JP2005099295A - White toner for non-contact fixing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a white toner for non-contact heating fixing which is not tinged with color even when adding an infrared absorber. <P>SOLUTION: The white toner for non-contact fixing contains at least a white system colorant, a binder resin holding the colorant, an infrared absorber of absorbing infrared rays from a non-contact heater and an achromatic agent which is in a complementary color relation with the infrared absorber. Therein, such a white toner that L* value in the L*a*b* color system is ≥85 and c* value stipulated by (a<SP>2</SP>+b<SP>2</SP>)<SP>1/2</SP>is ≤10 is used. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a non-contact fixing white toner used in an image forming apparatus that uses a non-contact heat fixing device to fix toner onto a recording medium.

  In an image forming apparatus such as a copying machine or a printer, when fixing toner supplied onto a recording medium to the recording medium, various fixing apparatuses have been conventionally used, and one of them is an oven fixing apparatus or flash fixing. A non-contact heat fixing device such as a device has been used. The non-contact heat fixing device irradiates the toner supplied on the recording medium with heat or infrared rays, thereby heating the toner and fixing it to the recording medium.

Here, in the case of black toner, the toner particles contain carbon black or the like having high heat and infrared absorption properties, and the toner can be sufficiently fixed on the recording medium by the non-contact heating device as described above. . In the case of color toners other than black toner, heat and infrared absorbability is not sufficient, and an infrared absorbent is added to improve the fixability to a recording medium (for example, Patent Document 1).
JP 2002-156777 A

  On the other hand, white toner is used to form a white image using white toner on a chromatic color background, or to form a white image using white toner to increase the whiteness of a recording medium. . However, when an infrared absorber is added to the white toner for non-contact heat fixing, there is a problem that the white toner is colored by the color of the infrared absorber and cannot be achromatic. In particular, many infrared absorbers are green, and green is the wavelength region with the highest spectral sensitivity of the eyes. For this reason, even a slight coloring is extremely unpleasant.

  Accordingly, an object of the present invention is to provide a non-contact heat fixing white toner that does not become colored even when an infrared absorber is added.

The present inventors have found that the white toner can be achromatic by adding a color material having a reflection spectrum complementary to the reflection spectrum of the infrared absorber to the white toner, thereby completing the present invention. Is.
That is, the non-contact heat fixing white toner of the present invention is a non-contact fixing white toner used in an image forming apparatus for fixing a toner on a recording medium by a non-contact heating device, and the white toner is at least A white colorant, a binder resin that holds the colorant, an infrared absorber that absorbs infrared rays from the non-contact heating device, and a coloring agent that is complementary to the infrared absorber. The L ^* value in the L ^* a ^* b ^* color system is 85 or more and the c ^* value defined by (a ² + b ² ) ^1/2 is 10 or less.

Since the white toner of the present invention contains an achromatic agent having a complementary color relationship with the infrared absorber, the white toner is not colored even after being fixed on the recording medium, so that L ^* a ^* b ^* color specification It is possible to form a high-quality white toner image in which the L ^* value in the system is 85 or more and the c ^* value defined by (a ² + b ² ) ^1/2 is 10 or less.
^{Here, L * a * b * L} * value in ^(Elster Esuta Bee Star) color system represents a lightness, refers to a measure of the relative brightness of color and brightness. a ^* and b ^* both represent hue and saturation. Hue is a measure of color attributes such as red, yellow, green, blue, purple, etc., and saturation is a measure of the vividness of a color expressed by a distance from an achromatic color of equal brightness. Further, the c ^* value defined by (a ² + b ² ) ^1/2 represents saturation.
The whiteness is the degree of whiteness of the surface color, and can be measured, for example, by a method defined in JIS Z 8715.

  Further, since it has the above brightness and saturation, it is considered that the color reproducibility when white toner and other color toners are superimposed is improved. The color reproducibility is a characteristic that can reproduce color characteristics such as brightness and saturation of a copy color as it is when a desired color is color-copied. When preparing the color, it is said that it has the characteristic that a superposed color can be prepared without drastically reducing the saturation and lightness of a single color.

