JP3503415B2 - Non-magnetic color toner - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-magnetic toner for developing an electrostatic latent image, and more particularly to a non-magnetic toner for developing an electrostatic latent image used in a full color image forming apparatus such as a full color electrostatic copying machine or a full color laser beam printer. Regarding toner.

[0002]

2. Description of the Related Art Conventionally, an electrostatic latent image formed on an electrostatic latent image carrier such as a photoconductor is developed with toner, and this toner image is transferred onto a recording member such as recording paper. Image forming methods for forming images are widely used in copiers, printers, facsimiles, etc., and in recent years, full-color image forming apparatuses that reproduce multicolor images by overlapping color toners of multiple colors have also been put into practical use. There is.

In such a full-color image forming apparatus, for example, an electrostatic latent image is formed in dot units on an organic photoconductor negatively charged by digital writing such as irradiation with a light beam, and the latent image is formed. Is subjected to reversal development using negatively charged magenta toner, cyan toner, yellow toner and, if necessary, black toner, and a toner image of each color is superposed to reproduce a multicolor image.

In recent years, miniaturization of a full-color image forming apparatus has been studied, but for that purpose, it is necessary to miniaturize the developing device. This is because the full-color image forming apparatus requires four developing devices containing cyan developer, yellow developer, magenta developer, and black developer, respectively. A non-magnetic one-component developing device, which does not require a stirring mechanism for toner and carrier, is advantageous for downsizing the developing device. However, in the case of a non-magnetic one-component developing device, a developer carrying member or a developer regulating member. However, there is a problem that toner adhesion tends to occur. This problem is particularly noticeable in full-color toners using a binder resin that requires translucency and exhibits sharp melting characteristics during fixing.

Further, conventionally, when a toner image carried on a transfer paper is fixed by a contact heat fixing method such as a heat roll fixing method or a belt fixing method, a member such as an upper fixing roller or a fixing belt comes into contact with the toner image. There is a problem that the melted toner is transferred, and the transferred toner re-attaches to the next transfer sheet to generate image noise (offset phenomenon).

As a technique for preventing the offset phenomenon, a technique of applying a releasing agent such as silicone oil to a fixing member which comes into contact with the toner, and a technique of containing a wax such as low molecular weight polypropylene in the toner are known. For full-color toners, a technique of applying a release agent to a fixing member is generally used. However, since this method requires a release agent coating mechanism and the like, a technique of incorporating wax into the toner has been studied from the viewpoint of downsizing of the full-color image forming apparatus. However, simply adding the wax cannot sufficiently improve the offset resistance, or the addition of the wax causes new problems such as filming on the photoreceptor.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a non-magnetic toner for forming a full-color image, which solves the above-mentioned problems.

That is, the present invention is excellent in offset resistance,
Another object of the present invention is to provide a non-magnetic color toner that solves the problem of filming on the photoconductor.

It is another object of the present invention to provide a non-magnetic color toner which solves the problem of toner sticking to the developer carrying member and the developer regulating member when used in the non-magnetic one-component developing system. .

[0010]

The present invention relates to a non-magnetic color toner containing at least a binder resin, a chromatic colorant and a wax, wherein the wax has an endothermic peak value in a calorimetric analysis of 130 to 138 ° C.
And the peak value in the weight molecular weight distribution is in the range of 7500 to 12000, and the endothermic peak value in the calorimetric analysis is 13
The melt blended wax with the oxidized polypropylene wax in the range of 8 to 150 ° C. is mixed with 100 weights of the binder resin.
It contains 0.5 to 5 parts by weight relative to the amount unit, melting Burendowa
And a non-magnetic color toner having an acid value of 0.5 to 20 KOHmg / g .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The non-magnetic color toner of the present invention is
A non-oxidizing polypropylene wax having an endothermic peak value in the calorimetric analysis in the range of 130 to 138 ° C., preferably 130 to 137 ° C. and a peak value in the weight molecular weight distribution in the range of 7500 to 12000, preferably 8000 to 11500. And an oxidized polypropylene wax having an endothermic peak value in the calorimetric analysis of 138 to 150 ° C, preferably 139 to 146 ° C. Here, the oxidized polypropylene wax represents a polypropylene wax modified with an acid monomer such as maleic acid, acrylic acid, methacrylic acid, and maleic anhydride, and the non-oxidized polypropylene wax is not modified in this way. Represents polypropylene wax.

