JP2006084727A - Optical fixing color toner, and image forming method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color toner for image formation which ensures less change of a charge amount, can retain stable charging and developing properties over a prolonged period of time, and exhibits a hue hardly affected by an infrared absorbent. <P>SOLUTION: The color toner contains an aminium salt compound represented by formula (I) and a diimonium salt compound represented by formula (II), wherein a weight ratio (I:II) between the aminium salt compound and the diimonium salt compound is 95:5 to 60:40. In the formulae, R<SP>1</SP>-R<SP>8</SP>each denote H, alkyl, substituted alkyl, an alicyclic group, alkenyl, aralkyl or substituted aralkyl; and X<SP>-</SP>and Y<SP>-</SP>each denote an anion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming toner, and more particularly to a color toner suitable for an image forming method employing a light fixing method. The color toner of the present invention is used in various image forming apparatuses utilizing various image forming methods such as electrography, electrophotography, ionography, etc., such as electrophotographic copying machines, electrophotographic facsimiles, electrophotographic printers, and electrostatic printing machines. For example, it can be suitably used as a developer. The present invention also relates to a color image forming method and a color image forming apparatus using such an image forming color toner.

Conventionally, an electrophotographic image forming method widely used in a copying machine, a printer, a printing machine, etc. is generally positive or negative on the surface of a photoconductive insulator such as a photosensitive drum. Start by giving a uniform electrostatic charge. After such a uniform charging step, the electrostatic charge on the insulator is partially erased by irradiating the photoconductive insulator with a light image by various means to form an electrostatic latent image.
For example, an electrostatic latent image corresponding to image information can be formed on the photoconductive insulator by irradiating laser light to erase the surface charge of a specific portion. Next, a fine powder of developer called toner is attached to the latent image portion on which the electrostatic charge remains on the photoconductive insulator to visualize the latent image. Finally, the toner image obtained in this way is generally electrostatically transferred and fixed on a recording medium such as recording paper in order to obtain a printed matter.

  On the other hand, in the image forming method by ionography, a support drum having an electrostatic film is used as a dielectric member for carrying an electrostatic charge image, and ions are generated by ion (charged particle) generating means. An electrostatic image is formed on the surface, and the formed electrostatic image is developed with toner and visualized. Finally, the obtained toner image is subjected to a transfer and fixing process in the same manner as in the electrophotographic system described above to obtain a printed matter.

In the image forming method as described above, the fixing step is performed using a common technique.
For fixing the toner image after transfer, a method of solidifying and fixing the toner by melting it by pressure, heating, or a combination of these methods, or a method of solidifying and fixing after melting the toner by irradiating light energy, etc. However, a light fixing method (also referred to as 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, there is no need to pressurize the toner when fixing the toner, so there is no need to make contact (pressurization) with a fixing roller or the like. There is an advantage that there is little deterioration in image resolution (reproducibility). Also, there is no possibility that printing cannot be performed until the heat source (such as the fixing roller) reaches a desired temperature after the power is turned on, and a quick start can be performed in which printing can be performed immediately after the power is turned on. 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 ignited by heat. Further, there is an advantage that fixing is possible regardless of the material and thickness of the recording paper, such as glued paper, preprinted paper, and paper having different thicknesses.

  More specifically, the process of fixing the toner on the recording paper in the optical fixing method is as follows.

  In the transfer process, the toner image is transferred from the photosensitive drum or the like onto the recording paper. At this time, the toner adheres to the recording paper as a powder image to form an image. For example, if the image is rubbed with a finger, the image is broken. Next, the toner powder image on the recording paper is irradiated with flash light such as xenon flash. Then, the toner absorbs the light energy of the flash, softens by heating, and adheres to the recording paper. When the temperature is lowered after flash irradiation, the toner image is solidified and a fixed toner image is completed.

  What is important here is that the fixing toner image is peeled off from the recording paper due to bending or rubbing of the recording paper, causing deterioration of image quality, so-called fixing failure. For this purpose, it is necessary to increase the light absorption capability of the toner, promote the melting of the toner at the time of fixing, and design the toner to sufficiently penetrate into the paper and be firmly fixed.

  In the light fixing method, a light source commonly used as a fixing energy irradiation source is a xenon flash lamp. In general, xenon flash lamps have a light emission distribution over a wide range from ultraviolet to infrared, but the emission intensity is particularly strong in the near-infrared region of 800 to 1000 nm, so a toner with high fixing performance is developed. Therefore, establishment of a technique for efficiently absorbing light energy in this region is required. In particular, the demand for color prints has increased in recent years. Colorants used in color toners have absorption in the visible light region, but have low light absorption efficiency in the near-infrared region and good fixability in the light fixing method. There is a demand for practical use of the obtained color toner.

  On the other hand, in the black toner, the black colorant, which is a colorant, absorbs the near infrared region relatively well, so that it has already been put into practical use as an electrophotographic apparatus employing a light fixing system. In order to respond to the increasing demand for higher speed, further improvement in absorption efficiency is desired.

In response to these demands, it has been proposed to improve the fixing property by adding an infrared absorber to the color toner, and many related patent publications have been published:
Among these, Patent Documents 1 to 3 and the like include compounds having a light absorption ability in the near infrared region, such as aminium salts, indium oxide-based metal oxides, tin oxide-based metal oxides, zinc oxide-based metal oxides, tin. It is disclosed that the flash light absorption capability is enhanced by incorporating cadmium acid, a specific amide compound, or the like into the toner as an infrared absorber. In other words, in these patent documents, a material that absorbs light in the infrared region is added to the toner as an infrared absorber to achieve both colorization and photofixability. However, none of the proposed infrared absorbers still has the problem that they cannot provide sufficient fixability. In order to satisfy the photofixability, it is necessary to add a large amount of these infrared absorbers in the color toner.
i) Adverse effects on toner chargeability
ii) adversely affects toner hue
iii) There are problems such as an increase in toner cost, and the requirements cannot always be satisfied.

In relation to the proposition of achieving a colorization while maintaining a good color tone and having both a light fixing property in a trade-off relationship as described above, among the previously proposed infrared absorber groups, Examples of materials having an excellent performance balance include aminium salts and / or diimonium salt compounds, phthalocyanine and / or naphthalocyanine compounds, thiol nickel complex compounds, and the like by finely changing the chemical structure of these compounds. Ingenuity has been devised, such as increasing the light absorptivity of light and reducing the light absorption in the visible light region (colorless). Furthermore, proposals have been made to deal with the trade-off proposition by blending and using these different infrared absorbers. For toners that have a monochromatic color tone such as red, blue, green, etc., for which a strong colorant (a strong hiding power) colorant can be used as the toner colorant, these proposals work as they are and are at a practical level. There are cases where close performance can be imparted to the toner. However, when applying to toners that form a full-color image by laminating yellow, magenta, and cyan toners that require a certain degree of transparency (low concealment power), these methods are used to satisfy the requirements. The situation is not complete.
In addition, there is a material having strong charging characteristics in the group of the proposed infrared absorbers, and the charging characteristics of the material with respect to the developer charge amount during the process of image formation using the image forming apparatus. As a result, there are cases where stable image formation cannot be performed over a long period of time, and this measure is also required.
JP-A-7-191492 Japanese Patent Laid-Open No. 10-39535 JP-A-11-65167

  This invention makes it a subject to solve the said subject. That is, an object of the present invention is to provide a color toner for image formation that can use a light fixing method as an image fixing method, has good fixability of color toner, and can have a long life and stable environment by stabilizing charging, In particular, the object is to provide a negative-polarity toner and / or a full-color image-forming toner.

  Another object of the present invention is that, in addition to good color toner fixing properties, there is little variation in the charge amount due to the infrared absorber used, stable charging and development characteristics can be maintained over a long period of time, and the hue to the infrared absorber can be maintained. An object of the present invention is to provide a color toner for image formation with little influence.

In view of this situation, the present inventor has conducted intensive studies, and as a result, the aminium salt compound represented by the following formula (I) and the diimonium salt compound represented by (II) in a specific weight ratio in the toner. The present invention has been completed by finding that the above-mentioned problems can be solved by the combined use.
That is, the present invention provides the following toner, method and the like.

