JP5487904B2 - Decolorizing toner for electrophotography - Google Patents

Description

  The present invention relates to an electrophotographic decolorable toner, and more particularly to an electrophotographic decolorable toner capable of forming an image that is decolored by infrared irradiation.

  Conventionally, a decolorable toner using a near-infrared absorbing dye instead of a pigment is known. This decoloring toner shows a color close to blue under visible light. Further, a quaternary ammonium boron complex is added to the decoloring toner as a decoloring agent (see, for example, Patent Documents 1 and 2).

  When near-infrared rays are irradiated with a halogen lamp, laser, LED, or the like in a state where such a decolored toner printed matter is heated, the infrared absorbing dye in the toner is excited, and a quaternary ammonium boron as a decoloring agent. Reaction with the complex causes a decoloring reaction, and the toner on the printed matter is decolored. Due to such a phenomenon, the printing on the paper once printed is erased and can be used again.

  As described above, the decoloring toner promotes the decoloring reaction by irradiating near infrared rays while applying heat, but the power consumption required for the decoloring reaction is inevitably increased. However, if the power consumption is set low, the decoloring reaction is insufficient and a color residue occurs.

  Therefore, at present, there is a problem to be solved that it is difficult to cause a decoloring reaction sufficiently with low power consumption.

JP-A-5-119520 JP-A-5-278338

  The present invention has been made in view of the circumstances as described above, and provides a decoloring toner for electrophotography, a decoloring method, and a decoloring apparatus using the same, which exhibit a sufficiently excellent decoloring function even with low power consumption. For the purpose.

In order to solve the above problems, a first aspect of the present invention is a toner comprising at least a binder resin, a near-infrared absorbing dye, and a quaternary ammonium boron complex. providing electrophotographic decolorizable toner comprising a 15 mass% of Ca carbodiimide group-containing resin.

Here, the binder resin is a polyester resin, the upper hear carbodiimide group-containing resin functions as a modifier for a polyester resin in order to lower the acid value of the polyester resin.

  According to a second aspect of the present invention, the image is erased by irradiating a near-infrared ray onto a medium on which the image is formed by an electrophotographic process using the electrochromic toner. Provide erasing method.

  According to the present invention, a decoloring toner for electrophotography that exhibits a sufficiently excellent decoloring function even with low power consumption is provided. Further, it is possible to provide a method and apparatus capable of erasing a toner image with low power consumption.

Hereinafter, embodiments of the present invention will be described.
The decolorizing toner according to an embodiment of the present invention is a toner comprising at least a polyester resin as a binder resin, a near infrared absorbing dye, and a quaternary ammonium boron complex, and is 1 to 15 with respect to the total mass. It contains a polycarbodiimide resin by mass%.

  When a print or image is formed by an electrophotographic process using such a decoloring toner, the print or image appears to be a color close to blue under visible light, but when irradiated with near infrared rays in a heated state, the print or image is printed. The image disappears. This is based on the following phenomenon.

  That is, when near infrared rays are irradiated on a print or image at a temperature of, for example, 80 to 160 ° C., the near infrared ray absorbing dye in the toner is excited and reacts with the quaternary ammonium boron complex to cause a decoloring phenomenon. . As a result, the print or image is erased and the paper can be reused.

  The decolorization reaction occurs when the dye cation of the near infrared absorbing dye is bonded to the alkyl group of the quaternary ammonium boron anion.

  As the near-infrared absorbing dye contained in the decolorable toner according to this embodiment, conventionally known ones can be used. Examples of such near-infrared absorbing dyes include those described in the above-mentioned JP-A-5-119520. Specific examples of near-infrared absorbing dyes include IRT (trade name, manufactured by Showa Denko KK).

  A conventionally known quaternary ammonium boron complex can be used. An example of such a quaternary ammonium boron complex is described in JP-A-5-119520. A specific example of the quaternary ammonium boron complex is P3B (trade name, manufactured by Showa Denko KK).

  The binder resin can be selected from a wide range including known ones. Specific examples include styrene resins such as polystyrene, styrene-acrylic acid ester copolymers, styrene-methacrylic acid copolymers, and styrene-butadiene copolymers, saturated polyester resins, unsaturated polyester resins, and epoxy resins. Phenolic resin, coumarone resin, xylene resin, vinyl chloride resin, polyolefin resin and the like can be exemplified, and two or more of these resins may be used in combination. Of these resins, polyester resins are preferred.

  Polycarbodiimide resins include poly tert-butyl carbodiimide, polytetramethylxylylene carbodiimide, poly 2,4-toluylene carbodiimide, poly 2,6-toluylene carbodiimide, poly o-tolidine carbodiimide, poly 4,4'-diphenylmethane. Carbodiimide, poly 4,4'-dicyclohexylmethane carbodiimide, poly 4,4'-diphenyl ether carbodiimide, poly 3,3'-dimethoxy-4,4'-biphenyl carbodiimide, poly p-phenylene carbodiimide, polynaphthylene-1,5-carbodiimide , Poly m-xylylene carbodiimide, poly hydrogenated xylylene carbodiimide, polyhexamethylene carbodiimide, polytrimethylhexamethylene carbodiimide, polyisophorone carbodiimide Imide and the like.

