JPH07117771B2 - Magnetic color toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a toner for developing an electrostatic latent image or a magnetic latent image in electrophotography or electrostatic printing.
More specifically, the present invention relates to a magnetic color toner excellent in low-temperature fixability and offset resistance in a heat roller fixing method.

[Prior Art] Conventionally, as electrophotographic methods, many methods are known, such as US Pat. No. 2,297,691, Japanese Patent Publication No. 42-23910 and Japanese Patent Publication No. 43-24728. An electric latent image is formed on a photoconductor by various means using a conductive substance, and then an electrostatic latent image is developed by adhering toner onto the latent image. After the toner image is transferred onto the transfer material, it is fixed by heating, pressurizing, solvent vapor or the like to obtain an object.

In the developing system of the above process, in the method using the one-component magnetic toner, the toner is conveyed by a magnet roll to form a magnetic brush, and the magnetic brush is used as a photoconductor such as cadmium sulfide or an insulating electrostatic charge holder. Contact is made, the electric charge of the holding member and the induction static electricity or the triboelectricity static electricity held by the toner are attracted, and the toner adheres to the electrostatic charge holding member, so that development is performed. The developing method using the one-component magnetic toner does not require a device or the like for keeping the toner concentration in the developer constant as seen in the two-component developing method using carrier particles, and the developing device is simplified. Low cost or miniaturization is advantageous.

Various methods and devices have been developed as a method for fixing toner on paper or the like, but a method using heat is often used, and an oven fixing method is one example. However, in recent years, as the efficiency and energy saving of the copying work has been emphasized and the downsizing and speeding up of copying machines have been aimed at, the heat roller fixing method of pressure contact heating method, which is advantageous in terms of heat efficiency, has come to dominate. In such a method, the toner image on the paper is brought into direct pressure contact with the heat roller, which is extremely advantageous in terms of thermal efficiency, and is most suitable for speeding up from the viewpoint of the fixing property of the toner on the paper. However, it has a serious problem because of the method that takes such a way, that is, if the temperature of the heat roller is fixed to fix the toner, the toner adheres not only to the paper but also to the surface of the heat roller, and when the copying is repeated, the toner is not printed on the paper. Shows a so-called offset phenomenon that stains the non-image part of the.

Various measures have been sought for fixing devices and toners in order to solve or reduce such problems, but they have not been sufficiently solved.

As a fixing device, the surface of the heat roller is coated with a material such as Teflon or silicon, which has good mold release properties, and at the same time, a release oil such as silicone oil is applied to prevent fatigue of the roller surface. ing. However, the oil coating has problems such as complication of the fixing device due to the provision of the oil coating system in terms of cost and practically unfavorable.

As a toner, a method of adding waxes such as low molecular weight polyethylene and polypropylene to increase the releasability is also used. However, in order to sufficiently prevent offset, it is necessary to add a considerable amount, and as a result, adverse effects such as increase in toner cohesiveness, deterioration of durability due to deterioration of fluidity, destabilization of charging characteristics and the like are brought about. As another method, a method of improving the binder resin can be considered. For example, Japanese Patent Publication No. 51-2
Japanese Patent No. 3354 proposes a toner using a crosslinked polymer as a binder resin. According to this method, the offset resistance and the anti-sticking property are remarkably improved, but on the other hand, if the degree of crosslinking is increased, the fixing point rises. Further, a crosslinked polymer is difficult to disperse the pigment magnetic material, and is difficult to be compatible with other polymers, so that it is difficult to obtain good developing characteristics for a toner using a crosslinked polymer as a binder resin. There are drawbacks such as. Moreover, in order to measure high-speed fixing, it is necessary to lower the molecular weight of the resin and lower the softening point, which is contrary to the measure for improving the offset resistance. Further, this inevitably lowers the glass transition point of the resin, which causes an undesirable phenomenon that the toner is blocked during storage.