When the endothermic peak value of the non-oxidized polypropylene wax is lower than 130 ° C. or when the endothermic peak value of the oxidized polypropylene wax is lower than 138 ° C., the offset resistance of the toner is deteriorated. On the other hand, if the endothermic peak value is too high, the dispersibility in the binder resin decreases and filming easily occurs. When the peak value in the weight-molecular weight distribution of the non-oxidized polypropylene wax is smaller than 7500, the toner adheres to the developer regulating member and the developer conveying member of the non-magnetic one-component developing device, and when it exceeds 12000, it is exposed. Filming to the body will occur.

In the present invention, the total content of the non-oxidizing polypropylene wax and the oxidizing polypropylene wax is 0.5 based on 100 parts by weight of the binder resin.
-5 parts by weight, preferably 0.5-4 parts by weight. If the total content of wax is less than 0.5 parts by weight, the effect of adding wax is insufficient, and if it exceeds 5 parts by weight, the translucency of the color toner deteriorates. The weight ratio of the non-oxidized polypropylene wax to the oxidized polypropylene wax (non-oxidized polypropylene / oxidized polypropylene) is 80/20 to 99.5 / 0.5, preferably 85.
/ 15 to 99/1.

Further, in the present invention, it is preferable to use a melt-blended wax obtained by melt-blending the above-mentioned non-oxidized polypropylene wax and oxidized polypropylene wax from the viewpoint of improving the dispersibility of the wax in the binder resin. . The acid value of the melt-blended wax is 0.5 to 20 KOHmg / g, preferably 1 to
10 KOHmg / g, more preferably 1-6 KOHmg
/ G. When the acid value is small, the effect of improving the dispersibility in the binder resin becomes small, and when the acid value is too large, the offset resistance is deteriorated.

As the binder resin used in the toner of the present invention, it is necessary to use a resin having a specific melting property in order to obtain excellent translucency and color reproducibility as a full-color toner in which the above-mentioned wax particles are dispersed. Yes, specifically, the melt viscosity at 100 ° C. is 5 × 10 ⁴ to 1 ×
10 ⁶ poise and melt viscosity V ₁ and 1 at 90 ° C.
00 ° C. in the melt viscosity V ₂ and the ratio V ₁ / V ₂ is 8 or more, preferably to use a V ₁ / V ₂ is 8 to 40. If the above V ₁ / V ₂ is smaller than 8, when the image having a low area ratio is reproduced, the surface smoothness of the dot image is impaired and diffuse reflection is likely to occur, resulting in insufficient translucency and color reproducibility. Become.

The type of resin is not limited as long as it is a binder resin having such melt viscosity characteristics, and for example, styrene-acrylic copolymer resin, polyester resin, epoxy resin and the like can be used. They can be used alone or as a mixture. Among these resins, polyester resin is particularly preferable.

The colorant used in the toner of the present invention includes:
Known dyes and pigments can be used and are not particularly limited. That is, the corresponding chromatic dyes and pigments may be used for the cyan, magenta, and yellow color toners, and carbon black is preferably used for the black toner.

It is preferable that the chromatic colorant used for the color toner has improved dispersibility of the colorant by a masterbatch process or a flushing process. The content of the colorant is 2 to 1 with respect to 100 parts by weight of the binder resin.
5 parts by weight is preferred.

Other than the above, desired additives such as a charge control agent may be added to the toner of the present invention.

As the charge control agent, known charge control agents can be used and are not particularly limited. Further, the charge control agent used for the color toner is the color tone of the color toner,
A colorless, white or pale color charge control agent that does not adversely affect the light transmittance can be used. For example, a salicylic acid metal complex such as a zinc complex of a salicylic acid derivative, a calixarene compound, an organic boron compound, and a fluorinated quaternary ammonium salt. It is preferable to use a charge control agent such as a compound. Examples of the salicylic acid metal complex include, for example, JP-A-53.
The compounds described in JP-A-127726 and JP-A-62-145255, the calixarene compounds described in, for example, JP-A-2-201378, and the organic boron compounds described in JP-A-2,2013, for example. -221
The compounds described in Japanese Patent No. 967, etc., and the fluorine-containing quaternary ammonium salt-based compound are, for example, JP-A-3-1162.
It is possible to use those described in Japanese Patent Publication No.

When such a charge control agent is added,
It is preferable to use 0.1 to 10 parts by weight, preferably 0.5 to 5.0 parts by weight, based on 100 parts by weight of the binder resin.