  Further, the white toner of the present invention can be suitably used for mark fabrics. Mark fabrics used for clothing numbers and logos have a portion with good flatness on the surface in order to obtain gloss. This flatness is preferable since there is no image distortion during development and transfer when printing on a fabric by electrophotography or the like. However, with respect to the fixability, since the surface of the fabric is smooth, the heat roll fixing device tends to stick the toner and easily cause a fixing failure. Further, if the mark fabric is passed between the hot rolls, the heat-welding adhesive layer may be excessively heated and the protective sheet may be peeled off. Therefore, in order to improve productivity, it is necessary to use a non-contact heat fixing device.

  The white toner of the present invention preferably uses a flash fixing device as a non-contact fixing device. This is because the flash fixing device can efficiently generate infrared rays.

  Since the non-contact heat fixing white toner of the present invention contains an achromatizing agent complementary to the infrared absorber, it is possible to provide an achromatic, excellent fixing property and high-quality white toner. Can do.

  Embodiments of the present invention will be described below with reference to the drawings.

  The white toner according to the present embodiment includes at least a white colorant, a binder resin that holds the colorant, an infrared absorber that absorbs infrared rays from a non-contact heating device, and the infrared absorber and complementary color. It is composed of a neutralizing agent that has a relationship.

  Examples of white colorants used in the white toner of the present embodiment include titanium dioxide, zinc white, lead white, lead sulfate, lithopone, zinc sulfide, antimony oxide, lead zinc white, basic sulfate, lead silicate, White pigments composed of zircon oxide, barium metaborate, patchonson white, manganese white, tin oxide, tungsten white, calcium leadate, or a mixture thereof can be used, and titanium dioxide is particularly preferable.

  Here, the titanium dioxide may be produced by any method such as sulfuric acid method, hydrochloric acid method, gas phase method, etc., and any crystal form of anatase type, rutile type or brookite type can be used. It is. As the white pigment, one having a particle size of 0.05 μm to 0.5 μm, preferably 0.1 μm to 0.4 μm is used. If the particle size is less than 0.05 μm, sufficient hiding power cannot be obtained. On the other hand, if it is larger than 0.5 μm, the binding property with the binder resin is inferior, so that toner scattering and the accompanying toner fog occur.

  Also, conventionally known binder resins such as styrene-acrylic resins, epoxy resins, and polyester resins can be used for the white toner of the present embodiment.

  Moreover, a well-known infrared absorber can be used for the infrared absorber used for this Embodiment. For example, cyanine compounds, merocyanine compounds, benzenethiol metal complexes, mercaptophenol metal complexes, aromatic diamine metal complexes, diimonium compounds, aminium compounds, nickel complex compounds, phthalocyanine compounds, anthraquinone compounds, naphthalocyanine compounds, etc. Specifically, a metal complex infrared absorber (Mitsui Chemical Co., Ltd .: SIR-130, SIR132), bis (dithiobenzyl) nickel (Midori Chemical Co., Ltd .: MIR-101), bis [1 , 2-Bis (p-methoxyphenyl) -1,2-ethylenedithiolate] nickel (manufactured by Midori Chemical Co., Ltd .: MIR-102), tetra-n-butylammonium bis (cis-1,2-diphenyl-1,2) -Ethylene dithiolate) Nickel (Midori Chemical Co., Ltd .: IR-1011), tetra-n-butylammonium bis [1,2-bis (p-methoxyphenyl) -1,2-ethylenedithiolate] nickel (manufactured by Midori Chemical Co .: MIR-1021), bis (4-tert -1,2-butyl-1,2-dithiophenolate) nickel-tetra-n-butylammonium (manufactured by Sumitomo Seika Chemicals Co., Ltd .: BBDT-NI), cyanine infrared absorber (manufactured by Fuji Photo Film Co., Ltd .: IRF-106 , IRF-107), inorganic salt-based infrared absorbers (made by Teikoku Chemical Industry Co., Ltd .: NIR-AM1), imonium compounds (made by Nippon Carlit Co., Ltd .: CIR-1080, CIR-1081), aminium compounds (produced by Nippon Carlit Co., Ltd .: CIR) -960, CIR-961), anthraquinone compound (manufactured by Nippon Kayaku Co., Ltd .: IR-750), aminium compound Nippon Kayaku Co., Ltd .: IRG-002, IRG-003), polymethine compounds (Nippon Kayaku Co., Ltd .: IR-820B), diimonium compounds (Nippon Kayaku Co., Ltd .: IRG-022, IRG-023), dianine A compound (Nippon Kayaku Co., Ltd .: CY-2, CY-4, CY-9), soluble phthalocyanine (Nippon Shokubai Co., Ltd .: TX-305A), etc. can be used.

