JP2000155439A - Near infrared absorber for electrophotographic toner and electrophotographic toner containing this absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance absorption of light energy and a conversion efficiency of light energy to heat energy and fixing strength by flash fixation by using the electrophotographic toner containing a specified near infrared absorber. SOLUTION: The electrophotographic toner contains the near infrared absorber represented by the formula in which each of R1-R20 is, independently, an H or halogen atom or an optionally substituted alkyl or such alkoxy, such aryl, such aryloxy, alkyl amino, dialkylamino, arylamino, or diarylamino group; and M is a metal atom. A preferable one of R1-R20 is an H atom or a straight or branched alkyl or alkoxy group and a preferable metal represented by M is Ni, Pd, Pt, Cu, and the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a near-infrared absorber for electrophotographic toner used for developing an electrostatic latent image in electrophotography, and an electrophotographic toner containing the near-infrared absorber. More specifically, the present invention relates to a near-infrared absorbing agent for an electrophotographic toner and an electrophotographic toner which give a fixed image having particularly high fixing strength in a flash fixing method.

[0002]

2. Description of the Related Art Conventionally, electrophotography uses a photoconductive insulator, applies a uniform electrostatic charge to the photoconductive insulator by corona discharge or the like, and uses various means to form the photoconductive insulator. Forming an electrostatic latent image by irradiating a light image on the insulator,
Next, the latent image is developed and visualized using toner, and if necessary, a toner image is transferred onto a recording medium such as paper, and then the recording medium is pressed, heated, irradiated with solvent vapor, light, or the like. A copy is obtained by fixing the toner image thereon. The toner image transferred onto the recording medium adheres to the recording medium in a powder state to form an image. For example, if the image is rubbed with a finger, the image is destroyed. In order to fix a toner image on a recording medium, it is necessary to melt the toner and fix it on the recording medium. As a method therefor, there are means such as the above-mentioned pressurization, heating, irradiation of solvent vapor, light and the like. Among them, flash fixing, which is a light fixing method, is performed, for example, by flashing (800 to 1000 nm) of a discharge tube such as a xenon flash lamp.
This method has the following characteristics.

In other words, since non-contact fixing is used, the resolution of an image during development is not degraded, there is no waiting time after turning on the power, quick start is possible, and the recording medium is jammed in the fixing unit due to the system down. Does not ignite, and it can be fixed regardless of the material and thickness of the recording medium, such as glued paper, preprinted paper, and paper of different thickness. In this flash fixing method, when a flash of a discharge tube of a xenon flash lamp is irradiated, the toner absorbs the light energy of the flash, the temperature rises, and the toner is softened and melted, and adheres to and penetrates the recording medium. After the end of the flash, the temperature drops and solidifies to form a fixed image, which is fixed, fixed on the recording medium, and the collapse of the image is eliminated.

In this flash fixing method, in the conventional color toner, although the colorant has absorption in the visible region, absorption in the near infrared region is weak, conversion efficiency into heat energy is poor, and sufficient fixing cannot be obtained. . Further, in the black toner, although a black color material such as carbon black as a colorant has an absorbing ability also in a near-infrared region, the conversion efficiency into heat energy is not sufficient, and various problems are caused. have.

One of the important characteristics in fixing a flash fixing toner is that the toner needs to efficiently absorb flash light and convert light energy into heat energy. Such absorption of light energy and light energy /
In order to obtain properties relating to thermal energy conversion, toners have been proposed in which carbon black or the like of an inorganic compound or a near-infrared absorbing dye of an organic compound is added and dispersed.
For example, in JP-A-58-102247, a cyanine dye is disclosed, and in JP-A-60-57858, a benzenedithiol-based metal complex dye forming an ion pair is disclosed in JP-A-7-191.
No. 492 discloses an aminium-based dye.

The dyes disclosed in these publications have poor heat resistance of the dyes themselves. For example, the dyes are thermally decomposed and melted and kneaded with a binder resin to produce a toner, resulting in a decrease in near-infrared absorptivity. And various problems such as insufficient light-to-heat conversion, and a satisfactory fixing strength has not been achieved. Other near-infrared absorbing dyes have also been proposed, but some dyes are colored because they themselves absorb in the visible region. There were problems that recording could not be obtained and that the photothermal conversion was not sufficient, so that the fixing strength was poor.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to improve the absorption efficiency of light energy and the conversion efficiency of light energy / heat energy, and to enhance the fixing strength by flash fixing and to improve the fixing strength of electrophotographic toner. An object of the present invention is to provide an electrophotographic toner containing the near infrared absorbing agent.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, a specific near-infrared absorbing agent is used as a near-infrared absorbing agent for an electrophotographic toner. Have excellent properties of light energy absorption and light energy / heat energy conversion efficiency,
The present invention has been completed. That is, the present invention relates to a near-infrared absorber for an electrophotographic toner represented by the following general formula (1) (Formula 2), and further relates to an electrophotographic toner containing the near-infrared absorber. It is about.