  <1> An aminium salt compound represented by the following general formula (I) and a diimonium salt compound represented by the following general formula (II) are both contained, and the aminium salt compound vs. the diimonium salt compound A color toner for light fixing, wherein the weight ratio (I: II) is 95: 5 to 60:40.

[Wherein, R ^{1 to} R ⁸ represent a hydrogen atom, an alkyl group, a substituted alkyl group, an alicyclic group, an alkenyl group, an aralkyl group or a substituted aralkyl group, and X ⁻ and Y ⁻ represent an anion. ]

<2> The color toner for photofixing according to <1>, wherein in the general formulas (I) and (II), the anions X ⁻ and Y ⁻ are the same.

  <3> A latent image forming step of forming an electrostatic latent image on the surface of the latent image carrier, and a developing step of developing the electrostatic latent image formed on the surface of the latent image carrier with toner to form a toner image. A transfer step for transferring the toner image formed on the surface of the latent image carrier to the surface of the transfer target; and a fixing for forming an image by photofixing the toner image transferred to the surface of the transfer target on the surface of the recording medium An image forming method comprising the steps of: <1> or <2>.

<4> The image forming method according to <3>, wherein image formation is performed using a plurality of toners, and development is performed sequentially using second to nth toners after development using the first toner. An image forming method that employs a sequential development batch photofixing process in which, after repeating n times, a toner layer of 1 to n layers is sequentially formed from a toner layer that is close to the recording medium, and then photofixing is performed collectively. In the color toner forming an arbitrary z-th toner layer, the ratio of the aminium salt compound to the diimonium salt compound a (z) [a = part by weight of the diimonium salt compound / (aminium salt compound weight) Part + diimonium salt compound weight part)] satisfies the following relational expression.
a (z-1) ≧ a (z)

<5> The image forming method according to <3>, wherein image formation is performed using a plurality of toners, and development is performed sequentially using second to nth toners after development using the first toner. An image forming method that employs a sequential development batch photofixing process in which, after repeating n times, a toner layer of 1 to n layers is sequentially formed from a toner layer that is close to the recording medium, and then photofixing is performed collectively. A color toner for forming an arbitrary z-th toner layer, wherein the toner colorant concealment degree C (z) satisfies the following relational expression.
C (z-1) ≧ C (z)

<6> The image forming method according to <3>, wherein image formation is performed using a plurality of toners, and development is performed sequentially using second to nth toners after development using the first toner. An image forming method that employs a sequential development batch photofixing process in which, after repeating n times, a toner layer of 1 to n layers is sequentially formed from a toner layer that is close to the recording medium, and then photofixing is performed collectively. In the color toner forming an arbitrary z-th toner layer, the ratio of the aminium salt compound to the diimonium salt compound a (z) [a = part by weight of the diimonium salt compound / (aminium salt compound weight) Part + diimonium salt compound weight part)] and the toner colorant hiding degree C (z) satisfy the following relational expression.
a (z-1) ≧ a (z)
C (z-1) ≧ C (z)

  <7> A latent image carrier, a charging unit for charging the surface of the latent image carrier, a latent image forming unit for forming a latent image on the surface of the charged latent image carrier, and a developer containing toner. And developing the latent image with the developer layer formed on the surface of the developer carrying member to form a toner image on the surface of the latent image carrying member, and transferring the toner image to a recording medium An image forming apparatus including: a transfer unit configured to transfer a toner image transferred onto the surface of the recording medium; and a fixing unit configured to form an image, wherein the toner is the toner according to <1> or <2>. An image forming apparatus, comprising:

  According to the present invention, the photofixability is good, and it is possible to extend the life and stabilization of the environment by stabilizing the charge, and in addition, there is little change in the charge amount due to the infrared absorber used, and stable charging over a long period of time. It is possible to provide a color toner for image formation that can maintain the development characteristics and has little influence on the hue by the infrared absorber. In addition, a toner having negative charging characteristics can be provided easily.

Hereinafter, the present invention will be described in detail by dividing it into a light fixing color toner, an electrophotographic developer, an image forming method and an image forming apparatus.
(Light fixing color toner)
The color toner for image formation according to the present invention basically includes an aminium salt compound represented by the general formula (I) and a diimonium salt compound represented by the following general formula (II) at a constant ratio. The composition can be the same as that of the color toner conventionally used in the electrophotographic process. That is, the color toner of the present invention is generally configured to include a binder resin and a colorant. As described above, various development methods are employed in the electrophotographic process, but the color toner of the present invention itself depends on the development method employed in the electrophotographic process in which it is to be used. Magnetic toner having magnetism may be used, or non-magnetic toner may be used. In the present invention, the term “color toner” includes full-color cyan, magenta, yellow toners, mono-color toners such as red and green, and black toner.

  In the color toner of the present invention, the binder resin used as a substrate is not particularly limited, but is preferably a thermoplastic resin made of a natural or synthetic polymer substance. A thermoplastic resin suitable as a binder resin can have various molecular weights and other characteristics depending on the desired effect. For example, the molecular weight (weight average molecular weight) of the binder resin is usually in the range of about 1,000 to 100,000, preferably in the range of about 5,000 to 50,000. In addition, such binder resin usually has a melting point of about 90 to 140 ° C and a glass transition point of about 55 to 70 ° C.

  As a binder resin suitable for the toner of the present invention, for example, epoxy resin, polyamide resin, polyester resin, styrene-acrylic resin, styrene resin, acrylic resin, polyether polyol resin, phenol resin, silicone resin, polyvinyl resin, polyurethane resin, Examples thereof include polybutadiene resin. These binder resins may be used alone or in combination of two or more resins. For example, when using a polyester resin, if desired, a linear polyester resin and a polyester resin containing a crosslinking component may be mixed and used.

  The binder resin particularly suitable for the practice of the present invention is preferably a polyester resin from the viewpoint of low odor. The polyester resin 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. 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. Further, in order to crosslink the polyester resin, a trivalent or higher carboxylic acid component can be mixed and used as another acid component. Examples of the trivalent or higher carboxylic acid component include 1,2,4-benzenetricarboxylic acid, 1,3,5-benzenetricarboxylic acid, other polycarboxylic acids, and anhydrides thereof.

Further, in such a polyester resin, usually, 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%. If the amount of the bisphenol A alkylene oxide adduct is less than 80 mol%, the amount of the monomer that causes the generation of odor relatively increases, which is not preferable.
Here, as a bisphenol A alkylene oxide adduct, the compound represented by the following general formula is mentioned, for example.

HO- [Alk-O] x-C6H6-C (CH3) 2-C6H6- [O-Alk] y-OH

(In the above formula, Alk-O may be the same or different and represents a derivative obtained by oxidizing an alkylene group such as an ethylene group or a propylene group, and x and y are each an integer of 1 or more. is there)
Examples of such compounds 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 0.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane, and the like. it can. These compounds may be used alone or in combination of two or more.

Among the above-mentioned compounds, particularly suitable compounds are, for example, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, and the like.

  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, Diols such as 1,5-pentanediol and 1,6-hexanediol, and other dihydric alcohols such as bisphenol A and hydrogenated bisphenol A.

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

  In the color toner of the present invention, the colorant to be dispersed in the binder resin includes many known dyes and pigments, and can be arbitrarily selected and used. Suitable colorants are not limited to those listed below. For example, carbon black, lamp black, iron black, ultramarine, nigrosine dye, ferrite, magnetite, etc. (for black toner), or aniline blue , Calco oil blue, Ultramarine blue, DuPont oil red, Anthraquinone, Quinoline yellow, Methylene blue chloride, Phthalocyanine blue, Phthalocyanine green, Halogenated phthalocyanine, Anilide compounds, Benzimidazolone, Hansa yellow, Rhodamine 6C lake, Chrome yellow, Quinacridone , Benzidine Yellow, Malachite Green, Malachite Green Hexalate, Malachite Green Oxalate, Oil Black, Azo Oil Black, Rose Bee Galle, can be mentioned monoazo dyes and pigments, disazo pigments, such as trisazo dye or pigment (for color toners). These colorants may be used alone or else mixed to be used in order to obtain a desired toner color.