  The infrared absorber is preferably selected according to the light source used in the heat fixing apparatus. For example, when a xenon lamp is used as the light source, it is preferable to use a compound having an absorption band at 830 to 980 nm, for example, an aminium compound. Moreover, when using a halogen lamp for a light source, it is preferable to use the compound which has an absorption band in 850-1250 nm, for example, a diimonium type compound can be mentioned.

  The addition amount of the infrared absorber is 0.1 to 1.5 parts by weight, more preferably 0.3 to 0.8 parts by weight with respect to 100 parts by weight of the toner. If the amount is less than 0.1 parts by weight, the fixing property is insufficient, and if it is more than 1.5 parts by weight, infrared rays are not absorbed efficiently.

Next, the achromatic agent used in the present embodiment will be described. As the achromatizing agent, a color material having a complementary color relationship with the above infrared absorber can be appropriately selected. Specifically, a color material having a reflection spectrum that is complementary to the reflection spectrum of the infrared absorber is selected.
For example, C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 83, 180, C.I. I. Yellow pigments such as vat yellow 1, 3, 20; I. Yellow dyes such as Solvent Yellow 79 and 162 can be used.

  Further, as a magenta color material, for example, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 49, 50, 51, 52, 53, 54, 55, 57, 58, 60, 63, 64, 68, 81, 83, 87, 88, 89, 90, 112, 114, 122, 123, 163, 184, 185, 202, 206, 207, 209, magenta pigments such as Pigment Violet 19, and C.I. I. Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 81, 82, 83, 84, 100, 109, 121, C.I. I. Disper thread 9, C.I. I. Magenta dyes such as Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, etc. Can be used.

  Further, as a cyan color material, for example, C.I. I. Examples of red colorants such as cyan pigments such as CI Pigment Blue 2, 3, 15, 16, and 17 include Bengala, Cadmium Red, Lead Tan, Mercury Sulfide, Cadmium, Permanent Red 4R, Resol Red, Pyrazolone Red, and Watching Red. , Calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B, and the like.

  As the green color material, for example, chrome green, chrome oxide, pigment green B, micalite green lake, final yellow green G, or the like can be used.

  As the blue color material, for example, bitumen, cobalt blue, alkali blue lake, phthalocyanine blue, metal-free phthalocyanine blue, partially chlorinated phthalocyanine blue, first sky blue, indanthrene blue BC, and the like can be used.

The addition amount of the achromatic ^agents, L ^* a * ^{b * L *} value 85 or more at the color system, and as ^{c *} value is 10 or less, more preferably ^{L *} value of 90 or more, and c ^* It can select suitably according to the kind and quantity of the infrared absorber to be used so that a value may be 4 or less. In order to achieve achromatic color efficiently, the weight ratio is preferably 0.1 to 2 times, more preferably 0.1 to 1 times that of the infrared absorber.

  Further, in order to further improve the whiteness, a fluorescent whitening agent can be added to the toner. The fluorescent whitening agent is a colorless to pale yellow compound that absorbs in the near ultraviolet region and emits fluorescence from purple blue to blue (especially 400 to 500 nm), and can eliminate yellowishness by fluorescence. As an example of the fluorescent whitening agent, for example, a fluorescent whitening agent leuco plastic EGM manufactured by Clariant Co., etc. can be used.

