixability for each color even when the toner is fixed by irradiation with light in the infrared region to form an image of a plurality of colors.

  According to the invention of claim 3, when the light absorption rate of the black toner exceeds 80% at the wavelength of the strongest light absorption peak in the infrared region of the infrared absorbent contained in the color toner, and the color Compared to the case where the light absorptance of the toner at the wavelength is less than 80% or more than 120% of the light absorptivity at the wavelength of the black toner, the black toner and the color toner are used. Even when the toner is fixed by irradiation to form an image of a plurality of colors, a toner set is provided in which variation in fixability for each color is reduced.

It is the graph which showed notionally each absorption spectrum of an example of the black toner, and an example of a color toner (yellow toner). 6 is a graph conceptually showing absorption spectra of an example of black toner and an example of color toner (yellow toner) in the toner set according to the first embodiment. The respective absorption spectra of an example of black toner, an example of a primary color toner (yellow toner), and an example of a secondary color toner (yellow toner + magenta toner) in the toner set according to the first embodiment. It is the graph shown conceptually. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. 4 is a graph showing reflection spectra of a black toner, a primary color toner (yellow toner), and a secondary color toner (yellow toner + magenta toner) in Example 1. FIG. 7 is a graph showing reflection spectra of a black toner, a primary color toner (yellow toner), and a secondary color toner (yellow toner + magenta toner) in Example 2. 6 is a graph showing reflection spectra of a black toner, a primary color toner (yellow toner), and a secondary color toner color (yellow toner + magenta toner) in Comparative Example 1;

  Hereinafter, embodiments of the present invention will be described in detail.

<First Embodiment / Light Fixing Toner Set>
The photofixing toner set according to the first embodiment (hereinafter, the photofixing toner set is simply referred to as “toner set”) contains an infrared absorber having the strongest light absorption peak in the infrared region, and includes infrared. A light fixing color toner (hereinafter referred to simply as “color toner”) that melts upon exposure to light in a region, and a light absorption rate at a wavelength of the light absorption peak of 30% to 80% %, And a black toner for light fixing that melts by light exposure in the infrared region (hereinafter, the black toner for light fixing is simply referred to as “black toner”). The light absorption rate at the wavelength of the light absorption peak is 80% or more and 120% or less with respect to the light absorption rate at the wavelength of the black toner.

  The black toner and the color toner in the toner set according to the first embodiment are used as toners for developing the electrostatic latent image and forming a toner image in the image forming method and the image forming apparatus. Further, it is a toner that is melted and fixed on the surface of the transfer medium using the light energy when the light in the infrared region is exposed (that is, the toner is fixed on the surface of the transfer medium by the light fixing method).

Conventionally, in a photo-fixing type image forming method and an image forming apparatus for forming an image of a plurality of colors using black toner and color toner, one type of light source used for fixing black toner and one used for fixing color toner is used. In the embodiment performed with only the light source, the following phenomenon occurred.
(1) If the light source is set so as to irradiate with sufficient irradiation energy for fixing the color toner, the irradiation energy becomes too large for the black toner, and voids (white spots in the image) are caused by overheating of the black toner. Generation and gas generation will occur.
(2) If the light source is set so that the irradiation energy does not occur when black toner is fixed, the fixing property of the color toner is deteriorated.
(3) When the concentration of the infrared absorber is increased in order to improve the light absorption rate in the infrared region of the color toner to the same level as that of the black toner, the light absorption in the visible region by the infrared absorber also increases. As a result, the color toner The color tone is deteriorated, and the cost is increased because a large amount of infrared absorber is used.

Here, FIG. 1 shows a graph conceptually showing respective absorption spectra of an example of a conventional black toner and an example of a color toner (yellow toner).
In particular, the conventional black toner uses a pigment that absorbs the visible region and the infrared region to the maximum, such as carbon black, for the purpose of producing a black color and using the irradiation light from the light source as effectively as possible. . Therefore, as shown in FIG. 1, in order to fix the color toner to be used at the same level as that of the black toner, a large amount of infrared absorber is added, and the infrared region (that is, the wavelength region of the irradiated light) is added. It is necessary to make the light absorption rate the same level as that of the black toner, and as a result, there is a concern about the deterioration of the color and the cost increase.

  Furthermore, when a secondary color (for example, yellow-Y + magenta M, magenta M + cyan C, cyan C + yellow Y, etc.) is fixed using a plurality of color toners, the secondary color is affected by an increase in toner amount. The required irradiation energy is greater than the primary color. Therefore, if the irradiation intensity is set to fix the secondary color, the primary color toner or black toner may be heated excessively, resulting in the generation of voids (white spots in the image) and the generation of gas. It was.

  On the other hand, in the toner set according to the first embodiment, the black toner can be achieved by the idea of intentionally reducing the light absorption rate necessary for fixing.

Here, FIG. 2 is a graph conceptually showing an absorption spectrum of an example of the black toner and the color toner (yellow toner) in the toner set according to the first embodiment.
The light absorptance of the black toner shown in FIG. 2 at the wavelength of light irradiated during fixing is adjusted to 50%. Therefore, as shown in FIG. 2, the amount of the infrared absorbent added to reduce the light absorption rate of the combined color toner to the same level as that of the black toner is reduced. As a result, the color depending on the infrared absorbent is reduced. Suppression of taste deterioration and cost reduction are realized.

In addition, from the viewpoint of making the fixing property of the black toner and the color toner in the toner set according to the first embodiment the same level, the wavelength of the strongest light absorption peak in the infrared region of the infrared absorbent contained in the color toner. The light absorption rate of the color toner is adjusted to 80% to 120% with respect to the light absorption rate at the wavelength of the black toner.
When the light absorption rate of the color toner and the light absorption rate of the black toner satisfy the above relationship, when the color secondary color is fixed by the color toner, the light absorption rate of the light irradiated from the color primary color Increases, and an increase in necessary irradiation energy is suppressed. For this reason, even at the irradiation intensity for fixing the secondary color, excessive heating of the primary color toner and black toner is suppressed, and as a result, generation of voids (white spots in the image) and generation of gas are suppressed. It is also expected.