  Although the content of the colorant in the toner as described above can be widely changed according to the desired result, it is preferable to obtain the best toner characteristics, that is, the color strength of printing, the toner In consideration of the shape stability of the toner and the scattering of the toner, it is usually in the range of 0.1 to 20 parts by weight, preferably in the range of 0.5 to 10 parts by weight with respect to 100 parts by weight of the toner.

As described above, the electrophotographic color toner of the present invention uses the above-described aminium salt compound (I) and diimonium salt compound (II) in a certain ratio range in addition to the binder resin and the colorant. Is essential.
In the formula, R ^{1 to} R ⁸ represent a hydrogen atom, an alkyl group, a substituted alkyl group, an alicyclic group, an alkenyl group, an aralkyl group or a substituted aralkyl group. Among them, an alkyl group, a substituted alkyl group, and an alkenyl group An aralkyl group or a substituted aralkyl group is preferred.
X and Y in the formula are anions. For example, perchloric acid (ClO ₄ ⁻ ), boroboric acid (BF ₄ ⁻ ), trichloroacetic acid (CCl ₃ COO ⁻ ), trifluoroacetic acid (CF ₃ COO ^-), picric acid _{((NO 2) 3 C 6} H 2 O -), hexafluoroarsenate (AsF ₆ -), hexafluoroantimonate (SbF ₆ -), benzenesulfonic acid (C ₆ H ₅ SO ₃ ^-), ethanesulfonic acid ^{_{(C 2 H 5 SO 3 -}} ), phosphate (PO ₄ ^2-), sulfate (SO ₄ ^2-), chlorine (Cl ^-), toluenesulfonic acid, nitric acid and the like.
Hereinafter, the utility of the combined use will be described.

According to the study by the present inventors, the aminium salt-based compound represented by the above formula (I) has the following characteristics.
1. Although it exhibits light absorption characteristics over a wide frequency range of wavelengths from 800 to 2000 nm, the molar absorbance ε at the maximum absorption wavelength is about 2 to 3, which is a medium level among the proposed infrared absorbers. stay. For this reason, in order to impart photofixability to a color toner using only an aminium salt compound, it is necessary to add at least 0.5 wt%, more preferably 1 wt% to several wt% ( Naturally, the optimum amount of addition differs depending on the toner material and the amount of light irradiation energy of the fixing unit).
2. The color tone of the compound itself is mostly light green, and the hiding power of the compound itself with respect to the color tone surface is also small. For this reason, the degree of change in color tone due to the addition of an infrared absorber is small among the previously proposed infrared absorbers.
3. Regarding the charging characteristics, the compound itself exhibits a moderately positive charging property, but its degree is not so strong, and does not greatly interfere with the functions of various charge control agents added to the toner for the purpose of charge control. By selecting an appropriate charge control agent, a toner having desired charge characteristics can be designed.

On the other hand, the diimonium salt compound represented by the above formula (II) has the following characteristics.
1. It exhibits optical absorption characteristics over a wide frequency range of wavelengths from 800 to 2000 nm, and the molar absorbance ε at the maximum absorption wavelength is approximately 10 to 14. Among the proposed infrared absorbers, it has a high level of light absorption capability. In order to impart photofixability to a color toner using only a diimonium salt compound, it is necessary to add at least 0.2 wt%, more preferably 0.5 wt% to several wt% (naturally Of course, the optimum amount depends on the material of the toner and the amount of light irradiation energy of the fixing unit).
2. The color tone of the compound itself is often dark green to black, and the hiding power of the compound itself with respect to the color tone surface is also great. The degree of color change due to the addition of an infrared absorber is also large.
3. Concerning charging characteristics, it shows a fairly strong positive chargeability. Even when various charge control agents are added to the toner for the purpose of charge control, it is often difficult to design a toner having desired charge characteristics. This tendency tends to be prominent when a two-component developer prepared with a toner added with the infrared absorber is run for a long time. In particular, the effect is significant when toner is prepared as a negative developer.

The present inventors make use of an aminium salt compound and a diimonium salt compound having these advantages and problems in a suitable ratio in the toner so as to compensate for each other's problems and achieve a high level of balance. The inventors have found that an excellent color toner for light fixing can be obtained, and have made the present invention.

That is, a diimonium salt compound that has moderate infrared light absorption and charging characteristics, has a light color tone and is based on an aminium salt compound that has strong chargeability and color tone, but has high infrared light absorption characteristics By adding an appropriate amount, it is sufficiently practical for application to full color toners that require high transparency in terms of charging characteristics and colorability (color turbidity) while having strong infrared light absorption characteristics. It has been found that an infrared light absorption characteristic that can be tolerated can be achieved. According to the study by the present inventors, the ratio (parts by weight) is required to be 95: 5 to 60:40 in terms of the ratio of the aminium salt compound to the dimonium salt compound.
According to the study by the present inventors, a toner containing an aminium salt compound and a diimonium salt compound blended at this ratio can be adjusted as a negative developer, and has stable charging and developing characteristics over a long period of time. It became clear that he played.

According to the study by the present inventors, it is desirable that the anions of the aminium salt and the diimonium salt used by blending are common ions. This is because the aminium salt and the diimonium salt coexist in the toner, so that ion exchange occurs between neighboring salts. As a result, an aminium salt and a diimonium salt having an anion different from the original anion are generated. This is because desired infrared light absorption characteristics, charging characteristics, and colorability may not be maintained.

Further, according to the inventors' investigation, when the present invention is applied to an image forming method and an image forming apparatus for forming a full color image using three primary colors of yellow, magenta, and cyan, Among the color toners that are laminated and developed accordingly, the toner of the color tone that forms a powder image closer to the recording medium such as paper has the highest diimonium salt content, and the content decreases in turn, and the paper It is desirable to blend the blend ratio so that the content of dimonium salt in the toner farthest from the recording medium is reduced.
This is because, when flash light is irradiated from the upper part of the laminated toner powder image, the uppermost toner powder image is irradiated with the strongest light energy, and the next toner layer passes through the uppermost toner layer. In this way, irradiation of light energy attenuated is performed. The irradiated light energy gradually attenuates as it passes through the toner layer, and the weakest light energy irradiation is performed on the toner layer closest to the recording medium such as paper.

On the other hand, in order to ensure a good color tone as a full-color image, it is desirable that the laminated toner layers are melted as homogeneously as possible, and the disturbance of the interface between the melted toner layers is minimized. It is desirable that the toner closest to the recording medium such as paper is in a molten state similar to the uppermost toner.

  In order for the toner to melt sufficiently even with attenuated light, it is desirable to add a high proportion of a diimonium salt having a high infrared light absorption capability to the toner.

  In addition, when the diimonium salt is blended in a high ratio, the influence (color turbidity) on the color tone becomes strong as it is. This problem can be addressed by selecting a colorant having a high hiding power as a colorant used in a toner containing a high proportion of diimonium salt.

According to the study by the present inventors, when a colorant having a high hiding power is used as the toner colorant used in the toner layer laminated on the upper layer of the laminated toner layer (the position farthest from the recording medium such as paper), the entire full-color image is obtained. However, it is not preferable because it is affected by the toner color. However, if a toner having a highly transparent colorant is arranged in the upper layer, and a toner having a colorant having a higher concealment degree is arranged in the lower layer, the color image as described above has a specific toner color. It is not affected and a full color image having excellent color reproducibility can be obtained.
According to the study by the present inventors, diimonium in a range of 5% to 10% in terms of parts by weight per color toner layer laminated in order from the upper layer (the toner layer that receives the most light irradiation) to the lower toner layer. By increasing the addition ratio of the salt content, the light absorption characteristics of the color toners can be balanced, and the present invention can be more suitably implemented.

Furthermore, in the implementation of the present invention using such an infrared absorber in combination, the image fixing device for fixing a toner powder image on a recording medium such as recording paper will be described in more detail hereinafter. A halogen exposure apparatus, a flash exposure apparatus, or the like having an emission peak in the infrared region in a wavelength region of at least 750 to 1200 nm can be advantageously used.