For the production of the white toner of the present embodiment, a conventional kneading-pulverizing method or wet granulation method can be used.
In the case of the kneading-pulverizing method, for example, white toner can be produced by the following method.
A: When a toner is granulated from a white pigment and a binder resin, an infrared absorber and a neutralizing agent are internally added.
B: After the toner is granulated from the white pigment and the binder resin, an infrared absorber or an achromatic agent is externally added so as to be fixed to the toner particle surface using a surface modification device.
Note that it is not always necessary to add the infrared absorber and the achromatic agent together, but it is also possible to add them separately such that one is internally added and the other is externally added.

Here, when the white pigment is kneaded and pulverized with the binder resin, the white pigment is added in an amount of 15 to 60 parts by weight, preferably 20 to 50 parts by weight with respect to 100 parts by weight of the binder resin. When the white pigment exceeds 60 parts by weight, the binding property and dispersibility of the pigment and the binder resin are deteriorated. Even if surface modification is performed in a later step, moisture resistance deterioration, toner scattering, fogging, fixing property, etc. Adversely affect. Further, if the white pigment is less than 15 parts by weight, sufficient concealability cannot be obtained. Further, as a device for classifying the toner produced by the kneading-pulverization method, the degree of circularity and the like can be controlled by using toner particles such as a Tea Brex classifier (manufactured by Hosokawa Micron).
In addition, as a surface modification apparatus, apparatuses, such as hybridization made by Nippon Pneumatic Co., Ltd. described in Patent Document 1, can be used.

  Also, wet granulation methods include suspension polymerization method, emulsion polymerization method, emulsion polymerization association method, soap-free emulsion polymerization method, non-aqueous dispersion polymerization method, in-situ polymerization method, interfacial polymerization method, emulsion dispersion granulation method Etc. can be used.

Next, the configuration of an example of an image apparatus that forms an image using the white toner of this embodiment is shown in the schematic diagram of FIG.
In the image forming apparatus 20 of FIG. 1, the recording medium 25 wound around the supply roll 21 is conveyed by each feed roller 22, and black toner is transferred from the upstream side to the downstream side in the conveyance direction of the recording medium 25. The first image forming unit 23Bk for supplying to the recording medium 25, the second image forming unit 23C for supplying cyan toner to the recording medium 25, the third image forming unit 23M for supplying magenta toner to the recording medium 25, yellow The fourth image forming unit 23Y for supplying the toner to the recording medium 25 and the fifth image forming unit 23S for supplying white toner to the recording medium 25 are provided in this order.

  Then, on each side of the recording medium 25 fed by the feed roller 2, each toner is supplied from the first to fifth image forming units to an appropriate position so that a full-color toner image is formed on one side of the recording medium 25. Form continuously.

  A recording medium 25 on which a full-color toner image is continuously formed on one side is guided to a flash fixing device 24 using a flash lamp such as a xenon lamp by a feed roller 22, and a full-color toner formed on one side of the recording medium 25. The image is irradiated with infrared rays to fix the toner image on the recording medium 25.

  Here, in the fixing unit 24, a xenon lamp 24b that emits light by a light amount control unit (not shown) is disposed at the focal point of a reflecting mirror 24a having a parabolic cross section. Thereby, the light irradiated by one light emission is uniform, and the toner that forms the image melts uniformly due to its thermal energy. The amount of reflected light is detected by an optical sensor (not shown), and the voltage applied to the xenon lamp is adjusted by the light amount control means.

When the flash fixing device is used, in order to sufficiently fix the full-color toner image on the recording medium 1 while reducing the power consumption, the light emission energy of the flash lamp is set within a range of 3.0 to 7.0 J / cm ² . It is preferable to do.
Although this image forming apparatus shows a mode of full color image formation, it can also be used to form a single color image using only each color toner.

The white toner according to the present embodiment can also be used when a mark fabric is used for the recording medium. 2 and 3 are schematic views showing an example of the structure of the mark fabric. FIG. 2 is a cross-sectional view, and FIG. 3 is a perspective view.
The mark fabric 1 includes a woven fabric in which the warp is a metal yarn 3 and the weft is a normal yarn 2, an adhesive layer 4 below the woven fabric, and a protective sheet 5 on the back surface. Further, perforations 6 for conveyance are provided at both edge portions of the mark fabric 1. It is also possible to use a woven fabric in which the weft yarn is a metal yarn and the warp yarn is a normal yarn, or a woven fabric in which both the warp yarn and the weft yarn are metal yarns.