[0009]

Embedded image (Wherein, R _{1 to} R ₂₀ each independently represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, Represents an aryloxy group, an alkylamino group, a dialkylamino group, an arylamino group, or a diarylamino group, and M represents a metal atom.)

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The near-infrared absorbing agent for an electrophotographic toner of the present invention is a near-infrared absorbing agent represented by the general formula (1). In the general formula (1), R _{1 to} R ₂₀ each independently represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, Represents an aryloxy group, an alkylamino group, a dialkylamino group, an arylamino group, or a diarylamino group which may be substituted, and M is a metal atom.

Hereinafter, the present invention will be described in detail.
It is not limited to these. In R _{1 to} R ₂₀ , the alkyl group which may be substituted includes a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, a sec-butyl group and a tert. -Butyl group, n-pentyl group, iso-pentyl group, neopentyl group, n-hexyl group, iso-
Hexyl group, sec-hexyl group, n-heptyl group, i
alkyl groups such as so-heptyl group, sec-heptyl group, n-octyl group and 2-ethylhexyl group; halogenoalkyl groups such as chloroethyl group, bromoethyl group and trifluoromethyl group; methoxymethyl group, methoxyethyl group and ethoxyethyl An alkoxyalkyl group such as a group, a propoxyethyl group, a butoxyethyl group; a hydroxyalkyl group such as a hydroxyethyl group or a hydroxypropyl group;
Examples thereof include hydroxypolyether groups such as hydroxyethoxyethyl group and hydroxyethoxyethoxyethyl group; and alkoxypolyether groups such as methoxyethoxyethyl group, ethoxyethoxyethyl group, propoxyethoxyethyl group and butoxyethoxyethyl group.

The optionally substituted alkoxy group includes methoxy, ethoxy, n-propoxy, is
o-propoxy group, n-butoxy group, iso-butoxy group, tert-butoxy group, n-pentyloxy group, i
so-pentyloxy group, neopentyloxy group, n-
Examples include an alkoxy group such as a hexyloxy group, an iso-hexyloxy group, an n-heptyloxy group, an iso-heptyloxy group, an n-octyloxy group, and a 2-ethylhexyloxy group.

The aryl group which may be substituted includes a phenyl group, a naphthyl group, a 4-methylphenyl group,
4-ethylphenyl group, 4-propylphenyl group, 4-
tert-butylphenyl group, 4-methoxyphenyl group, 4-ethoxyphenyl group, 4-chlorophenyl group,
4-bromophenyl group, 2-methylphenyl group, 2-ethylphenyl group, 2-propylphenyl group, 2-t-butylphenyl group, 2-methoxyphenyl group, 2-ethoxyphenylthio group, 2-hydroxyphenylthio Group, 2
-Chlorophenyl group, 2-bromophenyl group and the like.

The aryloxy group which may be substituted includes a phenoxy group, a naphthyloxy group, a 4-methylphenoxy group, a 4-ethylphenoxy group, a 4-propylphenoxy group, a 4-tert-butylphenoxy group,
-Methoxyphenoxy group, 4-ethoxyphenoxy group,
4-chlorophenoxy group, 4-bromophenoxy group, 2
-Methylphenoxy group, 2-ethylphenoxy group, 2-
Propylphenoxy group, 2-t-butylphenoxy group,
Examples thereof include a 2-methoxyphenoxy group.

An optionally substituted alkylamino group,
Alternatively, in the optionally substituted dialkylamino group, examples of the optionally substituted alkyl group include the above-described alkyl groups, and an optionally substituted arylamino group or an optionally substituted In the diarylamino group, examples of the optionally substituted aryl group include the aforementioned aryl groups. In particular,
As R _{1 to} R ₂₀ , a hydrogen atom, a linear or branched alkyl group, or an alkoxy group is preferable. Examples of the metal represented by M include Ni, Pd, Pt, and Cu.

The near-infrared absorbing agent represented by the general formula (1) of the present invention can be produced, for example, by the method described in JP-A-2-264787, but is not limited thereto. . Specifically, in a solvent, a benzoin derivative represented by the following general formula (2) and a sulfur compound such as diphosphorus pentasulfide (1 to 5 molar ratio with respect to the benzoin derivative) are dissolved in a solvent (for example, N, N-dimethylimidazolidinone is preferred), and reacted at 50 to 160 ° C.
Subsequently, a metal compound (0.4 to the benzoin derivative)
To 2 mol ratio) at 10 to 160 ° C. The reaction scheme is as follows.

[0017]

Embedded image (In the above formula, R1 to R20 and M are the same as those in the general formula (1), and X represents a halogen atom.)