A conventional inorganic or organic infrared absorber may be additionally added to the color toner of the present invention in order to improve fixing. Specific examples of the inorganic infrared absorbent and the organic infrared absorbent include vanadyl naphthalocyanine, cyanine, nickel complex, phthalocyanine series, ytterbium oxide compound, and the like.
The addition amount of the known infrared absorber is preferably in the range of 0.05 to 5 parts by weight and more preferably in the range of 0.1 to 2 parts by weight with respect to 100 parts by weight of the toner. .

The color toner of the present invention can contain a charge control agent in order to control the charging performance of the toner. The charge control agent used in the present invention is not particularly limited as long as it has the ability to impart charge to the toner. However, in consideration of the small influence on the hue of the toner in the color toner, colorless and light-colored ones are preferable. . Preferably, a quaternary ammonium salt (colorless), nigrosine dye (black), triphenylmethane derivative (blue), etc. as a positive charge control agent, zinc naphtholate complex (colorless), zinc salicylate complex (colorless) Boron compounds can be used as negative charge control agents. Further, these charge control agents are usually used in a range of 0.05 to 10 parts by weight with respect to 100 parts by weight of the toner.

The color toner of the present invention can also contain a wax for the purpose of further improving the fixing property of the toner. Examples of suitable waxes include polyolefins such as polyethylene and polypropylene, fatty acid esters, paraffin wax, carnauba wax, amide wax, and acid-modified polyethylene. These waxes may be used alone or in combination of two or more. As the waxes, those having a softening temperature of 150 ° C. or lower are particularly preferable, and those having a softening temperature lower than the melt softening temperature of the binder resin are particularly preferable.

The color toner of the present invention can further contain an external additive. For example, the color toner of the present invention can contain white inorganic fine powder for the purpose of improving fluidity. Suitable inorganic fine powders include, for example, silica fine powder, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, silica sand, clay, mica, wollastonite, 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. The ratio of the inorganic fine powder mixed with the toner is usually 0.01 to 5 parts by weight, preferably 0.01 to 2.0 parts by weight, based on 100 parts by weight of the toner. In addition, known materials such as silica, titanium, resin fine powder (resin particles such as polystyrene, PMMA, melamine resin), and alumina can be used in combination with the inorganic fine powder. 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 color toner for image formation according to the present invention can be prepared according to various procedures using the toner component as described above as a starting material. For example, the color toner of the present invention is known in the art such as a mechanical pulverization method in which a resin lump in which a colorant is dispersed is pulverized and classified, and a polymerization method in which monomers are polymerized while incorporating the colorant to produce fine particles. Can be prepared using

For example, when the color toner of the present invention is prepared by a mechanical pulverization method, a toner resin component such as a binder resin, a colorant, an infrared absorbing compound of the present invention, waxes, and a charge control agent is mixed and then the resulting mixture is obtained. Is melt-kneaded using a kneader or an extruder. Further, the melt-kneaded material is coarsely pulverized and then finely pulverized by a jet mill or the like, and toner particles having a target particle diameter are obtained by an air classifier. Further, an external additive is added to complete the final toner.

In addition, when a color toner is prepared by a polymerization method, a suspension polymerization method and an emulsion polymerization method can be mainly applied. When prepared by suspension polymerization, monomers such as styrene, butyl acrylate and 2-ethylhexyl acrylate, cross-linking agents such as divinylbenzene, chain transfer agents such as dodecyl mercaptan, colorants, charge control agents, infrared absorbing property of the present invention A monomer composition is prepared by mixing a compound, waxes, a polymerization initiator and the like. Thereafter, the monomer composition is put into an aqueous phase containing a suspension stabilizer such as tricalcium phosphate and polyvinyl alcohol, and a surfactant, and a rotor-stator emulsifier, a high-pressure emulsifier, and an ultrasonic emulsifier. After preparing the emulsion using a machine, the monomer is polymerized by heating. After the polymerization is completed, the particles are washed and dried, and an external additive is added to obtain final toner particles.

When preparing color toners by emulsion polymerization, monomers such as styrene, butyl acrylate and 2-ethylhexyl acrylate are dissolved in water in which a water-soluble polymerization initiator such as potassium persulfate is dissolved. A surfactant such as is added and heated and polymerized while stirring to obtain resin particles. Thereafter, the infrared absorbing compound, colorant, charge control agent, wax and the like of the present invention are added to the suspension in which the resin particles are dispersed to adjust the pH, stirring strength, temperature, etc. of the suspension. As a result, the resin particles and the infrared-absorbing compound powder are heteroaggregated. Further, the system is heated to a temperature equal to or higher than the glass transition temperature of the resin to fuse the heteroaggregates to obtain toner particles. Thereafter, the particles are washed and dried, and external additives are added to obtain final toner particles.

(Image forming method)

  In the electrophotographic process, as described above, an electrostatic charge is applied to the surface of a photoconductive insulator such as a photoconductive drum, and an electrostatic image is formed by irradiating the surface with an electrostatic image. Next, a developer made of toner is attached to the latent image portion on the photoconductive insulator to visualize the latent image. Thereafter, the obtained toner image is electrostatically transferred to a recording medium such as recording paper, and further fixed. In the present invention, as described in detail below, a method of solidifying and fixing after irradiating light energy to melt the toner, that is, a light fixing method (in other words, a flash fixing method) is adopted.

  The developing method employed in the practice of the present invention is not particularly limited, and a suitable developing method can be selected and employed each time. In other words, in the present invention, it is possible to prepare and use an optimum developer for each developing method while satisfying the essential conditions required for the color toner of the present invention. The development methods that can be employed in the present invention thus include both the two-component development method and the one-component development method widely used in this technical field.

  In the two-component development method, toner particles are brought into contact with carrier particles made of magnetite, ferrite, iron powder, glass beads, or the like or a resin coating thereof, and the toner is attached to the carrier using frictional charging. In this method, the toner is guided to the latent image portion for development. That is, in the case of this method, the developer is configured by combining the toner and the carrier. The particle size of the carrier particles is usually 30 to 200 μm, and the mixing ratio of the toner particles to the carrier particles is usually 0.5 to 30% by weight. The developing method used in this method includes a magnetic brush developing method.

  As a method that omits the use of a carrier in the two-component development method, a one-component development method is also known. Since this system does not use a carrier, it does not require a mechanism such as toner density control, mixing and stirring, and has the advantage that the apparatus can be miniaturized. In the one-component developing method, generally, a toner layer is formed as a uniform thin film on a metal developing roller, and the toner layer can be guided to a latent image portion for development. The application of charge to the toner particles on the developing roller can be performed by frictional charging or electrostatic induction. For example, in the case of a one-component developing method based on frictional charging, magnetic toner is used in the BMT method and FEED method with contact, but non-magnetic toner is used in the touchdown method with contact. In addition, since there are many electrophotographic publications regarding the electrophotographic process and the developing method employed therein, the publications can be referred to for details.

In the image forming method of the present invention, a light fixing method is used as a toner fixing method in a step of fixing an image visualized by using a developer after being transferred to a recording medium. For light fixing of the transferred toner image, flash light, far infrared light, halogen light, or the like can be advantageously used as a light source. As the flash light, an appropriate light can be used according to the specification of the flash fixing device to be used, from light in a wide wavelength range from visible light to near infrared light. In particular, toner can be efficiently fixed using a xenon lamp as flash light. In addition, the emission energy per unit area of flash light indicating the lamp intensity of xenon is expressed by the emission energy density (input standard) in consideration of full-color image formation in which several toner layers are stacked to form an image. Thus, it is preferably in the range of 2.0 to 4.0 J / cm ² . Luminous energy density, do not fixed too small than 2.0 J / cm ^2, too large than 4.0 J / cm ² on the opposite burnt toner voids or sheets, smoke or malodor caused by excessive melting of the toner occurs, such as Problem arises. In particular, this problem becomes remarkable in the fixing process of the black toner used for image formation together with the toner of the present invention, so that attention is required.
The light emission energy density (input standard): S (J / cm ² ) is expressed by the following equation.

S = ((1/2) × C × V ² ) / (u × l) / (n × f)
Number of lamps: n (books)
Lighting frequency: f (Hz)
Input voltage: V (V)
Capacitor capacity: C (μF)
Process transfer speed: u (mm / s)
Print width: l (mm)

Moreover, although the light emission time of flash light can be widely changed in accordance with the light emission energy density of the flash light, it is usually preferably in the range of 500 to 3,000 μ / s. If the light emission time of the flash light is too short, the toner cannot be melted sufficiently to increase the flash fixing rate. If the flash light emission time is too long, the toner fixed on the recording medium may be overheated.

