JP2010079009A - Electrophotographic toner and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of manufacturing an electrophotographic toner, which excels in color developing property and also has a stable light resistance over a long period of time, and to provide an electrophotographic toner obtained by the method. <P>SOLUTION: The electrophotographic toner is obtained by kneading, pulverizing and classifying a mixture of a master batch, containing an organic UV absorbent with a binder resin and a colorant where the amount of the organic UV absorbent doped in the toner is 0.2 to 20 mass%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic toner and a manufacturing method thereof, and more particularly, to an electrophotographic toner excellent in light resistance and a manufacturing method thereof.

  The properties required for the pigment used in the electrophotographic toner are color development, transparency and light resistance. The color developability is caused by the chemical structure peculiar to the pigment, the transparency is largely caused by the pigment dispersion diameter, and the light resistance is caused by the particle diameter and the chemical structure. Among these, the light resistance is generally low because pigments are damaged by ultraviolet rays, and improvement thereof is desired. In particular, in recent diversification of output images of printers, there is an increasing demand for light resistance of toner for electrophotography.

As techniques for improving the light resistance of toner, there are those described in Patent Documents 1 to 4. In any of these techniques, an ultraviolet absorber is added to the toner in order to prevent damage to the pigment due to ultraviolet rays. However, it is difficult to obtain sufficient light resistance even with these ultraviolet absorbers, and since these ultraviolet absorbers have a large dispersed particle size in the toner, light scattering occurs, resulting in transparency and color development. There is a problem that is reduced.
JP-A-60-93453 JP-A-1-172773 JP-A-2-264264 JP-A-9-80797

  The present invention has been made under the circumstances as described above, and an object thereof is to provide an electrophotographic toner having excellent light resistance, color developability, and transparency, and a method for producing the same.

  In order to solve the above problems, a first aspect of the present invention is an electrophotographic toner obtained by kneading, pulverizing, and classifying a mixture of a masterbatch containing an organic ultraviolet absorber, a binder resin, and a colorant. In addition, an electrophotographic toner is provided in which the addition amount of the organic ultraviolet absorber in the toner is 0.2 to 20% by mass.

  The second aspect of the present invention is a step of kneading a mixture of a master batch containing an organic ultraviolet absorber, a binder resin, and a colorant with an open roll type kneader, and pulverizing and classifying the kneaded product. And a method for producing an electrophotographic toner, characterized in that the addition amount of the organic ultraviolet absorber in the toner is 0.2 to 20% by mass.

  According to the present invention, an electrophotographic toner having excellent light resistance, color developability, and transparency and a method for producing the same are provided.

  The best mode for carrying out the invention will be described below.

  An electrophotographic toner according to an embodiment of the present invention is obtained by kneading, pulverizing, and classifying a mixture of a masterbatch containing an organic ultraviolet absorber, a binder resin, and a colorant, and organic ultraviolet rays in the toner. The added amount of the absorbent is 0.2 to 20% by mass. In such an electrophotographic toner, since an organic ultraviolet absorber is blended in a master batch, it is highly dispersed in the toner and exhibits excellent color developability, transparency and light resistance.

  The organic ultraviolet absorber used in the electrophotographic toner according to an embodiment of the present invention is not particularly limited, and various conventionally known ones such as a benzotriazole ultraviolet absorber, a triazine ultraviolet absorber, and a benzophenone A UV absorber, a benzoate UV absorber, or the like can be used.

  Examples of the benzotriazole ultraviolet absorber include 2- (2H-benzotriazol-2-yl) -p-cresol and 2- (2H-benzotriazol-2-yl) -4-6-bis (1-methyl). -1-phenylethyl) phenol, 2- [5-chloro (2H) -benzotriazol-2-yl] -4-methyl-6- (tert-butyl) phenol, 2- (2H-benzotriazol-2-yl) ) -4,6-di-tert-benzylphenol, 2- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol, methyl-3- [3 -Condensate with t-butyl-5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate-polyethylene glycol (molecular weight about 300) 2- (2H-benzotriazol-2-yl) -6-dodecyl-4-methylphenol, 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole, 2-ethylhexyl-3- [3 -Tert-butyl-4-hydroxy-5- (5-chloro-2H-benzotriazol-2-yl) phenyl] propionate, 2- (2H-benzotriazol-2-yl) -4,6-bis (1- Methyl-1-phenylethyl) phenol, 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) Examples include phenol.