Next, the electrophotographic toner of the present invention will be described. The toner for electrophotography of the present invention comprises at least
It comprises a binder resin, a near-infrared absorbing agent represented by the general formula (1) of the present invention, a coloring agent, and other additives. In the electrophotographic toner of the present invention, the amount of the near-infrared absorbing agent of the present invention varies depending on the flash fixing strength of the toner and the like, but is preferably 0.01 to 50% by weight based on the binder resin.

The binder resin used in the electrophotographic toner of the present invention includes generally used polymer resins, for example, polystyrene, a copolymer of styrene and acrylate or methacrylate, a polyester resin, Epoxy resins, polyamide resins, phenolic resins, hydrocarbon resins, petroleum resins, and the like can be used, and these may be used alone or in combination, and are not limited to these resins. Further, all of these resins have extremely small absorption of light in the visible and near-infrared regions.

The colorant used in the electrophotographic toner of the present invention includes commonly used pigments and dyes. For example, in the case of a black toner, carbon black, a nigrosine dye, etc. may be mentioned. And xanthene dyes, phthalocyanine dyes, triphenylmethane dyes, and the like, but are not limited to these resins. The amount of these used is preferably 0.1 to 50 parts by weight based on 100 parts by weight of the binder resin.

The electrophotographic toner may further contain various plasticizers, release agents, ultraviolet absorbers, etc. for the purpose of adjusting charge control agents, fluidity modifiers, thermal characteristics, physical characteristics, etc., if necessary. Can also be added. Examples of the charge control agent include a positive charge control agent such as a quaternary ammonium salt, a guanamine derivative, an amine-modified styrene-acrylic resin, and a benzothiazole derivative. Metal salicylic acid salts, metal complexes of dicarboxylic acids, and the like can be mentioned, whereby the charge can be adjusted. The amount of addition is determined in consideration of conditions such as the chargeability of the resin, the content of the colorant, and the chargeability of other additives. 5 parts by weight are preferred. Further, as the fluidity modifier, for example, colloidal silica may be mentioned, and the amount of the additive may be 0.0 to 1 part by weight of the electrophotographic toner.
It is preferably from 0.01 to 5 parts by weight. Further, a polyolefin-based wax and a natural wax can be used in combination.

The toner can be manufactured by a known method. For example, a binder resin, a coloring agent, a near-infrared absorbing agent, and a charge adjusting agent are melt-kneaded by a kneader for press, a roll mill, an extruder, and the like, uniformly dispersed, and crushed,
Finely pulverized by a jet mill or the like, and classified by a classifier to obtain a desired toner. The toner manufactured in this manner is a known heat roll, pressure fixing, solvent fixing,
Any fixing method such as light fixing can be used, but the effect is great when used in light fixing, particularly in flash fixing method.

The electrophotographic toner of the present invention can be mixed with a carrier and used as a two-component developer. Examples of the carrier include a ferrite powder, a fine powder magnetic substance dispersed in a resin, and a resin-coated carrier in which the carrier surface is coated with a resin.

[0024]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto. In the examples, "parts" indicates parts by weight. Example 1 Synthesis Example of Near-Infrared Absorber 5 parts of benzoin and 7.5 parts of diphosphorus pentasulfide were added to 35 parts of N, N-dimethylimidazolidinone, and the mixture was added at 100 ° C.
Allowed to react for hours. Subsequently, nickel chloride hexahydrate 2.8
A solution prepared by dissolving 10 parts in 10 parts of water was added dropwise, and reacted at 90 ° C. for 2 hours. After completion of the reaction, the mixture was cooled to room temperature, discharged into 150 parts of ethanol, filtered, washed and dried to obtain 5 parts of the following near-infrared absorbent (a) (formula 4).

[0025]

Embedded image

Method for Preparing Toner 95 parts of a binder resin (styrene-acrylic acid copolymer; Hymer TB-1000F, manufactured by Sanyo Chemical Co., Ltd.), 10 parts of the near-infrared absorbing agent (a), and C.I. I. Pigm
5 parts of ent Blue 15: 1 (FASTOGEN Blue 5050, manufactured by Dainippon Ink and Chemicals, Inc.) were coarsely pulverized by a ball mill and then finely pulverized by a jet mill pulverizer. Further classifying and selecting 1-20 μm, 1
Carrier iron (made by Nippon Iron Powder, EFV250 / 4)
00) 90 parts were uniformly mixed to obtain a blue toner. This blue toner was set in a commercial copying machine, and after recording an unfixed image, flash fixing was performed using a xenon flash lamp. Using the cellophane tape (Sumitomo 3M, Scotch mending tape),
The residual ratio of the recorded image after the tape was peeled was calculated by the following formula, and evaluated as the fixing strength. Residual rate (%) = image density after tape peeling / image density before tape peeling × 100 As a result, the residual rate was 90%, and the fixing strength was good.