Further, halogen light fixing (infrared oven fixing) may be used in combination with flash fixing in order to obtain good fixing of color toner and long-term stability.

More specifically, the color image forming method according to the present invention can be carried out basically in the same manner as the conventional image forming method except for the above differences. As a preferred example, formation of an electrostatic latent image by image exposure is performed by various means after applying a positive or negative uniform electrostatic charge to the surface of a photoconductive insulator such as a photosensitive drum. By irradiating the photoconductive insulator with a light image, the electrostatic charge on the insulator is partially erased to form an electrostatic latent image. For example, an electrostatic latent image corresponding to image information can be formed on the photoconductive insulator by irradiating laser light to erase the surface charge of a specific portion.

  Next, the formed electrostatic latent image is visualized by development. This can be done by adhering a fine powder of developer containing the toner of the present invention to the latent image portion where the electrostatic charge remains on the photoconductive insulator.

After completion of the development process, the visualized image is transferred to a recording medium. This can be generally performed by electrostatically transferring the obtained toner image to a recording medium such as recording paper.

Finally, according to the present invention, the toner image transferred in the above transfer step is melted by flash fixing and fixed on a recording medium. Through such a series of processing steps, the desired printed matter can be obtained.

Since an image forming method based on electrophotography is widely known in this technical field, a detailed description thereof is omitted here. Further, even if another image forming method such as ionography is applied in place of the electrophotographic method, a satisfactory effect can be obtained.

<Image forming apparatus>
Next, an example of the image forming apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an example of an image forming apparatus of the present invention. In FIG. 1, 1a to 1d are charging means, 2a to 2d are exposure means, 3a to 3d are electrostatic charge image carriers (photoconductors), 4a to 4d are developing means, 10 is an intermediate transfer member (transferred member), 20 is a black developing unit, 30 is a cyan developing unit, 40 is a magenta developing unit, 50 is a yellow developing unit, 60a to 60d are first transfer means (transfer rollers), 61, 62, 63, and 64 are rollers, and 70 Is a second transfer means (transfer roller), 71 is a primary transfer voltage supply means, 72 is a secondary transfer voltage supply means, 80 is a light fixing means, 90 is a cleaning means, 100 is an image forming apparatus, and 200 is a recording target. Represents the body.

  An image forming apparatus 100 shown in FIG. 1 includes 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, an intermediate transfer member 10, and an inner peripheral surface thereof. The rollers 61, 62, 63, and 64 are arranged in contact with the intermediate transfer body 10, and the inner peripheral surface of the developing unit via the intermediate transfer body 10 so as to press the photoreceptor of each developing unit. The arranged transfer rolls 60a, 60b, 60c, 60d, the primary transfer voltage supply means 71 for supplying voltage to these four transfer rolls, and the transfer roll 64 are arranged so as to press the intermediate transfer body 10. The transfer roll 70, the secondary transfer voltage supply means 72 for supplying voltage to the transfer roll 70, the cleaning means 90 for cleaning the outer peripheral surface of the intermediate transfer body 10, and the roll 64 The optical fixing unit 80 for irradiating light on the side in contact with the intermediate transfer member 10 of the recording medium 200 to pass between the transfer member 10 to nip portion between the transfer roll 70 in the direction of an arrow in the figure, and a.

  The black 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 photosensitive member 3a in a clockwise direction. Further, the transfer roll 60a is interposed via the intermediate transfer member 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. Opposed. 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 the magenta toner of the present invention is stored in the developing unit 4c of the magenta developing unit 40, and the developing units of the other developing units correspond to the respective colors. Toner for light fixing is stored.

  Further, on the outer peripheral surface of the intermediate transfer member 10, a black developing unit 20, a cyan developing unit 30, a magenta developing unit 40, a yellow developing unit 50, a cleaning unit 90 (peeling claw side), and a transfer roll 70 are arranged in this order. Arranged so as to be in contact with the outer peripheral surface, the transfer rolls 60a, 60b, 60c, 60d, the cleaning means 90 (roll side), the rolls 64, 63, 62, 61 are arranged in this order.

  Next, image formation using the image forming apparatus 100 will be described. First, in the black developing unit 20, the surface of the photoreceptor 3a is uniformly charged by the charging unit 1a while rotating the photoreceptor 3a in the clockwise direction. Next, the surface of the charged photoconductor 3a is exposed by the exposure means 2a, whereby a latent image corresponding to the black component image of the original image to be copied is formed on the surface of the photoconductor 3a. Further, the black toner stored in the developing means 4 is applied on the latent image to develop it to form a black toner image. This process is similarly performed in the cyan developing unit 30, the magenta developing unit 40, and the yellow developing unit 50, and a toner image of each color is formed on the surface of the photoreceptor of each developing unit.

  The toner images of the respective colors formed on the surface of the photosensitive member are sequentially transferred onto the intermediate transfer member 10 that rotates counterclockwise by the action of the transfer potential by the transfer rolls 60a to 60d so as to correspond to the original image information. The toner images are laminated on the outer peripheral surface of the intermediate transfer member 10 to form a full color laminated toner image of black, cyan, magenta, and yellow.

Next, when the laminated toner image on the intermediate transfer body 10 is conveyed to the nip portion between the roll 64 and the transfer roll 70, it is transferred onto the recording medium 200 by the action of the transfer potential by the transfer roll 70. . Then, the laminated toner image transferred onto the recording medium 200 is conveyed to the light fixing unit 80 where it is irradiated with light from the light fixing unit 80 and melted, and is fixed onto the recording medium 200. A full color image is formed.
The toner remaining on the intermediate transfer body 10 after the transfer of the laminated toner image to the recording medium 200 is removed by a cleaning means 90 provided with a peeling claw such as a cleaning blade.

In the electrophotographic apparatus shown in FIG. 1, a developer prepared by mixing a carrier with the color toner of the present invention is stirred by a stirring screw and is frictionally charged. The frictionally charged developer is guided along a predetermined circulation path, reaches the developing means 4, and is further conveyed to the photoreceptor 3. Although the photoconductor 3 varies depending on the latent image forming method, the photoconductor is a photoconductive material, for example, an organic photoconductor such as polysilane, phthalocyanine, or phthalopolymethine, an inorganic photoconductor such as selenium or amorphous silicon, or an insulating material. Can be formed from the body. In particular, an amorphous silicon photoreceptor is preferable from the viewpoint of long life.

Examples of the present invention are shown below, but the present invention is not limited by the following examples.
In addition, the measurement used for the Example and the comparative example and the evaluation method are as follows.

Measurement of charge amount:
The charge amount was measured by a magnet blow-off method. The measuring device is obtained by changing the developer holding mesh portion of the blow-off charge measuring device (manufactured by Kyocera Chemical Co.) to a magnet made of samarium cobalt. There were three measurement environments: RT environment (25 ° C., 50% RH), high temperature and high humidity HH (32 ° C., 80% RH), and LL low temperature and low humidity (15 ° C., 20% RH). The absolute value of the charge amount is optimally 15 to 25 μC / g, the print density is low at 25 μC / g or less, and the fog occurs at 15 μC / g or less.

Evaluation of charge retention:
The ratio between the HH charge amount and the LL charge amount was determined and used as an evaluation scale for charge retention. Those having a charge retention of 70% or more were evaluated as good (◯).

Evaluation of charging stability:
Compare the charge amount of the developer installed in the image forming apparatus before and after running evaluation, and the charge amount after running evaluation is within ± 25% of the charge amount before running evaluation is good (○), within ± 10% Some were considered excellent (（).