  The decolorizing toner for electrophotography according to an embodiment of the present invention may contain a release agent and a charge control agent in addition to the binder resin, near infrared absorbing dye, quaternary ammonium boron complex, and polycarbodiimide resin. As the release agent and charge control agent, any of those usually used for electrophotographic toners can be used.

EXAMPLES Hereinafter, the Example and comparative example of this invention are shown and this invention is demonstrated more concretely.
-Toner creation-
Polyester resin CBC500 (softening point 113 ° C., glass transition point 60 ° C., manufactured by Kao Corp.) 90.25 parts by mass as a binder resin, and IRT (Showa Denko Co., Ltd.) 1.5 parts by mass as a near infrared absorbing dye , 3.75 parts by mass of P3B (manufactured by Showa Denko KK) as a color erasing agent, 2.5 parts by mass of Carnauba wax No. 1 powder (imported by Kato Yoko Co., Ltd.) as a release agent, polymer type charge control agent 2 parts by mass of FCA-2521-NS (manufactured by Fujikura Kasei Co., Ltd.) was weighed to a total of 100 parts by mass (10 kg), and mixed with a 20 L Henschel mixer at 2800 rpm for 3 minutes.

  Next, the mixture was supplied to a twin screw extruder (PCM-43: trade name, manufactured by Ikegai Co., Ltd.) and kneaded at 50 ° C. → 100 ° C. to obtain a kneaded product. The obtained kneaded product was cooled and pulverized with a coarse crusher, and then finely pulverized with an impact plate type pulverizer (IDS-2: trade name, manufactured by Nippon Pneumatic Co., Ltd.), and further an air classifier (CSX-2, The product was classified by a trade name, manufactured by Nippon Pneumatic Co., Ltd., and colored fine particles having an average particle size of about 9.0 μm were obtained.

  RY50 (trade name, manufactured by Nippon Aerosil Co., Ltd.) 2.0 parts by mass and RY200 (trade name, manufactured by Nippon Aerosil Co., Ltd.) 0.3 mass as hydrophobic silica with respect to 100 parts by weight of the obtained colored fine particles. Part, 0.5 parts by mass of alumina (AL45-2: trade name, manufactured by Showa Denko KK) is weighed to a total of 3 kg, introduced into a 20 L Henschel mixer, and 5 minutes at a peripheral speed of 40 m / sec. Then, the mixture was externally added and then sieved with a mesh having an opening of 100 μm to obtain a toner. This toner was designated as Comparative Example 1.

Comparative Examples 2-4, Examples 1-6
As shown in Table 1 below, the amount of addition of the polyester resin CBC500 was variously changed, and a comparative example was added except that 0.1 to 30% of polycarbodiimide LA-1 (trade name, manufactured by Nisshinbo Chemical Co., Ltd.) was added. In the same manner as in Example 1, a toner was obtained.

Comparative Examples 5-10, Examples 7-10
As shown in Table 1 below, the polyester resin was changed to CBC400, and the addition amount was variously changed, except that 0-30% of polycarbodiimide LA-1 (trade name, manufactured by Nisshinbo Chemical Co., Ltd.) was added. In the same manner as in Example 1, a toner was obtained.

Comparative Examples 11-14, Examples 11-16
As shown in Table 1 below, styrene-acrylic resin FSR-053 (trade name, manufactured by Fujikura Kasei Co., Ltd.) was used as the binder resin, and the amount of addition was varied, and polycarbodiimide LA-1 (product) No., manufactured by Nisshinbo Chemical Co., Ltd.) was added in the same manner as in Comparative Example 1 except that 0 to 30% was added.

Comparative Examples 15-17, Examples 17-22
As shown in Table 1 below, the addition amount of the polyester resin CBC500 was changed in various ways, and the polycarbodiimide was changed to SV-02 (trade name, manufactured by Nisshinbo Chemical Co., Ltd.) except that 0.1 to 30% was added. In the same manner as in Comparative Example 1, a toner was obtained.

Comparative Examples 18-20, Examples 23-28
As shown in Table 1 below, the addition amount of the polyester resin CBC500 was changed in various ways, and the polycarbodiimide was changed to N, N′-dicyclohexylcarbodiimide (manufactured by Wako Chemical) and added 0.1 to 30%. In the same manner as in Comparative Example 1, a toner was obtained.

  For the 48 types of toners according to Examples 1 to 28 and Comparative Examples 1 to 20 obtained as described above, the following characteristics were evaluated.

1. Decoloring reaction Toner was mounted on an N3500 printer (manufactured by Casio Computer Co., Ltd.) and printed on paper. In a state where the obtained printed matter was heated to about 70 ° C. on a heater rubber, 50 mW / cm ² of near infrared rays showing a peak of about 830 nm was irradiated from the LED for about 2 seconds, and the decoloring reaction was confirmed.