Further, in the present invention, it is preferable to add 0.2 to 3% by weight of inorganic fine particles to the toner particles. As such inorganic fine particles, silica, titania, alumina, strontium titanate, tin oxide, etc. surface-treated with a hydrophobizing agent can be used alone or in admixture of two or more. In addition to such an inorganic oxide, resin fine particles of 1 μm or less may be externally added.

The volume average particle diameter of the toner according to the present invention is preferably adjusted to 4 to 10 μm, preferably 5 to 9 μm from the viewpoint of high definition reproducibility of an image.

The toner of the present invention can be used as a toner for a two-component developer which is mixed with a carrier and as a toner for a one-component developer which does not use a carrier. In particular, from the viewpoint of downsizing of a full-color image forming apparatus, it has a configuration in which an elastic blade, which is a developer regulating member, is brought into pressure contact with a developing sleeve, which is a developer carrying member, and toner is passed when passing through a regulating portion. It is preferable to use in a non-magnetic one-component developing system for charging a.

When the toner of the present invention is used as a two-component developer, preferred carriers are, for example, resin-coated carriers obtained by coating magnetic particles of iron, magnetite, ferrite or the like with a resin, or fine magnetic powder. Is a binder-type carrier in which the above is dispersed in a binder resin. A resin-coated carrier using a silicone resin, a copolymer resin (graft resin) of an organopolysiloxane and a vinyl monomer or a polyester resin as a coating resin,
Alternatively, it is preferable to use a binder type carrier using a styrene-acrylic resin, a polyester resin or a mixture thereof as a binder resin from the viewpoint of toner spent and the like. The volume average particle size of the carrier is 2
It is preferable to use one having a thickness of 0 to 60 μm from the viewpoint of ensuring high image quality and preventing carrier adhesion.

[0026]

EXAMPLES The present invention will be specifically described below with reference to examples, but the invention is not limited thereto.

(Production Example of Non-oxidizing Polypropylene Wax N1) Polypropylene resin (melting point 165 ° C., molecular weight 1
(0,000) was cracked (pyrolysis) for 60 minutes through a tube heated to 400 ° C. by radiant heat of a burner from the outside. The endothermic peak value by DSC of the obtained non-oxidized polypropylene wax N1 was 134.6 ° C., and the peak value in the weight molecular weight distribution was 9650.

(Production Example of Non-Oxidized Polypropylene Wax N2) The endothermic peak value by DSC is 134.8 ° C. and the peak value in the weight molecular weight distribution is 11190 in the same manner as in the above production example of N1 except that the cracking time is 55 minutes. A non-oxidized polypropylene wax N2 was obtained.

(Production Example of Non-Oxidized Polypropylene Wax N3) The endothermic peak value by DSC is 134.2 ° C. and the peak value in the weight molecular weight distribution is 8240 in the same manner as in the production example of N1 except that the cracking time is 65 minutes. A non-oxidized polypropylene wax N3 was obtained.

(Production Example of Non-Oxidized Polypropylene Wax N4) In the same manner as in the production example of N1 above except that the cracking time was 70 minutes, the endothermic peak value by DSC was 133.1 ° C. and the peak value in the weight molecular weight distribution was 7040. Of non-oxidized polypropylene wax N4 was obtained.

(Production Example of Non-Oxidized Polypropylene Wax N5) The endothermic peak value by DSC is 137.5 ° C. and the peak value in the weight molecular weight distribution is 13500 in the same manner except that the cracking time is 50 minutes in the above production example of N1. A non-oxidized polypropylene wax N5 was obtained.

(Production Example of Non-Oxidized Polypropylene Wax N6) The endothermic peak value by DSC is 126.0 ° C. and the peak value in the weight molecular weight distribution is 6700 in the same manner as in the above production example of N1 except that the cracking time is 75 minutes. A non-oxidized polypropylene wax N6 was obtained.

(Production Example of Oxidized Polypropylene Wax S1) In the production example of N1 above, the cracking time is 4
450 parts by weight of the non-oxidized polypropylene wax and 50 parts by weight of maleic anhydride obtained in the same manner except that the time was set to 0 minutes were heated and dissolved in 500 parts by weight of xylene. 15 parts by weight of di-t-butyl peroxide was added to this solution, and the mixture was reacted at 180 ° C. for 5 hours while heating and stirring to obtain maleic anhydride-modified oxidized polypropylene wax S1. The endothermic peak value by DSC of the obtained oxidized polypropylene wax S1 was 143.2 ° C.