  As the metal yarn, a metal foil such as gold, silver, copper, aluminum, or the like, or metal fibers can be used. Moreover, natural or synthetic fibers, such as cotton, hemp, and nylon, can be used for the ordinary yarn.

  The image forming apparatus shown in FIG. 3 can also be used when mark fabric is used as the recording medium. The mark fabric wound in a roll is conveyed to each image forming unit at an appropriate speed by perforation, and after a toner image is formed, it is sent to a flash fixing device to fix the toner image on the mark fabric.

  The following effects can be obtained by using a non-contact heat fixing device for the mark fabric. Since the mark fabric contains metal, the reflectivity of the fabric is high and the amount of energy taken away by the fabric is small. Further, since the diffuse reflection is performed, the entire surface can be irradiated uniformly. As a result, efficient and good fixing can be performed on the mark fabric. Further, since the fabric reflects light, the temperature rise is small, the adhesive layer is not excessively heated, and the protective sheet is not peeled off.

  As described above, the white toner according to the present embodiment includes the achromatizing agent having a complementary color relationship with the infrared absorber, so that the toner can be achromatic. Thereby, not only the image quality can be improved, but also the color reproducibility can be improved. Needless to say, the fixing property can be improved by the infrared absorber.

Example 1
<Preparation of white toner>
(Preparation of binder resin)
As the binder, a polyester resin obtained as described below was used.
Polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, and terephthalic acid These were mounted with a hygrometer, a stainless stir bar, a flow-down condenser, and a nitrogen inlet tube together with a polymerization initiator dibutyltin oxide so that the molar ratio was 3: 7: 9. Placed in a glass four-necked flask.
Next, this four-necked flask was set in a mantle heater, and while the nitrogen was introduced into the flask from the above-mentioned nitrogen introduction tube, the reaction was conducted by heating and stirring, and the reaction state was measured while measuring the acid value during the reaction. The reaction was terminated when a predetermined acid value was reached, and this was cooled to obtain a polyester resin.

  The physical properties of the polyester resin thus obtained are as follows: number average molecular weight (Mn) is 3300, weight average molecular weight (Mw) / number average molecular weight (Mn) is 4.2, and glass transition temperature (Tg) is 68.5. The softening point (Tm) was 110.3 ° C., the acid value was 3.3 KOH mg / g, and the hydroxyl value was 28.1 KOH mg / g.

  Here, the glass transition temperature (Tg) is 20 using a differential scanning calorimeter (Seiko Denshi Co., Ltd .: DSC-200), using alumina as a reference, and a 10 mg sample at a temperature rising rate of 10 ° C./min. It measured between -120 degreeC and made the shoulder value of the main endothermic peak into the glass transition point.

As for the softening point (Tm), a flow tester (manufactured by Shimadzu Corporation: CFT-500) was used, a die having a pore diameter of 1 mm and a length of 1 mm was used, the pressure was 20 kg / cm ² , and the temperature was raised. The temperature corresponding to 1/2 of the height from the outflow start point to the end point of the outflow when a 1 cm ² sample was melted out under the condition of a rate of 6 ° C./min was defined as the softening point.

  As for the acid value, a 10 mg sample was dissolved in 50 ml of toluene, and consumption of N / 10 potassium hydroxide / alcohol solution evaluated in advance using a mixed indicator of 0.1% promthymol blue and phenol red. Calculated from the amount. The hydroxy value was expressed in mg of potassium hydroxide required to treat a weighed sample with acetic anhydride, hydrolyze the resulting acetyl compound, and neutralize the free acetic acid.

(Toner granulation)
The synthesized polyester resin was coarsely pulverized so that the particle size was 1 mm or less. Next, the polyester resin and titanium dioxide were charged into a pressure kneader in a weight ratio of 7: 3, kneaded at 120 ° C. for 1 hour, cooled, and then roughly pulverized with a hammer mill. Thus, a pigment master batch in which the white colorant content was 30 wt% was obtained.