Example 2 A toner was prepared in the same manner as in Example 1, except that the near-infrared absorbing agent (a) was replaced by the following near-infrared absorbing agent (b) (formula 5). . Using the toner thus produced, a recorded image was obtained in the same manner as in Example 1, and a peel test was performed on this image in the same manner as in Example 1. As a result, the residual ratio was 91%, and the fixing strength was 91%. It was good.

[0028]

Embedded image

Example 3 Binder resin (polyester resin; NE-215, manufactured by Kao Corporation)
0 ((ART-2009) 1320 parts, near infrared ray absorbent (a) 30 parts, colorant CI Pigment Y)
yellow 81 (manufactured by Dainippon Ink and Chemicals, FAS
TOGEN SUPER YELLOW GRO) 80
Part, charge adjusting agent (manufactured by Nippon Kayaku, Kayacharge N-4) 2
0 parts, wax (Viscol 550P, Sanyo Chemical) 5
After melt-kneading 0 parts, the mixture was roughly pulverized by a ball mill and then finely pulverized by a jet mill pulverizer. 1-20
μm was selected to prepare a toner. Next, a ferrite carrier (KBN-100, manufactured by Hitachi Metals, Ltd.) was uniformly mixed to obtain a yellow toner. Using the yellow toner thus produced, a recorded image was obtained in the same manner as in Example 1, and the image was subjected to a peeling test in the same manner as in Example 1. As a result, the residual ratio was 87%, and the fixing strength was 87%. Was good.

Example 4 95 parts of a binder resin (epoxy resin; Epicron 1191, manufactured by Dainippon Ink and Chemicals, Inc.)
0 parts, colorant (LionolRed, manufactured by Toyo Ink Co., Ltd.)
After melt-kneading 5 parts of CP-A) and 1 part of a charge controlling agent (manufactured by Orient Chemical Industries, Inc., Bontron P-51), the mixture was coarsely pulverized by a ball mill and then finely pulverized by a jet mill pulverizer. After further classification, 1 to 20 μm was selected to prepare a toner. Next, a ferrite carrier (KBN- manufactured by Hitachi Metals, Ltd.)
100) to obtain a red toner. Using the red toner thus produced, a recorded image was obtained in the same manner as in Example 1, and a peel test was performed on this image in the same manner as in Example 1. As a result, the residual ratio was 90%, and the fixing strength was 90%. Was good.

Examples 5 to 30 In the toner preparation method shown in Example 1, instead of the near infrared absorbing agent (a), R _{1 to} R in the general formula (1) were used.
_20. Various toners were prepared in the same manner except that various near-infrared absorbing agents in which M was a substituent and a metal shown in Table 1 (Tables 1 and 2) were used. Example 1 using these toners
Recording images were obtained in the same manner as in the above, and a peeling test was performed on these images. The results are shown in Table 1. In the peeling test, recorded images obtained using various toners containing the near-infrared absorbing agent represented by the general formula (1) all had a high residual ratio and were excellent in fixing strength in flash fixing. . In the table, in the evaluation of fixability, those having a residual ratio of 80% or more are indicated by “○”.

[0032]

[Table 1]

[0033]

[Table 2]

Comparative Example A toner was prepared in the same manner as in Example 1 except that the following compound (c) (Formula 6) was used in place of the near-infrared absorbing agent (a) in the toner preparation method shown in Example 1. Was prepared. Using this toner, a recorded image was obtained in the same manner as in Example 1, and a peeling test was performed on this image to evaluate the fixability. As a result, the residual ratio of the recorded image in the tape peeling test was 30% or less, and the fixing strength was poor and the fixing was insufficient as compared with the toner using the near-infrared absorbing agent of the present invention.

[0035]

Embedded image

[0036]

The near-infrared absorbent for toner for electrophotography of the present invention has excellent characteristics of light energy absorption and light energy / heat energy conversion efficiency, and is an electrophotographic recording system, especially a flash fixing system. It can be suitably used for the toner used in the above.

Claims (5)

[Claims] 1. A near-infrared absorbent for toner for electrophotography represented by the following general formula (1) (formula 1). Embedded image (Wherein, R _{1 to} R ₂₀ each independently represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, Represents an aryloxy group, an alkylamino group, a dialkylamino group, an arylamino group, or a diarylamino group, and M represents a metal atom.) 2. The near-infrared absorbent for an electrophotographic toner according to claim 1, wherein R _{1 to} R ₂₀ are each independently a hydrogen atom, an alkyl group or an alkoxy group. 3. The near-infrared absorbing agent for an electrophotographic toner according to claim 1, wherein M is any one of Ni, Pd, Pt, and Cu. 4. An electrophotographic toner comprising the near-infrared absorbing agent for an electrophotographic toner according to claim 1. 5. The electrophotographic toner according to claim 4, wherein the toner is for flash fixing electrophotography.