Here, FIG. 3 shows an example of the black toner in the toner set according to the first embodiment, an example of the primary color (yellow toner) of the color toner in the toner set, and the secondary color of the color toner (yellow toner + magenta). The graph which showed notionally each absorption spectrum with an example of (toner) is shown.
The light absorptance of the black toner and the yellow toner shown in FIG. 3 at the wavelength of light irradiated at the time of fixing is adjusted to 50%. Therefore, as shown in FIG. 3, the light absorption rate when fixing a secondary color (yellow toner + magenta toner) is increased, and as a result, an increase in necessary irradiation energy is suppressed.

  In the present specification, “infrared light” refers to light having a wavelength of 770 nm to 1000 nm.

In this specification, “black toner” refers to a toner having the weakest light absorption rate of 80% or more in the visible region (region having a wavelength of 400 nm to 700 nm).
On the other hand, “color toner” refers to toner other than the black toner that reflects light of an arbitrary wavelength in the visible region.

  In the present specification, “infrared absorber” refers to an additive having the strongest light absorption peak in the infrared region.

  Further, in the present specification, the “set” of the toner set means a combination of toners mounted in combination in one multicolor image forming apparatus, and the toner set according to the present embodiment is a single multicolor image. By mounting and using in combination with the forming apparatus, the above-described object can be achieved. Therefore, the “set” does not necessarily mean that one or more kinds of black toner and one or more kinds of color toners are combined and distributed and sold as a product.

-Light absorption rate-
The black toner in the toner set according to the first embodiment has a light absorption rate of 30% or more and 80% or less at the wavelength of the strongest light absorption peak in the infrared region of the infrared absorbent contained in the color toner. If it is less than 30%, the fixing property of the black toner deteriorates. On the other hand, if it exceeds 80%, the deterioration of the color tone is not suppressed when a multi-color image is formed using the black toner and the color toner. In addition, the cost increases.
The light absorptance is preferably 35% or more and 70% or less, and particularly preferably 40% or more and 60% or less.

Here, the light absorptance of the black toner at the above wavelength is calculated by measuring the reflection spectrum. The reflection spectrum is measured with a spectrophotometer U-4100 manufactured by Hitachi, Ltd.
However, in this specification, the “light absorption rate” is the light absorption rate after fixing each toner on the surface of the transfer target. That is, after printing black for black toner, yellow for yellow toner, magenta for magenta toner, and cyan for cyan toner, the wavelength that shows the strongest light absorption peak in the infrared region is printed. Is the light absorption rate.

  Furthermore, it is more preferable that the light absorptance at the wavelength of light irradiated at the time of fixing is 30% or more and 80% or less. Further, the light absorption rate is preferably 35% or more and 70% or less, and particularly preferably 40% or more and 60% or less.

-Ratio of light absorption rate between black toner and color toner-
The color toner in the toner set according to the first embodiment has a light absorptance at the wavelength of the strongest light absorption peak in the infrared region of the infrared absorbent contained in the color toner, and the light at that wavelength of the black toner. It is 80% or more and 120% or less (light absorption rate ratio) with respect to the absorption rate. By satisfying the above range, as compared with the case where this configuration is not provided, variation in fixability with the black toner is suppressed, and further, the fixing energy of the secondary color is also reduced.
In addition, it is more preferable that the ratio of the light absorption rate to the black toner light absorption rate is closer to 100%.

  Here, the light absorptance of the color toner at the above wavelength is calculated by measuring the reflection spectrum. The reflection spectrum is measured by the method described above.

  Furthermore, it is more preferable that the light absorption rate of the color toner at the wavelength of light irradiated during fixing is 80% or more and 120% or less with respect to the light absorption rate at the wavelength of the black toner. The light absorptance ratio is preferably closer to 100%.

(Black toner composition)
The aforementioned black toner having a light absorption rate at a wavelength of the strongest light absorption peak in the infrared region of the infrared absorbent contained in the color toner of 30% or more and 80% or less is not particularly limited. For example, it is prepared by the following composition.
(1) A black toner containing a yellow pigment, a magenta pigment, and a cyan pigment (2) A black pigment having an optical absorptance of 80% or less at the above wavelength (hereinafter referred to as “non-infrared absorbing black pigment”) Black toner containing

  In addition, in order to adjust the light absorptance in an infrared region, you may contain at least 1 type further selected from carbon black and an infrared absorber. In addition, it can be realized by a combination of complementary colors such as a red pigment + cyan pigment, a green pigment + magenta pigment, and a blue pigment + yellow pigment.

(1) Black toner containing a yellow pigment, a magenta pigment, and a cyan pigment A black toner is obtained by mixing a yellow pigment, a magenta pigment, and a cyan pigment to obtain a black toner and exhibiting a good light absorption rate in the visible region. And a black toner having a reduced light absorptance in the infrared region. In addition, when adjusting the light absorptance in an infrared region, at least 1 type selected from carbon black and an infrared absorber is contained further.

-Colorant-
A known colorant is used for the black toner.
Examples of the cyan pigment include C.I. I. Pigment Blue 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 13, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17, 17, 23, 60, 65, 73, 83, 180, C.I. I. Examples include cyan cyan pigments such as Vatcyan 1, 3 and 20, etc., bitumen, cobalt blue, alkali blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, first sky blue and indanthrene blue BC. .
In addition, C.I. I. Cyan dyes such as solvent cyan 79 and 162 are also used. Among these, C.I. I. Pigment Blue 15: 3 is effective.