However, in conventional low-speed machines and medium-speed machines that do not require low-temperature fixing so much, process measures such as improvement of the fixing device as described above and improvement of toner, for example, crosslinking,
Due to measures such as the use of releasable additives, there was no problem at a practical level. However, basically, the above-mentioned dilemma has not been solved, and under the present circumstances, it is not possible to obtain a toner capable of fixing from an extremely low temperature and having a wide range of fixing temperature and having excellent offset resistance and blocking resistance.

By the way, recently, low molecular weight amorphous polyester resins and epoxy resins have been attracting attention as materials that match low temperature fixing. Among them, an attempt to use a polyester resin as a binder for a toner is known, for example, from Japanese Patent Publication No. Sho 12-12680.

According to these descriptions and the experiments conducted by the inventors, the fixing temperature is generally lower than that of other materials such as styrene-acrylic resin which has been widely used in the past, in the toner using the polyester resin as a binder. However, the offset resistance has not yet been improved.

The main idea up to now for preventing offset in a toner using a polyester resin as a main binder is to make a polymer skeleton non-linear by mixing a trivalent or more polyol and a polyacid as represented by JP-B-52-25420. It is intended to improve the offset property at the time of fixing and melting by imparting rubber elastic properties to the resin, and the inventors of the present invention also studied various examples of these, but certainly, the non-linearity of these is It is effective for improving the offset property, but this is also similar to the cross-linking in the styrene type, and if it is made non-linear until it has sufficient offset resistance, the fixing point rises and the low temperature of polyester resin The advantage of fixability is lost. Unlike the case of cross-linking styrene, when polyester is made non-linear or reticulated, the acid value and hydroxyl value of the resin obtained under the same reaction conditions greatly increase and the moisture resistance is increased. Cause sexual deterioration. Thus, considering various characteristics other than the offset resistance, there is a limit to the non-linearization of polyester.

Also disclosed in JP-A-56-116041 is the idea of mixing a polyvalent metal compound with a polyester resin and imparting a rubber elastic property to the resin by providing a cross-linking structure with a metal ion to improve the offset at the time of fixing and melting. Has been done. The inventors of the present invention also paid attention to this technique and investigated various metal compounds, but although it is confirmed that the effect of preventing offset on the heat roller is confirmed, most metal compounds do not contain a considerable amount. This is probably because the heat capacity of the toner is increased, but a defect that the fixing point is considerably raised appears.

As described above, the measures such as non-linearization of the polymer and metal crosslinking have a defect that the fixing point is increased, which basically does not match low temperature fixing. By introducing a soft segment into the polymer skeleton of various polyesters, the present inventors have developed a low temperature fixing dry toner for heat roller fixing which does not induce the above defects even when non-linearized or metal-crosslinked. Came to develop.

In particular, it has been found that the combination of the non-linearization and the metal cross-linking does not induce the adverse effect of the case where the non-linearization is carried out alone, and has a remarkable offset improving property. Therefore, it is an epoch-making thing that sufficient offset resistance can be guaranteed even if a very small amount or no oil is applied to the heat roller.

On the other hand, recently, there has been a wide variety of purposes of use, and there has been a demand for a multi-color copying machine that can obtain an image of a desired color as needed. The above-mentioned magnetic one-component developing method is suitable for small and inexpensive copying machines, but magnetic one-component toner has conventionally used magnetite or ferrite as the magnetic substance, and the color of these magnetic substances is black or black. Although it is dark brown, it is effective for obtaining a black toner, but it has been a major obstacle to obtaining a so-called color toner.

In order to conceal the color tone of the magnetic material, it is conceivable to reduce the amount of magnetic material in the toner, or to use a large magnetic material or to increase the amount of coloring pigment. When a large magnetic material is used, the dispersibility of the magnetic material is poor and the developability is poor. If the amount of the coloring pigment is increased too much, there is a problem that the developing property is lowered or the fixing property is lowered.

[Problems to be Solved by the Invention] The present invention has been made in view of the above points. That is, it is an object of the present invention to provide a color-rich magnetic color toner in which the color tone of a magnetic material is sufficiently hidden. A further object of the present invention is to provide a magnetic color toner having a good dispersibility of magnetic material.