  Examples of the triazine ultraviolet absorber include 2- (4,6-bis (2,4-dimethylphenyl) -1,3,5-triazin-2-yl) -5-hydroxyphenyl, 2- (4,6- Diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] phenol, 2- [4-[(2-hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy-3- (2'-ethyl) hexyl) oxy] -2-hydroxy Phenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2-hydroxy-4-butyloxyphenyl) -6- (2,4-bis- Butyloxyphenyl)- , 3,5-triazine, 2- (2hydroxy-4- [1-octyloxycarbonyloxy] phenyl) -4,6-bis (4-phenylphenyl) -1,3,5-triazine, and the like. .

  Examples of benzophenone-based ultraviolet absorbers include octabenzone, 2,4-hydroxybenzophenone, 2-hydroxy-4-methoxy-benzophenone, 2-hydroxy-4-n-octyloxy-benzophenone, and the like.

  Examples of the benzoate UV absorber include 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate.

  These ultraviolet absorbers may be used alone or in combination of two or more.

  The organic ultraviolet absorbers listed above have been conventionally used in toners, but since the dispersed particle size in the toner is large and scattering is likely to occur, the transparency of the toner is impaired. In order to prevent this, in the present invention, a master batch obtained by kneading an ultraviolet absorber with a resin is used. By making only the ultraviolet absorber into a master batch, the dispersed particle size in the toner can be made as small as possible. As a result, the light resistance, transparency, and color developability of the toner can be improved.

  If an ultraviolet absorber in the form as it is without adding a masterbatch, a toner having excellent color development, transparency and light resistance cannot be obtained. The dispersion diameter of the ultraviolet absorber can be set to 200 nm or less in the toner particles by making a master batch. Moreover, as resin used for masterbatch formation, resin which is binder resin can be used.

The addition amount of the organic ultraviolet absorber in the toner is 0.2 to 20% by mass. That is, by making the ultraviolet absorber into a master batch, the amount of the ultraviolet absorber added can be increased to a maximum of 20% by mass. If it is less than 0.2% by mass, excellent color developability and transparency can be obtained, but light resistance is poor. If it exceeds 20% by mass, the color developability and transparency will be poor. A preferable range of the addition amount of the organic ultraviolet absorber is 0.5 to 5% by mass. Hereinafter, a method for producing an electrophotographic toner according to an embodiment of the present invention will be described more specifically.

  First, an organic ultraviolet absorber and a resin are kneaded to form an ultraviolet absorber master batch. As the kneader, it is desirable to use an open roll type kneader such as a continuous two-roll mill, a continuous three-roll mill, and a batch-type roll mill. The blending ratio of the organic ultraviolet absorber and the resin is not particularly limited, but it is desirable that the proportion is approximately equal.

  Next, the toner raw material containing the master batch, the binder resin, and the colorant thus obtained is mixed by a mixer. As a mixing machine, arbitrary things, such as a Henschel mixer, a super mixer, a V-type blender, and a Nauta mixer, can be used.

  The raw material mixture is then fed to a kneader where it is melt kneaded. As the kneader, it is necessary to use an open roll type kneader such as a continuous two-roll mill, a continuous three-roll mill, and a batch-type roll mill. By kneading using an open roll type kneader and using an organic UV absorber that has been made into a masterbatch, an organic UV absorber that is usually difficult to disperse in the binder resin is highly dispersed in the toner. It is possible to make it.

  On the other hand, when an extrusion kneader such as a twin screw extrusion kneader or a single screw extrusion kneader is used, an organic ultraviolet absorber that is difficult to disperse in the binder resin is high even in the form of a masterbatch. It becomes difficult to disperse, and the resulting toner results in poor color development and transparency.

  FIG. 1 is a front view showing an open type continuous two-roll mill. The open-type continuous two-roll mill includes two open-type rolls 12 and 13 arranged in parallel and a discharge unit 14 through which the kneaded material is discharged. Helical grooves for transporting the kneaded material are formed on the surfaces of the rolls 12 and 13.

  The raw material mixture supplied from the hopper 11 is supplied between the rolls 12 and 13 and is repeatedly compressed and kneaded by the rotation of the rolls 12 and 13 while being wound around the surfaces of the rolls 12 and 13. It moves to the discharge | emission part 14 side by the groove | channel on the surface, and a kneaded material is discharged | emitted there.

  FIG. 2 is a side view showing an example of a twin screw extrusion kneader. This twin-screw extrusion kneader includes a hopper 21 to which a raw material mixture is supplied, a cylinder 22 divided into a plurality of zones C1 to C8, and a die nozzle 23 from which a molten mixture is discharged. Each of the zones C1 to C8 of the cylinder 22 is heated to a predetermined temperature by a heater (not shown), and two cylinders are arranged in the cylinder 22 so that their axes are parallel or have a predetermined angle. A cylindrical screw (not shown) is arranged. The screw rotates in the same direction or in the opposite direction.