2. Measurement of density erasing rate Image density before irradiation of printed matter at this time was measured with X-rite in advance, image density after irradiation was measured with X-rite, and density reduction rate was calculated by the following formula .
Density erasing rate (%) = 100− (post-irradiation density / pre-irradiation density) × 100
The larger the value, the better the decoloring reaction.
The criteria for determining the decoloring reaction are shown below.
95% or more: ○
90% to 95%: △
89% or less: ×

3. Measurement of Acid Value The acid values of the toners obtained in Examples and Comparative Examples were measured using an automatic titrator COM-1600ST manufactured by Hiranuma Sangyo.

4). Measurement of softening point The softening points of the toners obtained in Examples and Comparative Examples were measured as T1 / 2 temperature (outflow start temperature) using a flow tester CFT-500D manufactured by Shimadzu Corporation.

5. Comprehensive evaluation The above decoloring reaction, acid value, and softening point were comprehensively evaluated.
The above evaluation results are shown in the evaluation result column of Table 1 above.

  The following can be seen from Table 1 above. That is, in Comparative Examples 1 and 2, the acid values were as high as 12 and 9, respectively. As a result of the decoloring test, the color was not completely erased, color residue was generated and the decoloring result was not good.

  On the other hand, in Examples 1-6, as a result of increasing the amount of carbodilite LA-1 from 0.5% to 20% and adding it, the acid value decreased as the addition amount increased, and the decoloring result was also good. This is presumably because carbodiimide is a condensing agent and thus reacts with the hydroxyl group of the polyester to cause a dehydration condensation reaction, resulting in a decrease in the acid value in the polyester.

  And when the acid value in the resin decreased, the tendency for the decoloring reaction to improve was observed because the near-infrared absorbing dye as the coloring material and the quaternary ammonium boron complex as the decoloring agent were in the near-infrared. It is considered that if the presence of a polar group such as a carboxyl group or a hydroxyl group in the resin is large during the decoloring reaction by absorbing a radical, the decoloring reaction is difficult to occur because the radical reaction is inhibited.

  On the other hand, it is presumed that a toner whose acid value has been lowered by adding carbodiimide as a condensing agent easily undergoes a decoloring reaction, and good results are obtained.

  In Comparative Examples 3 and 4, although the acid value was decreased by adding 25 or 30% of carbodilite LA-1, since the polymerization or crosslinking reaction of the polyester was promoted by the condensation reaction, the softening points were 127 and 128 degrees, respectively. High physical properties were shown. This is considered to be because when the softening point is increased, the viscosity is increased in the heating state during the decoloring reaction, so that the decoloring reaction is less likely to occur even when irradiated with near infrared rays.

  From this, it was found that by adding carbodilite LA-1, the acid value was lowered while the softening point was increased, so that a certain addition amount was effective for the decoloring reaction.

  Therefore, in Comparative Examples 5 to 7, 8 to 10, and Examples 7 to 10, the main resin is changed to the polyester resin CBC400 as described above, and toner is prepared and evaluated. As a result, similar effects were obtained when the amount of carbodilite LA-1 added was in the range of 1 to 15% specified in the present invention.

  On the other hand, in Comparative Examples 11 to 16 and Examples 11 to 16, a toner was prepared by changing the main resin to styrene / acrylic resin as described above, and the same evaluation was performed. As a result, it was found that the range of 1 to 15% specified in the present invention includes an effect on the decoloring reaction, and that the styrene / acrylic resin is also effective on the decoloring reaction.

  In Comparative Examples 15 to 17 and Examples 17 to 22, the carbodiimide type was changed from LA-1 to SV-02, and the toner was prepared by changing the addition amount, and the same evaluation was performed in this case. Results were obtained.

  Further, in Comparative Examples 18 to 20 and Examples 23 to 28, the carbodiimide was changed to N, N′-dicyclohexylcarbodiimide, and the toner was prepared and evaluated in the same manner, but the same evaluation results as in the above examples were confirmed. .

  From the above results, it has been found that the decoloring reaction is promoted by adding about 1% to 15% of a condensing agent having a carbodiimide group to the decolorable toner.

  The present invention can be used for a decolorable toner containing at least a near-infrared absorbing dye and a quaternary ammonium boron complex.

Claims (3)

A binder resin, and wherein the near infrared absorbing dye, a toner comprising at least a quaternary ammonium boron complex, and that relative to the total weight including 15 mass% of Ca carbodiimide group-containing resin Decolorizing toner for electrophotography. The binder resin is a polyester resin, an electrophotographic of claim 1, prior to hear carbodiimide group-containing resin which is characterized in that serve as modifiers for polyester resin to reduce the acid value of the polyester resin For decolorizing toner.   3. A color erasing method comprising: erasing the image by irradiating a medium on which an image is formed by an electrophotographic process using the color erasing toner for electrophotography according to claim 1 or 2 with near infrared rays. Method.