A further object of the present invention is to provide a magnetic color toner that maintains stable chargeability over a wide temperature range and has excellent developing characteristics.

Its characteristic is that in a bis-based polyester based on etherified diphenols, when an aromatic acid as an acid component, especially terephthalic acid as a main component,
Even if it is made non-linear, there is little adverse effect on moisture resistance,
Further, by adding a small amount of an organometallic compound having a valence of 2 or more, the offset resistance can be improved very effectively, and the object of the present invention is to fix sufficiently at a lower temperature and save energy, which is particularly suitable for high-speed fixing. To provide a magnetic color toner.

A further object of the present invention is to provide a magnetic color toner having extremely good offset resistance and having a wide fixable temperature range from low temperature to high temperature.

A further object of the present invention is to provide a magnetic color toner having storage stability that does not cause blocking or aggregation even in a copying machine or in an atmosphere of relatively high temperature.

[Means and Actions for Solving Problems] The present invention relates to (A) (i) polyester having 10 to 25% by weight of 6 to 6 carbon atoms.
Succinic acid or its anhydride substituted with 18 alkyl groups, (ii) trivalent or higher polycarboxylic acids and / or trivalent or higher polyols, (iii) aromatics accounting for 50 mol% or more in all acid components Binder resin having a non-linear low melting point polyester having an acid value of 10 to 60, which is obtained by using a dicarboxylic acid-based compound and (iv) an etherified diphenol, (B) a divalent or higher valent organometallic compound, (C) ) A magnetic colorner obtained by heating and kneading a magnetic powder having a BET specific surface area of 0.3 to ⁵ m ² / g due to nitrogen adsorption, (D) phthalocyanine blue and (E) titanium white. For 100 parts by weight of resin
40 to 80 parts by weight of the magnetic powder, 5 parts of the phthalocyanine blue
˜15 parts by weight and 10 to 40 parts by weight of the titanium white are contained in the magnetic color toner.

The toner of the present invention is characterized in that the above problems are solved and that the dispersibility of the magnetic material is particularly good.

By introducing a specific alkyl-substituted succinic acid as a soft segment into the skeleton of polyester, it is possible to effectively prevent the increase of the fixing point due to non-linearity and metal crosslinking.

The reason for this is that the soft segment introduced into the polymer skeleton has the effect of loosening the reticulated skeleton and effectively lowers the anchoring point, further increasing the degree of freedom of the functional group to some extent according to the inference by the present inventors. It is considered that moisture resistance is improved by reducing COOH groups and OH groups. Moreover, since the C ₆ -C ₁₈ alkyl group as a soft segment is not incorporated in the main chain but is branched and introduced into the main chain, the toughness of the resin itself is not impaired.
In other words, when it is incorporated into the main chain, it becomes similar to linear polyester, and although the fixing point certainly lowers, the resin becomes brittle, and even when it is hot melt, the viscous property becomes stronger and the offset resistance also deteriorates. To be

As the soft segment component used in the polyester of the present invention, succinic acid having a C _{6 to} C ₁₈ alkyl substituent or an anhydride thereof is good, the fixing point is effectively lowered, and the moisture resistance improving effect is also remarkable. . Also, in polyester
It is necessary to contain 10 to 25% by weight, and more preferably 15 to 20% by weight. If it is less than 10% by weight, it becomes difficult to lower the fixing point effectively.
If it is more than 10% by weight, blocking tends to occur during storage.