Measurement of print density and color gamut:
The image print density on plain paper on which the toner image was fixed was measured using a spectrophotometer. X-rire938 (manufactured by X-rite) is used as the spectrocolorimeter, and measurement is performed under the conditions of light source D50, 2 ° (backing white), and the color tone is excellent within ΔE5 from the reference color. ΔE5 -10 to good ○, ΔE10 to 15 was determined to be a boundary region Δ, and ΔE values were determined to be defective regions ×.
Regarding the color density, the density (STATUS A) at the maximum absorption wavelength of the toner is best when it is 1.1 or more, 1.0 to 1.1 is good, and 0.8 to 1.0 is the boundary region Δ. The case of less than that was determined to be a defective area x. A 1-inch square solid image (after fixing) was used for colorimetry. The reference color here refers to the color of an image formed under the same composition and evaluation conditions (except that the fixing method is oven fixing) except that the infrared light absorber is not included. The color difference ΔE is an index indicating the degree of “color turbidity” due to the addition of the infrared light absorber in the image forming material.

  In addition, for the color gamut of a full color image, a powder image that forms a six-color image of yellow, cyan, magenta, red, green, and blue under the conditions that the toner to be evaluated and the toner stacking order are formed is created. Thereafter, flash light irradiation was performed to obtain a fixed image, and the color tone of each color was measured by the above method, and the color tone of each color was plotted on the a * / b * plane. Next, toners of the same composition are prepared except that each color toner and the infrared light absorber are not included, and similarly, six-color images of yellow, cyan, magenta, red, green, and blue are formed, and then oven-fixed. To obtain a fixed image, measured in the same manner, and plotted the tone of each constant color on the a * / b * plane. Then, the inner area surrounded by the plots of the two is compared, and the inner area of the plot obtained from the toner containing the infrared light absorber is the inner area of the plot obtained from the toner not containing the infrared light absorber. The value divided by was used as an evaluation scale.

Toner fixing rate measurement:
Fixability was evaluated by a tape peeling test method. In the tape peel test, an adhesive tape (Scott Mending Tape; manufactured by 3M) is lightly applied on the fixed image, and the cylindrical block is rolled in the circumferential direction so that the tape adheres to the image surface at a linear pressure of 250 g / cm. After that, the tape is peeled off, and the optical density ratio of the image before and after the tape is peeled off is used as a fixing ratio. The optical density before sticking the tape (OD1) and the optical density after peeling the tape (OD2) From this, the fixing rate is derived using the following formula. In the present invention, a fixing ratio of 95% or more was determined to be the best ◎, 95 to 90% was determined to be good ◯, 90 to 80% was determined to be a boundary region Δ, and a region below that was determined to be a defective region ×. In this case, the optical density was also measured using a spectrocolorimeter (X-rire938, manufactured by X-rite) in the same manner as described above, based on the STATUS A density at the maximum absorption wavelength of the toner.
・ Fixing rate (%) = OD2 / OD1 × 100 (STATUS A)

Measurement of fog:
The state of occurrence of fog (dirt background) on plain paper on which the toner image was fixed was visually confirmed. Good (○) when no fogging is observed, acceptable (△) when slight fogging is observed, and (X) when no unacceptable fogging is observed. did.

Concealment measurement:
5 parts by weight of toner is completely dissolved in 95 parts by weight of methyl ethyl ketone, and then uniformly applied onto a 100 μm thick polyethylene terephthalate film using a bar coater so that the film thickness after drying is 20 μm. A sample in which the pigment dispersion is applied to the dried film is evaluated based on the hiding rate test paper method of JIS K5101.
Using white paper (reflectance 80 ± 1) and black paper (reflectance 2 or less) specified in JIS K5101, the above samples are brought into close contact with each paper, and the spectrocolorimeter (CM-3700d, manufactured by Minolta) from the sample side. ) To measure the lightness and obtain the degree of concealment.

Concealment degree (%) = (LB / LW) x 100
LB: Lightness on black paper
LW: Lightness on white paper

Void rating:
The obtained 1-inch square image was observed with a microscope, the size and quantity of voids (void defects) were examined, and evaluated according to the following criteria. Regarding the size and quantity of voids (void defects), a photomicrograph of the image fixing image was taken, the photographic image was analyzed with an image analyzer (Luzex 2000, manufactured by Nireco), and all of the image information The ratio of the “void” area to the image area was determined, and this was quantified as a concealment rate (void).
○: No void Concealment rate (void) of 90% or more △: Small void Concealment rate (void) of 80% or more and less than 90% (level at which the presence of voids can be seen by visual inspection)
X: Large void Concealment rate (void) less than 80% (a level at which defects can be recognized visually, causing a practical problem)

[Examples 1-5, Comparative Examples 1-3]
(Optimization of the addition ratio of aminium salt / dimonium salt)
First, the following experiment was performed in order to obtain the optimum blend ratio of the aminium salt and the diimonium salt. At this time, in order to clearly determine the side effect of the diimonium salt, that is, the degree of influence on the charging problem and the color turbidity problem, the color tone of the evaluation toner was yellow, and the charging characteristic of the toner was negative.

Preparation Example 1
(1) Preparation of carrier Magnetite particles having a diameter of 60 µm were used as a carrier core material, and the surface thereof was coated with a silicone resin to obtain a magnetite carrier coated with the silicone resin. The coating amount for the carrier core was approximately 2% by weight.

(2) Preparation of binder resin (polyester resin) 1.0 mol of polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.2) -2,2- Bis (4-hydroxyphenyl) propane 9.0 mol, terephthalic acid 4.6 mol, isophthalic acid 4.6 mol, and 5.0 g of dibutyltin oxide were placed in a glass four-necked flask, and a thermometer, stainless steel A stirrer bar, a falling condenser, and a nitrogen inlet tube were attached.
The reaction was completed by reacting the reaction mixture in the four-necked flask in a mantle heater under a nitrogen stream at 220 ° C. for 3 hours, at 240 ° C. for 3 hours, and at the same temperature for 2 hours at a reduced pressure of 60 mmHg. did. A polyester resin having a weight average molecular weight of 5,500, a glass transition temperature of 65 ° C., a softening point of 112 ° C., and an acid value of 10 was obtained.

(3) Preparation of color toners 15 types of yellow color toners for flash fixing having the composition shown in Tables 1 and 2 below were produced. The following materials were used as raw materials.

Binder resin; the polyester resin (2)
Infrared light absorber (A): aminium perchlorate compound (NIR-AM1; manufactured by Nagase Chemtech Co., Ltd., R ^{1 to} R ⁴ = C ₂ H ₅ )
Infrared light absorber (B): diimonium perchlorate compound (NIR-IM1, manufactured by Nagase Chemtech, R ^{5 to} R ⁸ = C ₂ H ₅ )
Colorant: Pigment Yellow 180 (P-HG; manufactured by Hoechst)
Negative charge control agent: E-89 (manufactured by Orient Chemical)
Polypropylene wax: NP105 (Mitsui Chemicals)

  The above materials were put into a Henschel mixer, premixed, kneaded with an extruder, and then coarsely pulverized with a hammer mill. Further, this was finely pulverized with a jet mill and classified with an airflow classifier to obtain a yellow toner having a volume average particle diameter of about 8.5 μm. Next, 0.5 part by weight of hydrophobic silica fine particles (H2000 / 4; manufactured by Clariant) was added as an external additive, the external additive treatment was performed with a Henschel mixer, and the surface of the yellow toner A was coated with the external additive. ~ H was obtained.

  Various properties were determined for each yellow toner obtained as described above. The results are shown in Tables 1 and 2. The measurement procedure will be described later.

  Next, the yellow toner, 4.5 parts by weight, and 95.5 parts by weight of the above-mentioned silicone-based resin-coated magnetite carrier are mixed by a ball mill to form a two-component developer. A toner image was formed on a recording medium using the printer No. 1 and its fixability was evaluated.

  FIG. 1 is a diagram schematically showing a partial outline of a two-component development type prototype image forming apparatus 1 as an example. The apparatus 1 is, for example, a high-speed development type with a process speed of 1100 mm / s.

In this example, development and transfer were performed using one developing unit of the image forming apparatus (adopting a xenon flash fixing method), and further, the potential applied to the flash lamp was displaced in the fixing step. Thereby, the light energy which a flash lamp emits can be changed per unit area of a recording medium (paper). In Examples 1 to 10 and Comparative Examples 1 to 5, light energy of 1.8 to 4.2 J / cm ² and light emission time of 1500 μs was applied, and the yellow toner A powder image was melted on the paper. From the solidified, a fixed image was obtained. The emission spectrum of the xenon light source used had a high emission intensity in the wavelength range of 700 to 1500 nm as schematically shown in FIG.
Next, the fixability, drawing characteristics, color tone and the like of this fixed image were evaluated. The evaluation results are shown in Tables 1 and 2.
Thereafter, a running evaluation of 100,000 sheets (11 inches × 15 inches / stock home paper NIP-1500LT, Kobayashi recording paper) was carried out using the image forming apparatus, and the subsequent developer charging characteristics, fixing properties and drawing characteristics. The color tone was evaluated.