  Next, the polyester resin and the pigment master batch are placed in a Henschel mixer so that the titanium dioxide is in a ratio of 7 parts by weight with respect to 100 parts by weight of the polyester resin, and the peripheral speed is increased by a Henschel mixer. Thorough mixing was performed at 40 m / sec over 180 seconds.

Next, this mixture was melt-kneaded with a twin-screw extruder kneader (Ikekai Tekko Co., Ltd .: PCM-30), the kneaded material was rolled to a thickness of 2 mm with a press roller, cooled with a cooling belt, and then mixed with a feather mill. Was coarsely pulverized. After that, this was pulverized by a mechanical pulverizer (manufactured by Kawasaki Heavy Industries, Ltd .: KTM) and further pulverized by a jet pulverizer (manufactured by Nippon Pneumatic Industrial Co., Ltd .: IDS), and then a rotor type classifier (manufactured by Hosokawa Micron Co., Ltd .: Teaplex). using type classifier 100 ATP) was classified to obtain a white toner particles _{W 0.}

(Surface modification)
Next, with respect to 100 parts by weight of the white toner particles W ₀ , 0.25 parts by weight of an aminium compound and 0.25 parts by weight of a cyanine compound are used as an infrared absorber, and hydrophobic silica (manufactured by Wacker: H2000) is used. These were mixed at a rate of 0.5 parts by weight with a Henschel mixer at a peripheral speed of 40 m / sec for 60 seconds, and then treated with a hybridization system (Nara Machinery Co., Ltd .: NHS-0 type) at 16400 rpm for 3 minutes. An infrared absorbent was fixed on the surface of the toner particles.

(Addition of external additives)
Next, 0.2 parts by weight of hydrophobic silica (manufactured by Wacker Co., Ltd .: H2000) and titanium oxide (manufactured by Titanium Industry Co., Ltd .: STT30A) with respect to 100 parts by weight of toner particles W ₀ to which the infrared absorbent is fixed as described above. ) And 0.5 parts by weight of strontium titanate having an average particle size of 0.2 μm were added at a rate of 1.0 part by weight, and these were mixed with a Henschel mixer at a peripheral speed of 40 m / sec for 60 seconds. open sieve 90μm sieve to obtain a white toner _{W 1.}

  Next, a white toner was prepared in which the addition amount of the infrared absorber was changed. Specifically, when the infrared absorber is immobilized on the surface of the toner particles by the hybridization system, only the amount of the infrared absorber added to 100 parts by weight of the toner particles is changed and shown in Table 1 below. A white toner was prepared. In any of the white toners, a mixture of equal amounts of an aminium compound and a cyanine compound was used as an infrared absorber.

(Addition of neutralizing agent)
As shown in Table 1 to prepare a white toner W ₃₁ with the addition of the achromatic agent white toner W _3. Specifically, following the step of preparing the master batch, the polyester resin and the pigment master batch are placed in a Henschel mixer so that titanium dioxide is in a ratio of 7 parts by weight with respect to 100 parts by weight of the polyester resin. When these are sufficiently mixed by a Henschel mixer at a peripheral speed of 40 m / sec over 180 seconds, 0.2 parts by weight of Pigment Red 122 is added as a coloring agent together with 7 parts by weight of titanium dioxide, and white toner W ₃₁ is added. Prepared.
Also for the white toner W ₄ , a neutralizing agent was added by the same method to prepare white toners W ₄₁ and W ₄₂ having the addition amounts shown in Table 1.

<Fixability evaluation>
Using the image forming apparatus shown in FIG. 3, white toner is applied to CF paper (basis weight 80 g / m ² ) as standard paper for CF 900 so that the total adhesion amount is 15 g / m ^2. The white toner was fixed on the recording medium by irradiation with 6 J / cm ² of infrared rays. When fixing strength (image density after rubbing / image density before rubbing) was determined from the image density before rubbing the obtained image with sand eraser and the image density after rubbing, except for W ₂ and W ₅ The fixing strength was 90% or more, and there was no practical problem. Also, with regard to fogging, dot reproducibility, and fine line reproducibility, good results were obtained except for W ₂ and W ₅ .