Examples of the non-linear component include aromatic or other polycarboxylic acids having a valence of 3 or more, such as trimellitic acid, pyromellitic acid, cyclohexanetricarboxylic acids, 2,5,7-naphthalenetricarboxylic acid, 1,2, 4-naphthalene tricarboxylic acid, 1,2,4-butane tricarboxylic acid,
1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxylic propane, 1,3-dicarboxyl-2-methyl-2-methylenecarboxylic propane, tetra (methylenecarboxyl) methane, 1,2 , 7,8
-Octanetetracarboxylic acids and their anhydrides can be used. In addition, trivalent or higher polyol may be added,
For example, sorbitol, 1,2,3,6-hexanetetol, 1,4
-Sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4
-Mentatriol, glycerin, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol,
Trimethylolethane, trimethylolpropane, 1,3,
5-trihydroxymethylbenzene or the like can be used. As the polycarboxylic acids, these non-linear components are preferably contained in the polyester in an amount of 10 to 30% by weight, and the polyols are preferably contained in an amount of up to 5% by weight. If the polycarboxylic acid content is 30% by weight or more or the polyol content is 5% by weight or more, the moisture resistance is deteriorated. Offset property deteriorates.

Other than the above, as the main acid component of the polyester of the present invention, there are aromatic dicarboxylic acids or similar anhydrides, or other dicarboxylic acids, but in order to impart sufficient chargeability in electrophotographic characteristics, all acid components 50mol% in
The above must be aromatic dicarboxylic acids.
Aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, diphenyl-p, p'-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-2,6.
-Dicarboxylic acid, benzophenone-4,4'-dicarboxylic acid, 1,2-diphenoxyethane-p, p'-dicarboxylic acid and the like can be used, and terephthalic acid is particularly preferable. As other acids, maleic acid, fumaric acid, glutaric acid, cyclohexanecarboxylic acid, succinic acid, malonic acid, adipic acid and the like can be used.

Further, etherified diphenols are used as the diol component in the polyester of the present invention, and ethoxylated or propoxylated etherified diphenols are preferable.

The polyester used in the present invention has a glass transition temperature of 50.
It is preferable that the softening point is -80 ° C and the softening point is 60-130 ° C. When the glass transition temperature is less than 50 ° C or the softening point is less than 60 ° C, the obtained toner is likely to block during storage and become a practical defect. On the other hand, when the glass transition temperature exceeds 80 ° C. or the softening point is 130 ° C. or higher, an excessive amount of heat is required at the time of fixing, and the desired low temperature fixability is likely to be impaired.

Further, the polyester used in the present invention has an acid value of 10 to 60, preferably 20 to 50, but when the acid value is less than 10, the metal cross-linking is insufficient and there is a problem in offset resistance, and when it is 60 or more, the moisture resistance is Getting worse.

The polyvalent organometallic compound used in combination with the polyester is one that can react with the carboxyl group in the polyester, and examples thereof include salts of magnesium acetate, calcium acetate, basic aluminum acetate, calcium stearate, zinc stearate and the like; There are alkoxides such as aluminum isopropoxide, aluminum-n-butoxide and aluminum methoxide; chelate compounds such as aluminum acetylacetonate, nickel acetylacetonate and iron acetylacetonate; and various other metal complexes. Among them, the acetylacetone metal complex has a remarkable cross-linking reaction with the polyester used in the present invention, and the effect is great even in an extremely small amount.

In the present invention, the mixing ratio of the polyvalent organometallic compound to the polyester is preferably 0.2 to 4% by weight, and if it is less than 0.2%, there is a problem in offset resistance.

The magnetic powder used in the present invention is to contain a magnetic powder having a BET specific surface area by nitrogen adsorption of 0.3 to 5.0 m ² / g, preferably 0.5 to ⁴ m ² / g.

The magnetic color toner according to the present invention contains a binder resin, magnetic powder, phthalocyanine blue and titanium white as colorants, and a preferable composition ratio thereof is the binder resin 10
40 parts by weight to 80 parts by weight of magnetic powder, 5 to 15 parts by weight of phthalocyanine blue, and 10 to 40 parts by weight of titanium white.

When the composition ratio of the binder resin, magnetic powder, colorant, and titanium white in the magnetic color toner satisfies the above range, the color tone of the magnetic powder is sufficiently high as shown in the examples and the effects of the invention described later. It is possible to obtain a high-density toner image rich in colors in which the coloring effect of the colorant is sufficiently exerted.