By comparing the evaluation results of Examples 1 to 10 and Comparative Examples 1 to 5, the following was found.
(1) The color tone gradually deteriorates as the content of diimonium salt in the toner increases. However, as can be seen from the comparison between Comparative Example 3 and Example 8, even when the total content of diimonium salt is the same, the color tone (color turbidity) is higher when the content ratio of aminium salt / diimonium salt is larger. ) Degradation is large. In order for the color tone deterioration to fall within an allowable range, the content ratio of aminium salt / dimonium salt needs to be 40 or less.
(2) Regarding the image density, charge retention characteristics (charge fluctuation due to the influence of the surrounding environment), charge stability (running), and fog, the diimonium salt ratio is rich in the content ratio of aminium salt / dimonium salt as well as the color tone. In the case, the performance deteriorates, and when the content ratio of dimonium salt is 50% or more, it is out of the practical acceptable range.
(3) Color toners that do not contain an aminium salt / diimonium salt are not fixed at all even after flash exposure, and the fixability of toners that contain only an aminium salt is also borderline. Even if the total amount is increased, it is the same. On the other hand, toners that also contain dimonium salts show better fixability than toners that contain aminium salts alone, and the content ratio of iminium salts / diimonium salts is more than 95: 5, and the content of dimonium salts is rich. In the range of fixing energy of 2.0 to 4.0 J / cm ² , good fixability is exhibited.

(Influence of anion species)
[Examples 11 to 12]
Two types of toner were used in the same manner as in Example 1 except that a dimonium nitrate compound (NIR-IM1; manufactured by Nippon Kayaku Co., Ltd., R ^{5 to} R ⁸ = C ₂ H ₅ ) was used as the infrared light absorber (B). Further, physical properties and various properties were evaluated in the same manner as in Example 1. Table 3 shows the blending ratio and evaluation results of each toner.

Among the experiments with similar execution conditions, the difference is that the anion of the aminium salt and the diimonium salt is different (Examples 11 and 12) and the anion is the same type (Examples 2 and 4). Comparing these experimental results, it was found that the use of the same kind of anion was excellent in the overall characteristics of the toner such as fixing property and color tone.
As a result of a factor investigation, it was confirmed that the maximum absorption value of the infrared absorption spectrum was slightly decreased and the absorption range was widened in the toner combining the aminium salt / diimonium salt of different anions. . It is presumed that a slight decrease in fixability and deterioration in color tone were caused by the decrease in the light absorption capability of the toner and the expansion of the absorption range toward the visible light. The inventors of the present invention have caused the phenomenon that the anion of the aminium salt and the anion of the diimonium salt are partially ion-exchanged in the toner production process, resulting in a shift in the absorption band. Presumed to have occurred.

  In order to avoid the above problems, it is desirable that the aminium salt and the diimonium salt used together in the toner have a common anion.

Example 13
(Full-color image formation / Part 1)
To examine the flash fixability when forming full-color images using three colors of yellow / magenta / cyan toners, the fixability and color tone of powder images composed of three layers of yellow, magenta, and cyan toners are examined. did. At this time, toners having different hiding powers by changing the particle size of the pigment in the toner are classified into three levels (with a hiding degree of 0 to 10; this level of toner is called “hiding degree α”). In the range of 10 to 15 degrees; this level of toner is referred to as “hiding degree β”), and in the range of 15 to 20 hiding degrees; this level of toner is referred to as “hiding degree γ”), By changing the blend ratio of the aminium salt / dimonium salt, toners having different infrared light absorption capabilities can be classified into three levels (the blend ratio of the aminium salt / dimonium salt is within the range of aminium salt / diimonium salt = 95; 05-85: 15). This level of toner is referred to as the ratio 1; 2 is the aminium salt / dimonium salt = 80; the range of 20 to 70:30; this level of toner is referred to as the ratio 2; Unsalted = 65; 35 to 60: 40 in the range of those; were prepared in total 27 kinds of toners referred to) the toner of this level the ratio 3. Table 4 shows the compositions of these toners.
The pigment particle size in the toner can be changed by creating a pigment master batch (adding a large amount of pigment into the binder resin and pre-kneading using a three-roll mill, etc. The pigment concentration high blended resin was prepared) and the processing time (preliminary mixing time) was adjusted to control the desired particle size.

Moreover, the following were used as the colorant of each color.
Yellow; Pigment Yellow 180 (P-HG; manufactured by Hoechst)
Magenta color; Pigment Red 122 (310; manufactured by Dainippon Ink & Chemicals, Inc.)
Cyan color; Pigment Blue 15: 3 (111; manufactured by Dainippon Ink & Chemicals, Inc.)

Three-layered powder image formation was carried out by the following method. First, using the tandem-type image forming apparatus shown in Example 1, development and transfer processes were performed for each development unit in three development units to form a toner image in which three toner powder images were laminated on a recording medium. . Thereafter, flash light irradiation was performed in the same manner as in Example 1, the laminated toner layers were fixed at once, and the color tone and fixability of each toner combination were evaluated. The flash irradiation energy was 4.0 J / cm ² .

  First, as a basic study, only 13-U toner, 13-X toner, and 13-a toner (that is, a highly transparent toner group) that is a toner group that limits the toner color to yellow and has “hiding power α” are used. The results of evaluation using the results are shown in Table 5.

From this result, the following was found.
(1) A group having a fixing level of “excellent” and “good” is evaluated in a group in which the toner constituting the lower layer (the toner layer closest to the recording medium) has an aminium salt / diimonium salt ratio of 65; 35 to 60: 40, that is, all combinations in which the toner of IR agent blend ratio level 3 is the lower layer, and the ratio of aminium salt / diimonium salt is in the range of 80; 20 to 70:30, The toner with the IR agent blend ratio level of 2 is a part of the lower layer combination. From the group in which a toner having an aminium salt / diimonium salt ratio of 95; 05 to 85:15 is developed in the lower layer, that is, a combination in which a toner having an IR agent blend ratio level of 1 is the lower layer, the fixing level is “excellent” and “ There is no evaluation result of “good”. As a result, although the fixing level improves as the number of toner layers having a higher dimonium salt ratio increases, the ratio of the dimonium salt in the lower toner layer is higher when the total dimonium salt ratio in each toner layer is the same. The fixing property is improved by forming the toner layer.

(2) The toner group for which the color tone level is judged as “excellent” is the toner in the upper, middle and lower three layers in the range of aminium salt / diimonium salt ratio 95; 05 to 85:15, ie, IR agent blend ratio This is only one example of using level 1 toner in all layers. The evaluation result of the color tone level does not correlate with the toner layer stacking order, and the total amount of dimonium salt contained in the toner of the three-layer toner tar is large (as the toner having a high dimonium salt content ratio is used in many layers). ) Deteriorates as much. The combination within the practical allowable range is a toner group in which the sum of the level values of the IR agent blend ratio levels of each toner layer is a combination of 5 or less.

  Based on the analysis of the above results, a combination that has a good balance in color tone and fixing performance is expressed by the level value of the IR agent blend ratio level, from the upper layer (side closer to the fixing device) to the lower layer (on the recording medium). The example in which the toner layers are arranged in the order of 1-2-3 in the order of the contact side) is most preferable, and then the order of 1-3-2 is preferable.

  Although details are omitted, according to the study by the present inventors, although not as remarkable as the case of the yellow toner, the relationship between the IR agent blend ratio level, the fixing property, and the color tone also in the evaluation with the cyan toner and the magenta toner. The same tendency was confirmed in.