Examples of magenta pigments include 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, 50, 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, and the like, and pigment violet 19 magenta pigments.
In addition, 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., bengara, cadmium red, red lead, mercury sulfide, permanent red 4R, risor 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 are also used.

  Examples of yellow pigments include C.I. I. Pigment Yellow 2, 3, 15, 15, 16, 17, 97, 180, 185, 139, and the like.

  The amount of each colorant added is preferably in the range of 5 parts by mass or more and 30 parts by mass or less in 100 parts by mass of the toner prepared by mixing with a binder resin described later.

-Infrared absorber-
Examples of the contained infrared absorber include squarylium dyes, croconium dyes, naphthalocyanine dyes, cyanine dyes, aminium dyes, and the like.

  In addition, when the infrared absorber is added to the black toner of the above (1), the total amount is desirably in the range of 0.01 parts by mass to 3 parts by mass with respect to 100 parts by mass of the toner.

-Carbon black-
Examples of carbon black contained are # 30, # 40, # 44, # 45, # 45L, # 900, # 960, # 970, MA7, MA8, MA11, MA77, MA100, MA230 (manufactured by Mitsubishi Chemical). Color Black S160, S170, FW200, Special Black4A, Printex60, 75, L, Nipex60, 150, 180IQ (manufactured by Degussa), Regal660R, Monarch800, 880, 1000, 1100, 1300 1400 (made by Cabot).

  The addition amount when carbon black is added to the black toner of (1) is preferably in the range of 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner.

  The other composition in the black toner (1) will be described later.

(2) Black toner containing non-infrared absorbing black pigment A black pigment having a light absorption rate of 80% or less at the wavelength of the strongest light absorption peak in the infrared region of the infrared absorbent contained in the color toner is used. By obtaining a black toner, a black toner having a good light absorptance in the visible region and excellent blackness, and having a reduced light absorptance in the infrared region can be obtained. In addition, when adjusting the light absorptance in an infrared region, at least 1 type selected from carbon black and an infrared absorber is contained further.
In addition, the light absorption rate at the above wavelength is more preferably 70% or less, and particularly preferably 60% or less.

  Further, the non-infrared absorbing black pigment preferably has a light absorption rate of 80% or less, more preferably 70% or less, and more preferably 60% or less at the wavelength of light irradiated at the time of fixing. It is particularly preferred that

-Non-infrared absorbing black pigment-
Examples of non-infrared absorbing black pigments include Pigment Black 1, Pigment Black 20, Pigment Black 31, Pigment Black 32, and “coloring material” having a squarylium skeleton described in JP-A-2008-184606.

  The addition amount of the non-infrared absorbing black pigment is preferably in the range of 2 parts by mass or more and 30 parts by mass or less in 100 parts by mass of the toner prepared by mixing with a binder resin described later.

-Infrared absorber-
As the infrared absorber contained, for example, those listed in the description of the black toner in (1) above are used.
In addition, when the infrared absorber is added to the black toner of the above (2), the total amount is desirably in the range of 0.05 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner.

-Carbon black-
As the carbon black contained, for example, those listed in the description of the black toner in (1) above are used.
The addition amount when carbon black is added to the black toner of (2) is preferably in the range of 0.01 to 3 parts by mass with respect to 100 parts by mass of the toner.

  Next, other compositions used for the black toner (1) and the black toner (2) will be described.

-Binder resin-
A known binder resin is used for the black toner. The main component of the binder resin is preferably polyester or polyolefin, but a copolymer of styrene and acrylic acid or methacrylic acid, a copolymer of styrene and acrylic acid ester or methacrylic acid ester, 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 Etc. can be used alone or in combination. Among these, it is preferable to use a polyester-based resin or a norbornene polyolefin resin.
The Tg (glass transition temperature) of the binder resin used for the toner is preferably in the range of 50 ° C. or higher and 70 ° C. or lower.

-Other additives-
In addition, a charge control agent or wax may be added to the black toner as necessary.
As the charge control agent, known calixarene, nigrosine dye, quaternary ammonium salt, amino group-containing polymer, metal-containing azo dye, salicylic acid complex compound, phenol compound, azochrome, azozinc, etc. are used. . In addition, magnetic materials such as iron powder, magnetite, and ferrite can be mixed in the toner, and the toner can also be used. In particular, in the case of black toner, white magnetic powder may be used.

  As the wax, ester wax, polyethylene, polypropylene, or a copolymer of polyethylene and polypropylene is most preferable. , Unsaturated fatty acids such as palmitic acid, stearic acid, montanic acid, brandic acid, eleostearic acid, valinalic acid, stearic alcohol, aralkyl alcohol, behenyl alcohol, carnauvir alcohol, ceryl alcohol, melyl alcohol, or even longer Saturated alcohols such as long-chain alkyl alcohols having a chain alkyl group; polyhydric alcohols such as sorbitol; linoleic acid amide, olein Fatty acid amides such as amide and lauric acid amide; saturated fatty acid bisamides such as methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide and hexamethylene bisstearic acid amide, ethylene bisoleic acid amide and hexamethylene Unsaturated fatty acid amides such as bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sebacic acid amide; m-xylene bisstearic acid amide, N, N′-distearyl Aromatic bisamides such as isophthalic acid amides; Fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate and magnesium stearate (generally called metal soaps); aliphatic hydrocarbon waxes with styrene and Waxes grafted with vinyl monomers such as formic acid; Partial esterified products of fatty acids such as behenic acid monoglyceride and polyhydric alcohols; Methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils, etc. Is mentioned.