The magnetic powder used in the present invention is BET by nitrogen adsorption.
There are powders of ferromagnetic elements having a specific surface area of 0.3 to 5 m ² / g and alloys and compounds containing them. For example, alloys and compounds of iron, cobalt, nickel, manganese, etc. such as magnetite, γ-hematite and ferrite. Other magnetic materials such as ferromagnetic alloys have been known in the past. Especially, magnetite is suitable for blue or green magnetic toner, and γ-hematite is suitable for yellow or red magnetic toner.

The specific surface area of the magnetic powder used in the present invention is shown above, the magnetic powder in the toner particles when the specific surface area of the magnetic powder is less than 0.3 m ² / g tends to be non-uniform, In addition, toner particles not containing a magnetic substance are also easily formed, and the image quality is deteriorated. On the other hand, when the specific surface area of the magnetic material exceeds 5 m ² / g, coloring due to the magnetic material becomes strong and coloring is less likely to occur, and the fixing temperature increases and the fixability decreases.

The magnetic material can be produced by any of a pulverization method, a method of growing particles during wet settling, a method of sintering a magnetic material, and a method of growing particles by a flux, but the particle size distribution of the magnetic material is narrow. The sintering method or the flux method is preferable because it is possible. Further, the magnetic material may be surface-treated if necessary.

The magnetic powder used in the present invention has a BET specific surface area of 0.3 to ⁵ m ² / g due to nitrogen adsorption. The volume-based cumulative 50% diameter is 1.0-6.5μ, the 25% diameter is 0.5-5.5μ,
It is desirable that the 75% diameter has a particle size distribution of 2.0 to 7.5μ. In this case, the particle size distribution of the magnetic powder is based on the value measured under appropriate conditions using a Coulter counter model TA-H type, 50 μ diameter aperture tube.

As a colorant used in the present invention, if necessary, an inorganic pigment, an organic dye or pigment can be optionally used, but a water-soluble dye is not preferable because it is weak against wetting even after image fixing, and a black color such as carbon black. The pigment and the like are not preferable in obtaining a color toner, but for the purpose of improving various characteristics, they can be used within a range that does not significantly deteriorate the characteristics of the toner of the present invention.

As the pigment used in the present invention, phthalocyanine blue is used for the purpose of obtaining a clear blue image.

The toner of the present invention may further be mixed with additives as required, and examples of such additives include metal-containing dyes, charge control agents such as nigrosine, polyvinylidene fluoride, polytetrafluoroethylene stearic acid. Lubricating agents such as zinc, or fixing aids such as low molecular weight polyethylene and polypropylene, fluidity imparting agents and anti-caking agents such as colloidal silica, and abrasives such as cerium oxide.

The magnetic color toner of the present invention comprises a binder resin, an organometallic compound having a valence of 2 or more, a magnetic powder having a specific BET specific surface area, phthalocyanine blue and titanium white, which are heated and kneaded as described in Examples below. Then, let it cool, crush, and
It can be produced by finely pulverizing with a Jetmill pulverizer or the like and classifying with a wind force classifier to adjust the particle size distribution.

Hereinafter, the present invention will be described in detail with reference to production examples and examples.

[Production Example 1] Production method of polyester resin A Polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane 1810 g and sorbitol 110 g were used as a thermometer, a stirrer, a glass introducing pipe and a flow-down type aggregator. Place in a 4-neck round bottom flask equipped with.

Nitrogen gas is flown in through the glass introduction tube to stir the polymer blend, and the reaction container is made to have an inert atmosphere. Then, heat to 50 ° C with continuous stirring, and add terephthalic acid.
Add 830 g, trimellitic acid 420 g, and 645 g of succinic acid having an alkyl substituent having 8 carbon atoms to the reaction vessel,
After the time reaction, the pressure was gradually reduced and the reaction was carried out at about 100 mHg, and the reaction was terminated when the softening point of the resin reached 100 ° C.