Next, as a means for improving the color tone, the relationship with the toner hiding degree was investigated. Using a matrix of yellow toner (toner 13-S to toner 13-a) in which the degree of hiding and the aminium salt / diimonium salt ratio (IR agent blend ratio level) were changed, the aminium salt / diimonium salt ratio (IR agent blend) The relationship between the specific level 1 to 3), the degree of hiding (α to γ), the color tone and the fixing property was determined.
In this experiment, after developing and transferring three times with the toner to be tested, a powder image of three toner layers is formed, and then an evaluation image is collected by flash fixing, and the color tone and the degree of concealment are measured. The relationship was investigated. The results are shown in Table 6.

As a result, the following was found.
(1) There is no difference in toner fixability depending on the degree of toner concealment.
(2) Even in a toner having an aminium salt / diimonium salt ratio (IR agent blend ratio level) of 2 levels, a good color tone can be obtained as long as the toner has a concealment degree of β level or more, and an aminium salt / diimonium salt ratio (IR agent) Even when the blend ratio level is 3 levels, a good color tone can be maintained by setting the toner hiding degree to the γ level or higher.

The findings were verified with full-color images consisting of yellow, magenta, and cyan. The order of toner layer formation is the order of 1-2-3 from the upper toner layer at the aminium salt / diimonium salt ratio (IR agent blend ratio level), which is the recommended order for the present invention derived from the above study, 1- The order of development was set so that the toner layer was formed in two forms in the order of 3-2, and the influence on the fixability and color tone by changing the concealment degree of each toner constituting the toner layer was investigated. At this time, in a toner having an aminium salt / diimonium salt ratio (IR agent blend ratio level) of 1 level, a concealment level α (that is, 13-C toner, 13-L toner, 13-U toner) and 2 In the case of a level toner, β (that is, 13-E toner, 13-N toner, 13-W toner), and in the case of a 3-level toner, a combination of toners that becomes γ (that is, 13-I toner, 13-R toner, 13-toner) a toner) was used.
For comparison purposes, the same evaluation was performed in the order of 3-2-1 from the upper toner layer to the IR agent blend ratio level. Also in this comparative example, a toner having a combination of the same IR agent blend ratio level and hiding degree was used.

  In the evaluation, yellow, cyan, magenta, green, blue, and red color tones are printed for each toner combination and development sequence, and the results of printing these six colors are measured, and the toner combinations and development sequence are measured. The gamut area that can be expressed was investigated. Specifically, based on ISO / CD13655, the CIE L *, a *, and b * of each color-fixed image were measured using a color difference meter 938 Spectrometer (measurement light source CIE-D65) manufactured by X-Rite. The area surrounded by the color values of the six color toners measured in this way is the color gamut area. The quality of each toner combination and development order was judged by evaluating the area of the color gamut of these six colors, the fixability, and the state of voids.

As a result, the following was found.
(1) When a toner having a high concealment degree (particularly, a concealment degree γ level) is used as the toner used for the upper layer and the middle layer, the color tone of the toner layer below the layer is masked, and the color reproduction range is distorted (for example, the concealment degree). If the development sequence is configured so that the yellow toner of γ becomes the upper toner layer, among the above six colors, the color tone of green and red is yellowish, and the color gamut represented by these toners shifts to the yellow side. The color gamut that can be expressed by a combination of these toners becomes narrower).
(2) Therefore, the upper layer has an aminium salt / diimonium salt ratio of 1 level, the concealment degree is α level, the intermediate layer has an aminium salt / diimonium salt ratio of 2 level, the concealment degree is β level, and the lower layer has an aminium salt / diimonium salt ratio. By setting the toner and the image forming method so that toners having three levels and a concealment degree of γ level are stacked, it is possible to balance the relationship between the fixing property and the color tone in a trade-off relationship at the most excellent level.
(3) If the relationship of (2) is maintained, no significant difference will occur in the color reproduction range of the image, regardless of the color tone of the upper, middle and lower toner colors.

  According to the present invention, the photofixability is good, and it is possible to extend the life and stability of the environment by stabilizing the charge. It is possible to provide a color toner for image formation that can maintain the development characteristics and has little influence on the hue by the infrared absorber.

It is a figure which shows an example of the image forming apparatus used for this invention. It is a figure which shows the emission spectrum of a xenon light source.

Explanation of symbols

1a, 1b, 1c, 1d Charging means 2a, 2b, 2c, 2d Exposure means 3a, 3b, 4c, 3d Latent image carrier (photoconductor)
4a, 4b, 4c, 4d Developing means 10 Intermediate transfer member (transferred member)
20 Black developing unit 30 Cyan developing unit 40 Magenta developing unit 50 Yellow developing units 60a, 60b, 60c, 60d First transfer means (transfer roller)
70 Second transfer means (transfer roller)
71 Primary transfer voltage supply means 72 Secondary transfer voltage supply means 80 Light fixing means 90 Cleaning means 200 Recording medium

Claims (7)

It contains both an aminium salt compound represented by the following general formula (I) and a diimonium salt compound represented by the following general formula (II), and the weight ratio of the aminium salt compound to the diimonium salt compound ( A color toner for light fixing, wherein I: II) is 95: 5 to 60:40.

[Wherein, R ^{1 to} R ⁸ represent a hydrogen atom, an alkyl group, a substituted alkyl group, an alicyclic group, an alkenyl group, an aralkyl group or a substituted aralkyl group, and X ⁻ and Y ⁻ represent an anion. ] In the general formula (I) and formula (II), the anion X ^- and Y ^- is a color toner for optical fixing according to claim 1, wherein said to be identical.   A latent image forming step of forming an electrostatic latent image on the surface of the latent image carrier; a developing step of developing the electrostatic latent image formed on the surface of the latent image carrier with toner to form a toner image; A transfer step of transferring a toner image formed on the surface of the image bearing member to the surface of the transfer target, a fixing step of photofixing the toner image transferred to the surface of the transfer target on the surface of the recording medium, and forming an image; An image forming method comprising: the toner according to claim 1, wherein the toner is the toner according to claim 1. 4. The image forming method according to claim 3, wherein the image formation is performed using a plurality of toners, and the development is repeated n times sequentially using the second to nth toners after the development using the first toner. An image forming method that takes a sequential development batch photofixing process in which after a toner layer having 1 to n layers is sequentially formed from a toner layer that is close to the recording medium after the photothermographic processing, In a color toner for forming an arbitrary z-th toner layer, the ratio of aminium salt compound to diimonium salt compound a (z) [a = diimonium salt compound part by weight / (aminium salt compound part by weight + diimonium) (Parts by weight of salt-based compound)] satisfy the following relational expression.
a (z-1) ≧ a (z) 4. The image forming method according to claim 3, wherein the image formation is performed using a plurality of toners, and the development is repeated n times sequentially using the second to nth toners after the development using the first toner. An image forming method that takes a sequential development batch photofixing process in which after a toner layer having 1 to n layers is sequentially formed from a toner layer that is close to the recording medium after the photothermographic processing, An image forming method, wherein a toner colorant concealment degree C (z) satisfies the following relational expression in a color toner for forming an arbitrary z-th toner layer.
C (z-1) ≧ C (z) 4. The image forming method according to claim 3, wherein the image formation is performed using a plurality of toners, and the development is repeated n times sequentially using the second to nth toners after the development using the first toner. An image forming method that takes a sequential development batch photofixing process in which after a toner layer having 1 to n layers is sequentially formed from a toner layer that is close to the recording medium after the photothermographic processing, In a color toner for forming an arbitrary z-th toner layer, the ratio of aminium salt compound to diimonium salt compound a (z) [a = diimonium salt compound part by weight / (aminium salt compound part by weight + diimonium) Salt-based compound parts by weight)] and toner colorant hiding degree C (z) satisfy the following relational expression.
a (z-1) ≧ a (z)
C (z-1) ≧ C (z)   A latent image carrier, charging means for charging the surface of the latent image carrier, latent image forming means for forming a latent image on the surface of the charged latent image carrier, and a developer containing toner are accommodated therein. A developing unit that develops the latent image by the developer layer formed on the surface of the developer carrying member and forms a toner image on the surface of the latent image carrying member; and a transfer unit that transfers the toner image to a recording medium And a fixing unit that optically fixes the toner image transferred to the surface of the recording medium and forms an image, wherein the toner is the toner according to claim 1 or 2. Image forming apparatus.

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