  As the wax, a wax material that exhibits an endothermic peak by DSC measurement (differential scanning calorimetry) at 50 ° C. or more and 90 ° C. or less is preferable. 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.

-Black toner production method-
In producing the black toner, a commonly used kneading and pulverizing method or wet granulation method is used. Here, as the wet granulation method, suspension polymerization method, emulsion polymerization method, emulsion polymerization aggregation method, soap-free emulsion polymerization method, non-aqueous dispersion polymerization method, in-situ polymerization method, interfacial polymerization method, emulsion dispersion granulation Laws are used.

  In order to produce the black toner by the kneading and pulverization method, a binder resin, an infrared absorber, a wax, a charge control agent, a pigment or dye as a colorant, and other additives are mixed with a Henschel mixer, a ball mill, or the like. Mix thoroughly with a machine, melt and knead using a heat kneader such as a heating roll, kneader, extruder, etc. to make the resins compatible with each other, infrared absorbers, antioxidants, pigments, dyes, magnetic materials, etc. Is dispersed or dissolved, cooled and solidified, and pulverized and classified to obtain a toner. Moreover, in order to improve the dispersibility of a pigment or an infrared absorber, you may perform a masterbatch.

  Further, when adding the infrared absorbent to the toner, the infrared absorbent may be adhered or fixed to the surface of the toner particles in addition to dispersing the infrared absorbent in the black toner as described above.

-Physical properties of black toner-
The black toner produced as described above preferably has a volume average particle diameter D50v of 3 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.
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 or more and 1.25 or less.

On the other hand, when toner particles are produced by the wet granulation method, the shape factor SF1 of the toner particles is preferably in the range of 110 to 135.
The toner shape factor SF1 is obtained by taking toner particles dispersed on a slide glass or an optical microscope image of the toner into a Luzex image analyzer through a video camera, and obtaining the maximum length and projected area of 50 or more toners. It is obtained by calculating by (1) and obtaining the average value.
SF1 = (ML ² / A) × (π / 4) × 100 (1)
In the above formula (1), ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.

The volume particle size distribution index GSDv of the toner particles is preferably 1.25 or less.
The toner volume average particle size, the particle size distribution index, and the like were measured using a Coulter Counter TAII (manufactured by Beckman-Coulter) and the electrolyte using ISOTON-II (manufactured by Beckman-Coulter).

  For the divided particle size range (channel), the measured particle size distribution is drawn from the smaller diameter side for each volume and number, and the particle size at which accumulation is 16% is the volume average particle size D16v and number average particle size. D16p is defined, and the particle size at 50% cumulative is defined as a volume average particle size D50v (the volume average particle size of the toner described above indicates this) and a number average particle size D50p. In addition, the particle diameters that are 84% cumulative are defined as volume average particle diameter D84v and number average particle diameter D84p. Using these, the volume average particle size distribution index (GSDv) is calculated as D84v / D16v.

-External additive-
The black toner may be used by mixing toner particles with white inorganic particles. 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 the inorganic powder include silica powder, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, and chromium oxide. Cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride and the like, and silica powder is particularly preferable. Moreover, well-known materials, such as a silica, titanium, resin 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 particle powder of a fluorine-based high molecular weight substance may be added.
The black toner can be obtained by sufficiently mixing the inorganic particles and desired additives with a mixer such as a Henschel mixer.

(Color toner composition)
Next, preferable composition components of the color toner in the toner set according to the first embodiment will be described.

The color toner contains a colorant and a binder resin, and may further contain an infrared absorber, a charge control agent, a wax and the like.
As the colorant used in the color toner, the colorants listed in the above-mentioned “(1) Black toner containing yellow pigment, magenta pigment and cyan pigment” are preferably used as they are.

As for “infrared absorber, charge control agent, wax”, those already enumerated in the description of the black toner are preferably used as they are. Furthermore, you may contain the additive enumerated as another additive in description of a black toner.
The light absorption rate in the infrared region of the color toner is adjusted by adjusting the type and amount of the infrared absorber.

(Career)
The black toner and the color toner in the toner set according to the first embodiment may be mixed with a carrier and used as a two-component developer. Examples of the carrier 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 are used. The carrier coating agent is not particularly limited, but a silicone resin system is particularly desirable.

<Second Embodiment / Image Forming Method, Third Embodiment / Image Forming Apparatus>
The image forming method according to the second embodiment includes an electrostatic charge image forming step of forming an electrostatic charge image on the surface of an image carrier, and the electrostatic charge image is formed by a black toner for light fixing and a color toner for light fixing. A developing step of developing and forming a black toner image and a color toner image; a transferring step of transferring the black toner image and the color toner image formed in the developing step onto the surface of the transfer member; A light fixing step of fixing the transferred black toner image and the color toner image by exposure to light in an infrared region, wherein the black toner is used for light in the infrared region in the light fixing step. A black toner having a light absorption rate at a peak wavelength of light in the infrared region which is melted by exposure and irradiated in the light fixing step, and is 30% or more and 80% or less, and the color toner A light absorption rate at a peak wavelength of light in the infrared region, which contains an infrared absorber, is melted by light exposure in the infrared region in the light fixing step, and is irradiated in the light fixing step. The black toner has a light absorption rate at the wavelength of 80% or more and 120% or less.

  In addition, an image forming apparatus according to the third embodiment includes an image carrier, an electrostatic image forming device that forms an electrostatic image on the surface of the image carrier, and the electrostatic image as a black toner for photofixing. And a developing device for developing a black toner image and a color toner image by developing with a color toner for light fixing, and a transfer device for transferring the black toner image and the color toner image formed by the developing device to the surface of a transfer medium And a light fixing device that fixes the black toner image and the color toner image transferred to the surface of the transfer medium by exposure to light in an infrared region, and the black toner is produced by the light fixing device. Black toner that is melted by exposure to light in the infrared region and has a light absorption rate of 30% to 80% at the peak wavelength of the light in the infrared region irradiated by the light fixing device The color toner contains an infrared absorber, is melted by light exposure in the infrared region by the light fixing device, and has a peak wavelength of light in the infrared region irradiated by the light fixing device; The light absorption rate of the black toner is 80% or more and 120% or less with respect to the light absorption rate at the wavelength of the black toner.