The obtained resin had a glass transition temperature of 65 ° C., an acid value of 30.0, a number average molecular weight of 6700, and a weight average molecular weight of 73,700.

[Production Example 2] Production method of polyester B In the same manner as in Production Example 1 except that sorbitol and trimellitic acid were not added, the reaction was terminated when the softening point of the resin reached 95 ° C. The obtained resin has a glass transition temperature of 58 ° C,
The acid value was 24.0, the number average molecular weight was 4,300, and the weight average molecular weight was 25,800.

[Production Example 3] Production Method of Polyester Resin C In Production Example 1, the succinic acid having an alkyl substituent having 8 carbon atoms was not added, and the same as above, but the acid value did not decrease even when the reaction time and the reaction temperature were variously changed. When the acid value reached 75, the reaction was terminated.

The obtained resin had a glass transition temperature of 85 ° C., a softening point of 142.5 ° C., a number average molecular weight of 8600 and a weight average molecular weight of 11,600.

[Production Example 4] Production Method of Polyester D The same procedure as in Production Example 1 was repeated except that the amount of succinic acid having an alkyl substituent having 8 carbon atoms was 1032 g and the amount of trimellitic acid was 210 g. When the reaction was completed. Obtained number average molecular weight 3800, weight average molecular weight 30,4
It was 00.

[Example 1] Polyester A 100 parts Magnetic powder (magnetite specific surface area 1.0 to 1.5 m ² / g 60 parts Phthalocyanine blue 10 parts Iron acetylacetonate 2 parts Polypropylene (molecular weight 10,000) 5 parts Titanium white (particle size 0.3 to 0.6 μ ) 20 parts The mixture of the above treatment is kneaded by heating on a hot roll at 150 ° C for 15 minutes, cooled and pulverized, further pulverized by a Jet mill pulverizer, and classified by an air classifier to obtain an average particle size of 10 to 15μ powder. Then, 0.5 part of colloidal silica was added to this to obtain a blue magnetic toner.When this magnetic color toner was imaged using a commercial copying machine (manufactured by NP-400RE Canon), it was very clear. A high-density blue image was obtained with a continuous copy of 50,000 sheets, and even after that, a high-density clear image was obtained, and the fixability and offset resistance were sufficient, and there was no change in color tone. There wasn't.

Example 2 A blue magnetic toner was obtained in the same manner as in Example 1, except that the iron acetylacetonate was changed to aluminum isopropoxide.

NP-400RE copier was used to remove the oil application device, and when the toner of Example 2 was used to continuously print 50,000 sheets, a clear image without fog was obtained to the end, and the fixability and offset resistance were also sufficient. It was something. Regarding the offset resistance, in particular, when the heat roller was observed at the end of the experiment, almost no toner fusion or the like was observed. Further, neither blocking nor agglomeration occurred during storage in the developing device hopper.

Comparative Example 1 A blue magnetic toner was obtained in the same manner as in Example 1 except that iron acetylacetonate was not added.

Comparative Example 2 A blue magnetic toner was obtained in the same manner as in Example 1 except that polyester B was used instead of polyester A.

Comparative Example 3 A blue magnetic toner was obtained in the same manner as in Example 1 except that polyester C was used instead of polyester A.

Comparative Example 4 A blue magnetic toner was obtained in the same manner as in Example 1 except that polyester D was used instead of polyester A.

[Comparative Example 5] The specific surface area in Example 1 is 1.0~1.5m ² / g, in the same manner to give a blue magnetic toner but using magnetic powder 7~9m ² / g instead of the magnetic powder, fraction When it was put out, only a slightly blackish blue image was obtained.

[Comparative Example 6] The specific surface area of Example 1 was 1.0 to 1.5 m ² / g, instead of the magnetic powder.
A blue magnetic toner was obtained in the same manner except that 0.15 to 0.2 m ² / g of magnetic powder was used, and when images were printed, only images with much fog were obtained. When continuous copying was performed, the image deteriorated after about 500 sheets.