  The raw material mixture supplied from the hopper 21 is introduced into the cylinder 22 and is melted by the heat from the heated cylinder 22 in the gap between the screws, and is mixed by the compression force and shear force due to the rotation of the screw. Then, it moves to the die nozzle 23 side along the spiral blade of the screw and is discharged from the die nozzle 23.

  The melt-kneaded product from the kneader is usually cooled, pulverized, and classified to a predetermined particle size according to the method used for producing the toner to obtain an electrophotographic toner. The cooling means, the pulverizing means, and the classification means are not particularly limited, and those usually used for toner production can be employed. For example, a cooling means by rolling or blowing airflow can be used for cooling, an airflow pulverizer such as a collision plate pulverizer can be used for pulverization, and various airflow classifiers can be used for classification. it can.

  The binder resin usable in the electrophotographic toner according to the embodiment of the present invention described above 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.

  Examples of the colorant include the following.

  Examples of the color pigment for magenta include 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, 202, 206, 207, 209, 238, C.I. I. Pigment violet 19, C.I. I. Bat red 1, 2, 10, 13, 15, 23, 29, 35, etc. are mentioned.

  Examples of the color pigment for cyan include C.I. I. Pigment blue 2, 3, 15, 16, 17; I. Acid Blue 6; I. Acid Blue 45 or a copper phthalocyanine pigment having 1 to 5 phthalimidomethyl groups substituted on the phthalocyanine skeleton.

  Examples of the color pigment for yellow include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 16, 17, 23, 65, 73, 74, 83, 93, 97, 155, 180, C. I. Vat yellow 1, 3, 20 etc. are mentioned.

  The toner for electrophotography according to an embodiment of the present invention can contain a charge control agent and a release material in addition to a masterbatch containing a binder resin, a colorant, and an organic ultraviolet absorber. As the charge control agent and the release agent, any of those usually used for electrophotographic toners can be used.

  Examples of the present invention and comparative examples are shown below to describe the present invention more specifically.

Example 1
First, a UV absorber masterbatch is manufactured. The following binder resin 50.0% by mass and UV absorber 50.0% by mass were mixed in a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), and then a two-roll mill set at a roll surface temperature of 130 ° C. The mixture was kneaded for 45 minutes to obtain a UV absorber master batch.

Binder resin: Cross-linked polyester resin (softening point 141 ° C, glass transition point 62 ° C)
Ultraviolet absorber: 2- (2H-benzotriazol-2-yl) -p-cresol, 2- (2H-benzotriazol-2-yl) -4-6-bis (1 monomethyl-1-phenylethyl) phenol Next, the UV absorber master batch, the cross-linked polyester resin, the colorant, the release agent, and the charge control agent obtained as described above were mixed in a Henschel mixer (Mitsui Mining Co., Ltd.) with the following composition. ), And further melt-kneaded by an open roll type kneader (Needex: manufactured by Mitsui Mining Co., Ltd.).

Crosslinked polyester resin (softening point 141 ° C., glass transition point 62 ° C.) 92.8% by mass
Colorant (C.I Pigment Red 57: 1) 3% by mass
Release agent (Biscol 660P manufactured by Sanyo Chemical Co., Ltd.) 3% by mass
Charge control agent (E-84 manufactured by Orient Chemical Co.) 1% by mass
UV absorber 0.2% by mass
In addition, the compounding quantity of crosslinked polyester resin is the quantity containing the resin component of a ultraviolet absorber masterbatch, and the compounding quantity of a ultraviolet absorber is a substantial quantity contained in a masterbatch.

Table 1 below shows the kneading conditions by Kneedex.

  Thereafter, the melt-kneaded product is cooled, pulverized to a mass particle size of 8.8 μm with a collision plate pulverizer (“IDS-2” manufactured by Nippon Pneumatic Industry Co., Ltd.), and further classified by a classifier (Nippon Pneumatic Industry ( The resulting product was classified with “DSX-2” manufactured by Co., Ltd. to obtain 9.0 μm colored fine particles, and then 100 parts by mass of the colored fine particles and 1 part by mass of hydrophobic silica (“R972” manufactured by Nippon Aerosil Co., Ltd.) Mixing with a mixer gave a magenta toner.

Examples 2-6, Comparative Example 1
Six types of magenta toners were obtained in the same manner as in Example 1 except that the addition amount of the UV absorber was variously changed as shown in Table 3 below.