-Light absorption rate-
The black toner in the image forming method according to the second embodiment and the image forming apparatus according to the third embodiment has a light absorption rate of 30% or more at the peak wavelength of light in the infrared region irradiated by the light fixing device. 80% or less. If it is less than 30%, the fixing property of the black toner deteriorates. On the other hand, if it exceeds 80%, the deterioration of the color tone is not suppressed when a multi-color image is formed using the black toner and the color toner. In addition, the cost increases.
The light absorptance is preferably 35% or more and 70% or less, and particularly preferably 40% or more and 60% or less.

  Here, the light absorptance of the black toner at the above wavelength is calculated by measuring the reflection spectrum. The reflection spectrum is measured with a spectrophotometer U-4100 manufactured by Hitachi, Ltd.

-Ratio of light absorption rate between black toner and color toner-
The color toner in the image forming method according to the second embodiment and the image forming apparatus according to the third embodiment has a light absorptance at the peak wavelength of light in the infrared region irradiated by the light fixing device. It is 80% or more and 120% or less (light absorption rate ratio) with respect to the light absorption rate at the wavelength. By satisfying the above range, as compared with the case where this configuration is not provided, variation in fixability with the black toner is suppressed, and further, the fixing energy of the secondary color is also reduced.
In addition, it is more preferable that the ratio of the light absorption rate to the black toner light absorption rate is closer to 100%.

  Here, the light absorptance of the color toner at the above wavelength is calculated by measuring the reflection spectrum. The reflection spectrum is measured by the method described above.

-Light source-
Examples of the light source (fixing means) used in the image forming method according to the second embodiment and the optical fixing device of the image forming apparatus according to the third embodiment include a normal halogen lamp, mercury lamp, flash lamp, and infrared laser. However, in particular, an infrared laser is preferable from the viewpoint of monochromaticity of the light source and output. Examples of the infrared laser include a light source exhibiting high directivity in the infrared region, such as a semiconductor laser, a dye laser, a titanium sapphire laser, and an OPO laser. The emission energy of the light source is preferably 0.1 J / cm ² or more 7.0J / cm ² or less in the range, further, at 0.3 J / cm ² or more 6.0 J / cm ² or less in the range It is more preferable.

Hereinafter, an example of the image forming apparatus will be described with reference to the drawings. FIG. 4 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the third embodiment to which the image forming method according to the second embodiment is applied.
The image forming apparatus 10 shown in FIG. 4 feeds the recording medium P wound in a roll shape by the paper feed roller 28, and the feeding direction of the recording medium P on one side of the recording medium P fed in this way. Four image forming units 12 (black (K), yellow (Y), magenta (M), cyan (C)) are provided in parallel from the upstream side to the downstream side, and the image forming unit 12 is further provided. A light fixing type fixing device 26 is provided on the downstream side.

  The black image forming unit 12K is a known electrophotographic image forming unit. Specifically, a charger 16K, an exposure unit 18K, a developing unit 20K, and a cleaner 22K are provided around the photoconductor 14K, and a transfer unit 24K is provided via the recording medium P. The other yellow, magenta, and cyan image forming units 12Y, M, and C are also as described above.

  Here, as the photoconductor 14 (K, Y, M, C), generally, an inorganic photoconductor using an inorganic photoconductive material such as amorphous silicon or selenium, or an organic photoconductive material such as phthalocyanine is used. An organic photoreceptor is used.

  In the image forming apparatus 10 shown in FIG. 4, toner images are sequentially transferred by a known electrophotographic method by the image forming units 12 </ b> K, Y, M, and C onto the recording medium P drawn out from the roll state. The toner image is light-fixed by the fixing device 26 to form an image.

  Note that the developing devices 12Y, 12M, 12C, and 12K shown in FIG. 4 are connected to toner cartridges corresponding to the developing devices (colors) by a developer supply pipe (not shown). Further, when the amount of toner stored in the toner cartridge is low, this toner cartridge may be replaced.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited by the following Example.

[Example 1]
-Production of infrared absorber A-
Infrared absorbent A (squarylium dye) shown below was produced by the following method.
1,8-diaminonaphthalene 4.843 g (purity: 98%, 30 mmol), 3,5-dimethylcyclohexanone 3.863 g (purity: 98%, 30 mmol), p-toluenesulfonic acid monohydrate 10 mg (0.05 mmol) ), And 45 ml of toluene were heated with stirring in a nitrogen gas atmosphere and refluxed at 110 ° C. for 10 hours. Water generated during the reaction was removed by azeotropic distillation. After completion of the reaction, toluene was distilled off, and the dark brown solid obtained was extracted with acetone, purified by recrystallization from a mixed solvent of acetone and ethanol, and dried to yield 4.955 g of intermediate (yield 62%).

  A mixture of 913 mg of 3,4-dihydroxycyclobut-3-ene-1,2-dione, 8.0 ml of n-butanol and 60 ml of toluene was added to 4.955 g of the above intermediate, and nitrogen gas was added. The mixture was heated with stirring in an atmosphere and refluxed at 105 ° C. for 3 hours. Water generated during the reaction was removed by azeotropic distillation. After completion of the reaction, most of the solvent was distilled off in an atmosphere of nitrogen gas, and 120 ml of hexane was added while stirring the resulting reaction mixture. The resulting black brown precipitate was filtered by suction, washed with hexane, and dried to obtain a black blue solid. This solid was washed successively with ethanol, acetone, a 60 mass% aqueous ethanol solution, ethanol and acetone, and 4.30 g of the desired infrared absorber A (perimidine-based squarylium compound (I)) represented by the following formula (I) ( Yield 88%).