(Production Example of Oxidized Polypropylene Wax S2) In the production example of S1 above, the cracking time is 6
Oxidized polypropylene wax S2 having an endothermic peak value by DSC of 134.0 ° C. was obtained in the same manner except that it was set to 0 minute.

(Production Example of Melt-blended Wax B1) 450 parts by weight of non-oxidized polypropylene wax (N1) and 50 parts by weight of oxidized polypropylene wax (S1) are melt-blended to obtain a melt-blended wax B1 having an acid value of 4 KOHmg / g. Got

(Production Example of Melt Blend Wax B2) 475 parts by weight of non-oxidized polypropylene wax (N2) and 25 parts by weight of oxidized polypropylene wax (S1) are melt-blended to obtain a melt blended wax B2 having an acid value of 2 KOHmg / g. Got

(Production Example of Melt Blend Wax B3) 475 parts by weight of non-oxidized polypropylene wax (N3) and 25 parts by weight of oxidized polypropylene wax (S1) are melt-blended to obtain a melt blended wax B3 having an acid value of 2 KOHmg / g. Got

(Production Example of Melt Blend Wax B4) 475 parts by weight of non-oxidized polypropylene wax (N4) and 25 parts by weight of oxidized polypropylene wax (S1) are melt-blended to obtain a melt blended wax B4 having an acid value of 2 KOHmg / g. Got

(Production Example of Melt Blend Wax B5) 475 parts by weight of non-oxidized polypropylene wax (N5) and 25 parts by weight of oxidized polypropylene wax (S1) are melt-blended to obtain a melt blended wax B5 having an acid value of 2 KOHmg / g. Got

(Production Example of Melt-blended Wax B6) 400 parts by weight of non-oxidized polypropylene wax (N6) and 100 parts by weight of oxidized polypropylene wax (S2) are melt-blended to obtain a melt-blended wax B6 having an acid value of 8 KOHmg / g. Got

Example 1 Polyester resin (100 ° C.)
Melt viscosity at 1 × 10 ⁵ poise, melt viscosity at 90 ° C./melt viscosity at 100 ° C. = 9, softening point 98
C.) and cyan pigment (CI pigment blue 15:
3) and were mixed and kneaded in a pressure kneader so that the weight ratio of resin: pigment was 7: 3. The obtained kneaded product was cooled and then ground with a feather mill to obtain a pigment masterbatch.

93 parts by weight of the polyester resin, 10 parts by weight of the pigment master batch, 3 parts by weight of the melt blend wax (B1), and 3 parts by weight of a zinc salicylate complex (E-84; manufactured by Orient Chemical Industry Co., Ltd.) as a negative charge control agent. Was thoroughly mixed with a ball mill, and then the mixture was melt-kneaded with a twin-screw extrusion kneader (PCM-30; manufactured by Ikegai Tekko KK). The obtained kneaded product was cooled, coarsely pulverized with a feather mill, finely pulverized with a jet mill, and further finely classified to obtain colored particles having a volume average particle diameter of 8.0 μm. To 100 parts by weight of the colored particles, 0.5 part by weight of hydrophobic silica (Taranox 500; manufactured by Tarco) was mixed and added, and the colored particles were surface-treated with the hydrophobic silica to obtain a toner A.

Example 2 In Example 1, the melt blended wax (B1) was replaced with the melt blended wax (B2).
Toner B was obtained in the same manner except that the above was changed.

Example 3 In Example 1, the melt blended wax (B1) was replaced with the melt blended wax (B3).
Toner C was obtained in the same manner except that

(Comparative Example 1) In Example 1, the melt blended wax (B1) was replaced with the melt blended wax (B4).
Toner D was obtained in the same manner except that

(Comparative Example 2) In Example 1, the melt blended wax (B1) was replaced with the melt blended wax (B5).
Toner E was obtained in the same manner, except that

(Comparative Example 3) In Example 1, the melt blended wax (B1) was replaced with the melt blended wax (B6).
A toner F was obtained in the same manner except that the toner was changed to.

Comparative Example 4 Toner G was obtained in the same manner as in Example 1, except that the melt blended wax (B1) was changed to the non-acid value type polypropylene wax (N1).

Comparative Example 5 A toner H was obtained in the same manner as in Example 1 except that the melt blended wax (B1) was changed to the acid value type polypropylene wax (S2).