Comparative Examples 2 and 3
Two kinds of magenta toners were obtained in the same manner as in Example 1 except that the ultraviolet absorber was added in various amounts without adding a master batch.

Comparative Examples 4 and 5
A magenta toner was obtained in the same manner as in Example 1 except that the raw material mixture was kneaded by a biaxial extrusion kneader (PCM-43: manufactured by Ikegai Co., Ltd.).

Table 2 below shows the kneading conditions with PCM-43.

  The following characteristics were measured for the toner produced as described above.

1. Particle size measurement device: Multisizer II (manufactured by Coulter Co., Ltd.)
Sample: A small amount of sample, purified water, and a surfactant were placed in a beaker and dispersed with an ultrasonic cleaner.

  Measurement: The aperture was 100 μm, the count was 50,000, and the volume average particle size was obtained.

2. Evaluation of color development In a normal environment (25 ° C., 50% RH), toner is mounted on a non-magnetic one-component developing device “Casio Page Prest N-5” (manufactured by Casio Computer Co., Ltd .: 29 color printers per minute) The color developability of the solid print image was visually evaluated according to the following criteria.

(Evaluation criteria)
A: Color development is very good.

  ○: Color development is good.

  Δ: Slightly dull.

  X: It is dull.

3. Evaluation of OHP transmittance The toner was mounted on a non-magnetic one-component developing device “Casio Page Presto N-5” (Casio Computer Co., Ltd., color printer, 29 sheets per minute) in a normal environment (25 ° C., 50% RH). After printing a solid print image using OHP paper (dedicated OHP sheet N-OHPS), the obtained image was projected onto a screen with an overhead projector, and color development and transparency were evaluated according to the following criteria.

  A: Very transparent.

  ○: Good.

  Δ: Slightly cloudy.

  X: Dark.

4). Light fastness evaluation An image printed on plain paper “XEROX-L” with magenta toner mounted on “SPEEDIA N5300” (manufactured by Casio Computer Co., Ltd.) with the fixing oil supply device removed, made by Suga Test Instruments: Super A xenon weather meter SX-75 was used, the light source used was 7.5 kW xenon lamp / outer: # 275 / inner: quartz, and the accelerated light resistance test was conducted at a black panel temperature of 63 ° C. The difference in hue change (ΔE) was measured using “SPECTRODENSITOMETER 938” (manufactured by X-rite), and the degree of fading was evaluated according to the following criteria.

  (Double-circle): (DELTA) E is less than 2.0 and is especially favorable on actual use.

  A: ΔE is 2.0 or more and less than 5.0, which is good for practical use.

  (Triangle | delta): (DELTA) E is 5.0 or more and less than 10.0, and it can be actually used.

  X: ΔE is 10.0 or more and cannot be used.

The above measurement results are shown in Table 3 below.

  From Table 3 above, the following can be understood. The toners of Examples 1 to 6 obtained by kneading the raw material mixture containing 0.2 to 20% by mass of the UV absorber absorbed into a master batch with an open roll type kneading machine are color developing property, transparency, And excellent light resistance.

  On the other hand, the toner of Comparative Example 1 having an added amount of less than 0.2% by mass, even if it contains a masterbatch UV absorber, is inferior in light resistance. In addition, when an ultraviolet absorber that is not made into a masterbatch is used alone, the toner of Comparative Example 2 with a small addition amount is inferior in light resistance even in the range of 0.2 to 20% by mass. The toner of Comparative Example 3 having a large amount is inferior in color development and transparency.

  In addition, the toners of Comparative Examples 4 and 5 obtained by kneading with PCM-43, which is a biaxial extrusion kneader, also have poor color development and transparency.

It is a front view which shows an example of the open type continuous 2 roll mill used for one Embodiment of this invention. It is a front view which shows an example of the biaxial extrusion kneader used for the comparative example of this invention.

Explanation of symbols

  11, 21 ... Hopper, 12, 13 ... Roll, 14 ... Discharge part, 22 ... Cylinder, 23 ... Die nozzle.

Claims (2)

  An electrophotographic toner obtained by kneading, pulverizing, and classifying a mixture of a master batch containing an organic ultraviolet absorber, a binder resin, and a colorant, and the addition amount of the organic ultraviolet absorber in the toner is 0 2. An electrophotographic toner, wherein the toner content is 2 to 20% by mass. A step of kneading a mixture of a master batch containing an organic ultraviolet absorber, a binder resin, and a colorant with an open roll type kneader, and a step of pulverizing and classifying the kneaded product. A method for producing an electrophotographic toner, wherein the organic ultraviolet absorber is added in an amount of 0.2 to 20% by mass.

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