-Preparation of black toner-
0.1 part by mass of the infrared absorber A, 95 parts by mass of polyester resin: bisphenol-propylene oxide adduct / fumaric acid condensate (manufactured by Kao Corporation), yellow pigment: C.I. I. Pigment Yellow 180, 10 parts by mass, magenta pigment: C.I. I. Pigment Red 122 (6 parts by mass), cyan pigment: C.I. I. 5 parts by weight of Pigment Blue 15: 3, 1 part by weight of a charge control agent (CCA100, manufactured by Chuo Synthetic Chemical), and 0.5 parts by weight of wax: NP105 (Mitsui Chemicals) were prepared as toner components. The entire amount of the toner component was put into a Henschel mixer, premixed, and melt-kneaded with an extruder. Next, the obtained mixture was cooled and solidified, then coarsely pulverized with a hammer mill, and further finely pulverized with a jet mill. The obtained fine powder was classified with an airflow classifier to obtain black colored particles (toner particles) having a volume average particle size of 8.5 μm. Subsequently, 0.5 part by mass of hydrophobic silica particles (trade name: H3004, manufactured by Clariant Japan Co., Ltd.) was added to the obtained toner particles, and external addition processing was performed using a Henschel mixer.

  Further, it was mixed with a silicone resin coated carrier (particle size 50 μm) to prepare a black developer.

-Preparation of color toner (yellow)-
0.1 part by mass of the infrared absorber A, 95 parts by mass of a polyester resin (used in the black toner), pigment: C.I. I. 10 parts by weight of Pigment Yellow 180, 1 part by weight of a charge control agent (CCA100, manufactured by Chuo Synthetic Chemical), and 0.5 parts by weight of wax: NP105 (Mitsui Chemicals) were prepared as toner components. The entire amount of the toner component was put into a Henschel mixer, premixed, and melt-kneaded with an extruder. Next, the obtained mixture was cooled and solidified, then coarsely pulverized with a hammer mill, and further finely pulverized with a jet mill. The obtained fine powder was classified with an airflow classifier to obtain yellow colored particles (toner particles) having a volume average particle size of 8.5 μm. Subsequently, 0.5 part by mass of hydrophobic silica particles (trade name: H3004, manufactured by Clariant Japan Co., Ltd.) was added to the obtained toner particles, and external addition processing was performed using a Henschel mixer.

  Further, it was mixed with a silicone resin coated carrier (particle size 50 μm) to produce a yellow developer.

-Preparation of color toner (magenta)-
0.1 part by mass of the infrared absorber A, 95 parts by mass of a polyester resin (used in the black toner), pigment: C.I. I. 6 parts by weight of Pigment Red 122 (manufactured by Dainichi Seika), 1 part by weight of charge control agent (CCA100, manufactured by Chuo Synthetic Chemical), and 0.5 parts by weight of wax: NP105 (Mitsui Chemicals) were prepared as toner components. . The entire amount of the toner component was put into a Henschel mixer, premixed, and melt-kneaded with an extruder. Next, the obtained mixture was cooled and solidified, then coarsely pulverized with a hammer mill, and further finely pulverized with a jet mill. The obtained fine powder was classified with an airflow classifier to obtain magenta colored particles (toner particles) having a volume average particle diameter of 8.5 μm. Subsequently, 0.5 part by mass of hydrophobic silica particles (trade name: H3004, manufactured by Clariant Japan Co., Ltd.) was added to the obtained toner particles, and external addition processing was performed using a Henschel mixer.

  Further, it was mixed with a silicone resin coated carrier (particle size 50 μm) to prepare a magenta developer.

[Evaluation]
(1) Reflection spectrum measurement About the color toner obtained from the above, the reflection spectrum was measured by the spectrophotometer U-4100 made from Hitachi, Ltd. However, as described above, the measurement was performed after fixing the toner on the surface of the transfer target. That is, the measurement was performed after the yellow color was printed with the yellow toner.
Specifically, first, an image forming apparatus (manufactured by Fuji Xerox Co., Ltd., trade name: Docu Center Color 2220) is used as a light source in the light fixing device, manufactured by COHERENT, trade name: HighLight ISL-2000L (exposure wavelength: 808 nm). And a fixed image was obtained on the paper using the yellow toner. Subsequently, the reflection spectrum was measured with the spectrophotometer.
Further, the reflection spectrum of the black toner was also measured.
Further, a secondary color image was printed using the yellow toner and the magenta toner, and the reflection spectrum was also measured.
The results are shown in FIG.

  Further, the light absorption rate of the black toner and the light of the yellow toner in the “wavelength: 808 nm (the wavelength of light exposed during fixing in the fixability evaluation test described in (2) below)” measured by the reflection spectrum described above. Table 2 shows the absorption ratio and the ratio of the light absorption ratio of the yellow toner to the light absorption ratio of the black toner (light absorption ratio).

(2) Fixability evaluation (crease evaluation)
Further, the fixability of the toner was measured by the following crease evaluation. The crease evaluation is one of evaluation indexes for fixing image foldability and image fixability.