<Evaluation of spectral reflection characteristics>
Spectral reflection characteristics of the white toner, the infrared absorber, and the achromatic agent were measured using a color difference meter CM2000 (manufactured by Minolta).
FIG. 4 shows reflection spectra of an aminium compound and cyanine compound as infrared absorbers, and Pigment Red 122 as an achromatizing agent.
The aminium compound and the cyanine compound have a reflection peak from 500 nm to 600 nm, whereas Pigment Red 122 has an absorption peak from 500 nm to 600 nm, and the aminium compound and the cyanine compound, It can be seen that the pigment red 122 has a complementary color relationship. In the figure, the infrared absorber is abbreviated as IR agent.

Next, the reflection spectrum of the white toner _{W 3} and _{W 31} in Fig. W ₃₁ had a lower reflectance in the range of 500 to 600 nm than W ₃ and was able to suppress coloring due to the infrared absorber.

(Evaluation of brightness and saturation)
The brightness (L ^* ) and saturation (c ^* ) of the image obtained on CF paper were measured using a color difference meter CM2000 (manufactured by Minolta). The results are shown in Table 4.

For W ₃ , by adding 0.2 part by weight of the achromatizing agent, the saturation is greatly improved from 8.77 to 5.31 while maintaining the lightness at 90 or more, and is achromatic. I was able to. On the other hand, in the case of W ₄ where the addition amount of the infrared absorbing agent is 0.8 part by weight, the saturation can be greatly improved by adding the achromatizing agent, but the decrease in lightness becomes gray. The achromatic color was insufficient. For comparison, shows the results of W ₅ does not contain an infrared absorber. W ₅ is not good fixability, but the brightness is high and achromatic.

Example 2
The white toner W ₆ was obtained in the same manner as in Example 1 except that a halogen lamp was used as the light source of the fixing device and 0.3 part by weight of diimonium compound (IRG-023 manufactured by Nippon Kayaku Co., Ltd.) was used as the infrared absorber. Prepared. Further, the white toner W ₆ cyan-colored colorant in the achromatic agent in Pigment Blue 15: 3 was prepared white toner W ₆₁ was added 0.2 part by weight. Table 5 shows the evaluation results of lightness and saturation.

本実施例においても、無彩色化剤を添加することにより、明度を９０以上に維持しながら、彩度を大幅に改善することができた。また、トナーの定着性、カブリ、ドット再現性、細線再現性についても良好な結果が得られた。

Also in this example, by adding the achromatizing agent, the saturation could be greatly improved while maintaining the lightness at 90 or more. In addition, good results were obtained with respect to toner fixability, fogging, dot reproducibility, and fine line reproducibility.

FIG. 3 is a schematic diagram illustrating an example of the configuration of an image forming apparatus that uses the white toner of the present invention. It is a schematic cross-sectional view showing an example of the configuration of a mark fabric using the white toner of the present invention. FIG. 3 is a schematic perspective view of the mark fabric of FIG. 2. It is an example of the reflection spectrum of the infrared absorber used for the white toner of this invention, and an achromatic agent. It is an example of the reflection spectrum of the white toner of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mark fabric 2 Normal thread 3 Metal thread 4 Adhesive layer 5 Protection sheet 6 Perforation 20 Image forming apparatus 21 Supply roll 22 Feed roller 23Bk 1st image forming unit 23C 2nd image forming unit 23M 3rd image forming unit 23Y 1st 4 image forming unit 23S 5th image forming unit 24 flash fixing device 24a reflecting mirror 24b lamp 25 recording medium

Claims (3)

A non-contact fixing white toner used in an image forming apparatus for fixing toner on a recording medium by a non-contact heating device,
The white toner includes at least a white colorant, a binder resin that holds the colorant, an infrared absorber that absorbs infrared rays from the non-contact heating device, and a non-complementary color relationship with the infrared absorber. For non-contact fixing, which includes a colorant and has an L ^* value of 85 or more in the L ^* a ^* b ^* color system and a c ^* value defined by (a ² + b ² ) ^1/2 of 10 or less. White toner.   2. The non-contact fixing white toner according to claim 1, wherein the recording medium is a mark material. The non-contact fixing white toner according to claim 1, wherein the non-contact heating device is a flash fixing device.

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