The above-mentioned molecular weight was determined by gel permeation chromatography (807-IT type; manufactured by JASCO Corporation) using tetrahydrofuran as a carrier solvent, and the molecular weight was calculated in terms of polystyrene.

The endothermic peak value of the wax was measured using a differential scanning calorimeter (DSC-200; manufactured by Seiko Denshi KK).

The acid value is represented by mg of potassium hydroxide required to dissolve a weighed sample in an appropriate solvent and neutralize an acidic group using an indicator such as phenolphthalein.

The melt viscosity and softening point of the resin were measured using a flow tester (CFT-500; manufactured by Shimadzu Corp.), and a 1.0 mm × 1.0 mm die was used for 1.0 g of the sample to raise the temperature. Speed 3.0 ° C / min, load 30k
The measurement was carried out under the condition of g, and the temperature when the sample flowed out by 1/2 was defined as the softening point.

The following evaluations were made on the above toners and the results are shown in Table 1.

(Offset resistance) An electrophotographic printer (SP-1000; manufactured by Minolta Co.) equipped with a non-magnetic one-component developing device was modified so that the set temperature of the fixing roller could be adjusted, and the set temperature of the fixing roller was changed. Images were printed and the temperature at which offset occurred was examined. Offset generation temperature of 180 ° C or higher is ⊚, 170 ° C or higher and lower than 180 ° C is ◯, 160 ° C or higher and lower than 170 ° C is Δ, 16
Those below 0 ° C were evaluated as x.

(Fixability) The above-mentioned SP-1000 photoconductor is removed, the above-mentioned toners are put into the developing device, and the developing sleeve is continuously rotated for 20 hours. Toner sticks to the developing sleeve and toner regulation blade, causing white streaks on the developing sleeve (a phenomenon in which a toner layer is not formed in streaks on the sleeve due to toner sticking to the regulating section), which causes noise on the image. If it appears x, white streaks are slightly generated but noise does not occur on the image and there is no problem in practical use △,
The case where no white streak was generated was evaluated as ◯.

(Filming) After printing 6000 sheets from SP-1000, the photoreceptor was visually evaluated and no filming was observed.
What was slightly observed but did not appear as noise on the image was evaluated as Δ, and what was observed as filming and also appeared as noise on the image was evaluated as x.

[0058]

[Table 1]

[0059]

According to the present invention, a non-magnetic toner for developing an electrostatic latent image used in a full-color image forming apparatus for reproducing a multicolor image by using magenta toner, cyan toner, yellow toner and black toner. It is possible to achieve both excellent offset resistance and filming property.
Further, according to the present invention, the problem of toner sticking to the developer carrying member and the developer regulating member can be solved even when used in the non-magnetic one-component developing system.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsunori Kurose 2-3-13 Azuchi-cho, Chuo-ku, Osaka, Osaka, Osaka International Building Minolta Co., Ltd. (56) Reference JP-A-8-240923 (JP, A) JP-A-8-234474 (JP, A) JP-A-8-166686 (JP, A) JP-A-8-106173 (JP, A) JP-A-8-82957 (JP, A) JP-A-6-208244 (JP, A) JP-A-4-358159 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 9/08

Claims (3)

(57) [Claims] 1. A non-magnetic color toner containing at least a binder resin, a chromatic colorant and a wax, wherein the wax has an endothermic peak value in the range of 130 to 138 ° C. in a calorimetric analysis and a weight molecular weight distribution. melt blending WAC of the non-oxidized polypropylene wax peak value is in the range of 7,500 to 12,000, an endothermic peak at calorimetry is the oxidized polypropylene wax in the range of one hundred and thirty-eight to one hundred fifty ° C. in
0.5 to 5 parts by weight per 100 parts by weight of binder resin
The acid value of the melt-blended wax is 0.5-2.
A non-magnetic color toner characterized by being 0 KOHmg / g . 2. The binder resin has a melt viscosity at 100 ° C. of 5 × 10 ⁴ to 1 × 10 ⁶ poise, and a ratio V ₁ / V of the melt viscosity V _{1 at} 90 ° C. and the melt viscosity V _{2 at} 100 ° C. nonmagnetic color toner according to claim 1 Symbol <br/> mounting ₂ is 8 or more. 3. The non-magnetic color toner according to claim 1, wherein the toner is a non-magnetic single-component toner.