First, using an image forming apparatus (trade name: Docu Center Color 2220, manufactured by Fuji Xerox Co., Ltd.), a COHERENT product name, HighLight ISL-2000L (exposure wavelength: 808 nm) is mounted as a light source in the light fixing device. The irradiation energy was set to 1.5 J / cm ² and a fixed image was obtained on paper using the color developer (yellow). Next, the paper on which the fixed image was formed was bent once, the opened and folded image portion was wiped with cotton, and the degree of image peeling was expressed by a numerical value. Specifically, a 20 mm diameter image with a color toner layer is folded once, opened and lightly wiped with cotton, and the white width of the image width expressed in units of μm is used as an index. The following are acceptable ranges.
The lower the value, the better the fixability.
Further, crease evaluation was performed on the black developer, and further, a secondary color image was formed using the yellow toner and magenta toner, and crease evaluation was also performed on this.

The fixability was determined from the crease evaluation values according to the following criteria. The results are shown in Table 2.
○: Crease value of 40 or less ×: Crease value exceeding 40

(3) Color difference ΔE
First, in the method described in (2) above, the irradiation energy was set to 1.5 J / cm ² , and a fixed image with a color developer (yellow) was formed on a sheet.
Next, a developer is prepared using the toner obtained by removing the infrared absorber from the color toner (yellow), and in the method described in (2) above, the toner is transferred instead of being fixed by an optical fixing device. The obtained paper was sandwiched between Teflon (registered trademark) sheets, and passed through a pouch laminator (manufactured by Nippon GC Co., Ltd., GLM 2500, speed setting 1, temperature setting 120 ° C.) to obtain a fixed image.

Using a reflection spectral densitometer (x-rite 939, manufactured by X-Rite Co., Ltd.), the color of the fixed image of the color toner containing the infrared absorber and the fixed image of the color toner not containing the infrared absorber is evaluated, and L * , A *, b * were measured (that is, L ₁ , a ₁ , b ₁ , L ₂ , a ₂ and b ₂ in the following formula (2) were measured), and the color difference ΔE was calculated. The results are shown in Table 1.
Here, ΔE is called a color difference in the CIE 1976 L * a * b * color system, and indicates that the larger the ΔE, the different the apparent colors of the two colors to be compared.
Equation _{(2) ΔE = {(L} 1 -L 2) 2 + (a 1 -a 2) 2 + (b 1 -b 2) 2} 1/2
(In the formula (2), L ₂ , a ₂ and b ₂ represent the L value, a value and b value in the fixed image of the color toner for light fixing, and L ₁ , a ₁ and b ₁ represent the light (The L value, a value, and b value in the fixed image of the color toner excluding the infrared absorber in the fixing color toner are shown.)

(4) Generation of voids and generation of gas When an image of color toner (yellow), an image of black toner, and a secondary color image of yellow toner and magenta toner are formed by the method described in (2) above. The presence or absence of "gas generation" and the presence or absence of "void generation in black toner" were visually confirmed and evaluated according to the following evaluation criteria. The results are shown in Table 2.
-Generation of voids-
○: Generation of voids was not confirmed visually. ×: Generation of voids was confirmed visually. -Gas generation-
○: Gas generation was not confirmed visually. ×: Gas generation was confirmed visually.

[Example 2]
-Preparation of black toner-
0.1 parts by mass of the infrared absorber A, 95 parts by mass of polyester resin (used in the black toner of Example 1), 6 parts by mass of squarylium ST345 described in JP-A-2008-184606, charge control 1 part by weight of an agent (CCA100, manufactured by Chuo Synthetic Chemical) and 0.5 part by weight of wax: NP105 (Mitsui Chemicals) were prepared as toner components. The entire amount of the toner component was put into a Henschel mixer, premixed, and melt-kneaded with an extruder. Next, the obtained mixture was cooled and solidified, then coarsely pulverized with a hammer mill, and further finely pulverized with a jet mill. The obtained fine powder was classified with an airflow classifier to obtain black colored particles (toner particles) having a volume average particle size of 8.5 μm. Subsequently, 0.5 part by mass of hydrophobic silica particles (trade name: H3004, manufactured by Clariant Japan Co., Ltd.) was added to the obtained toner particles, and external addition processing was performed using a Henschel mixer.

  Further, it was mixed with a silicone resin coated carrier (particle size 50 μm) to prepare a black developer.

-Preparation of color toner (yellow)-
A yellow color toner and a yellow developer were prepared by the method described in “Production of Color Toner (Yellow)” in Example 1.

-Preparation of color toner (magenta)-
A magenta color toner and a magenta developer were prepared by the method described in “Production of Color Toner (Magenta)” in Example 1.

The method described in Example 1 was evaluated using the developer.
FIG. 6 shows the result of the reflection spectrum measurement, and Table 1 shows the result of the color evaluation in measuring the color difference ΔE. The light absorption rate of the black toner, the light absorption rate of the yellow toner, and the light absorption rate of the yellow toner are described above. Table 2 shows the ratio of the black toner to the light absorption rate (light absorption rate ratio), crease evaluation, ΔE, gas generation, and void generation evaluation results.

[Comparative Example 1]
-Preparation of black toner-
95 parts by mass of a polyester resin (used in the black toner of Example 1), 10 parts by mass of black pigment: Nipex 35 (manufactured by Cabot), 1 part by mass of a charge control agent (CCA100, manufactured by Chuo Synthetic Chemical), wax : NP105 (Mitsui Chemicals) 0.5 parts by mass was prepared as a toner component. The entire amount of the toner component was put into a Henschel mixer, premixed, and melt-kneaded with an extruder. Next, the obtained mixture was cooled and solidified, then coarsely pulverized with a hammer mill, and further finely pulverized with a jet mill. The obtained fine powder was classified with an airflow classifier to obtain black colored particles (toner particles) having a volume average particle size of 8.5 μm. Subsequently, 0.5 part by mass of hydrophobic silica particles (trade name: H3004, manufactured by Clariant Japan Co., Ltd.) was added to the obtained toner particles, and external addition processing was performed using a Henschel mixer.

  Further, it was mixed with a silicone resin coated carrier (particle size 50 μm) to prepare a black developer.

-Preparation of color toner (yellow)-
0.5 parts by mass of the infrared absorber A, 95 parts by mass of a polyester resin (used in the black toner), pigment: C.I. I. 10 parts by weight of Pigment Yellow 180, 1 part by weight of a charge control agent (CCA100, manufactured by Chuo Synthetic Chemical), and 0.5 parts by weight of wax: NP105 (Mitsui Chemicals) were prepared as toner components. The entire amount of the toner component was put into a Henschel mixer, premixed, and melt-kneaded with an extruder. Next, the obtained mixture was cooled and solidified, then coarsely pulverized with a hammer mill, and further finely pulverized with a jet mill. The obtained fine powder was classified with an airflow classifier to obtain yellow colored particles (toner particles) having a volume average particle size of 8.5 μm. Subsequently, 0.5 part by mass of hydrophobic silica particles (trade name: H3004, manufactured by Clariant Japan Co., Ltd.) was added to the obtained toner particles, and external addition processing was performed using a Henschel mixer.

  Further, it was mixed with a silicone resin coated carrier (particle size 50 μm) to produce a yellow developer.

-Preparation of color toner (magenta)-
0.5 parts by mass of the infrared absorber A, 95 parts by mass of a polyester resin (used in the black toner), pigment: C.I. I. 6 parts by weight of Pigment Red 122 (manufactured by Dainichi Seika), 1 part by weight of charge control agent (CCA100, manufactured by Chuo Synthetic Chemical), and 0.5 parts by weight of wax: NP105 (Mitsui Chemicals) were prepared as toner components. . The entire amount of the toner component was put into a Henschel mixer, premixed, and melt-kneaded with an extruder. Next, the obtained mixture was cooled and solidified, then coarsely pulverized with a hammer mill, and further finely pulverized with a jet mill. The obtained fine powder was classified with an airflow classifier to obtain magenta colored particles (toner particles) having a volume average particle diameter of 8.5 μm. Subsequently, 0.5 part by mass of hydrophobic silica particles (trade name: H3004, manufactured by Clariant Japan Co., Ltd.) was added to the obtained toner particles, and external addition processing was performed using a Henschel mixer.

  Further, it was mixed with a silicone resin coated carrier (particle size 50 μm) to prepare a magenta developer.

  The method described in Example 1 was evaluated using the developer.

In Comparative Example 1, the irradiation energy was set to 1.2 J in the evaluation tests of “(2) Fixability evaluation (crease evaluation)” and “(4) Void generation, gas generation” described in Example 1. An evaluation test changed to / cm ² was also performed.

  FIG. 7 shows the result of reflection spectrum measurement, and Table 1 shows the result of color evaluation when measuring the color difference ΔE. The light absorption rate of the black toner, the light absorption rate of the yellow toner, and the light absorption rate of the yellow toner are described above. Table 2 shows the ratio of the black toner to the light absorption rate (light absorption rate ratio), crease evaluation, ΔE, gas generation, and void generation evaluation results.

10 Image forming apparatuses 12K, 12Y, 12M, 12C Image forming units 14K, 14Y, 14M, 14C Photoconductors 16K, 16Y, 16M, 16C Chargers 18K, 18Y, 18M, 18C Exposure means 20K, 20Y, 20M, 20C Developer 22K, 22Y, 22M, 22C Cleaner 24K, 24Y, 24M, 24C Transfer device 26 Fixing device 28 Paper feed roller P Recording medium

Claims (3)

An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the image carrier;
A developing step of developing the electrostatic charge image with a black toner for light fixing and a color toner for light fixing to form a black toner image and a color toner image;
A transfer step of transferring the black toner image and the color toner image formed in the development step onto a surface of a transfer target;
A light fixing step of fixing the black toner image and the color toner image transferred to the surface of the transfer object by light exposure in an infrared region;
Have
The black toner is melted by light exposure in the infrared region in the light fixing step, and has a light absorption rate of 30% or more at the peak wavelength of the light in the infrared region irradiated in the light fixing step. % Of black toner,
The color toner contains an infrared absorber, is melted by light exposure in the infrared region in the light fixing step, and is light at a peak wavelength of light in the infrared region irradiated in the light fixing step. An image forming method wherein the absorption rate is 80% or more and 120% or less with respect to the light absorption rate of the black toner at the wavelength. An image carrier,
An electrostatic charge image forming apparatus for forming an electrostatic charge image on the surface of the image carrier;
A developing device for developing the electrostatic charge image with a black toner for light fixing and a color toner for light fixing to form a black toner image and a color toner image;
A transfer device for transferring the black toner image and the color toner image formed by the developing device to the surface of a transfer target;
An optical fixing device for fixing the black toner image and the color toner image transferred to the surface of the transfer medium by light exposure in an infrared region;
With
The black toner is melted by the light exposure of the infrared region by the light fixing device, and the light absorption rate at the peak wavelength of the light of the infrared region irradiated by the light fixing device is 30% or more 80 % Of black toner,
The color toner contains an infrared absorber, is melted by light exposure in the infrared region by the light fixing device, and is light at a peak wavelength of light in the infrared region irradiated by the light fixing device. An image forming apparatus having an absorption rate of 80% or more and 120% or less with respect to the light absorption rate at the wavelength of the black toner. A color toner for photofixing containing an infrared absorber having the strongest light absorption peak in the infrared region, and melted by exposure to light in the infrared region;
A black toner for light fixing that has a light absorption rate at a wavelength of the light absorption peak of 30% or more and 80% or less and melts by light exposure in an infrared region;
Have
A toner set in which a light absorption rate at a wavelength of the light absorption peak of the color toner is 80% or more and 120% or less with respect to a light absorption rate at the wavelength of the black toner.