The fixing properties and blocking properties of the toners of Examples 1 and 2 and Comparative Examples 1 to 6 were evaluated as follows.

To evaluate the fixability, the fixing unit of the NP-400RE copier was taken out, and the heat roller temperature was controlled at 100 ℃ to 250 ℃, and another fixing device capable of varying the linear velocity from 100 to 500 mm / sec was used.
The nip width was set to 8.5 mm, the surface of the heat roller was coated with Teflon, and the offset property and fixing point were evaluated without applying oil. The blocking property was evaluated by allowing 20 g of the toner to stand in a constant temperature bath at 50 ° C. for 24 hours, allowing it to cool at room temperature, and determining the degree of agglomeration.

Table 1 summarizes the above results.

The toners of Comparative Examples 1, 2, and 4 had good fixability, but the toner was fused to the heat roller, and an offset appeared in the image after 500 to 1000 sheets.

When the toner of Comparative Example 3 was left in a high temperature environment of 35 ° C. and 85% RH for 24 hours and then image formation was performed, the image density was low and image deletion occurred. In addition, when images were continuously printed on up to 99 sheets at a temperature of 5 ° C, the images were clear and good, but the fixability was insufficient and the images after 50 sheets were rubbed lightly by hand. The toner comes off the paper.

Comparative Example 7 A magnetic toner was obtained in the same manner except that the phthalocyanine blue used in Example 1 was omitted.

The color of the obtained magnetic toner was light gray.

Comparative Example 8 A blue magnetic toner was obtained in the same manner except that the titanium white used in Example 1 was omitted.

Image formation was performed in the same manner as in Example 1 using the obtained blue magnetic toner, and as a result, the blue color of the image was slightly blackish as compared with Example 1, and was not a clear blue color.

[Comparative Example 9] The average particle size was 0.2 in 10 l of 0.01 M zinc oxide aqueous solution kept at 25 ° C.
μ of γ-Fe ₂ O ₃ (50 g) was dispersed with stirring. Then, 10 l of 0.02 M sodium hydroxide aqueous solution kept at 25 ° C was added to 100 m.
After dripping at a rate of 1 / min and dripping completely, stirring was continued for 20 minutes, filtered, washed with water and dried to obtain a magnetic powder coated with zinc hydroxide. Then, it was left in air at 150 ° C. for 2 hours to obtain white magnetic powder coated with zinc oxide. The amount of the zinc oxide-treated magnetic powder obtained was 65 g.

CI Acid Blue 9 (60 g) was completely dissolved in water 1 at 25 ° C., and the above white magnetic powder (60 g) was dispersed with stirring with a stirrer. After that, 0.5 l of 0.1 M barium chloride aqueous solution kept at 25 ° C was added dropwise at a rate of 100 ml / min to completely add 1
The resulting lake was filtered, washed with water and dried in air at 40 ° C. to obtain a magnetic powder coated with a blue lake pigment. The amount of the magnetic powder double-coated with the obtained white pigment and blue pigment was 72 g.

Instead of 60 parts of magnetic powder, 20 parts of titanium white and 10 parts of phthalocyanine blue used in Example 1, 70 parts of magnetic powder doubly coated with the white pigment and blue lake pigment obtained above are used. A blue magnetic toner was obtained in the same manner as in Example 1 except for the above.

Using the obtained blue magnetic toner, an image was formed in the same manner as in Example 1. Initially, a clear and high-density blue image was obtained as in Example 1, but 50,000 consecutive sheets were obtained. After copying, the fluidity of the toner was lowered and fog was generated on the image, and a clear image could not be obtained.

[Advantages of the Invention] As described above, the magnetic color toner of the present invention uses the magnetic powder having a BET specific surface area of 0.3 to ⁵ m ² / g by nitrogen adsorption, so that the magnetic powder is uniformly dispersed in the toner particles. The deterioration of image quality and scumming are not likely to occur, and this property is maintained even in a low humidity environment.In addition, the coloring power of the magnetic material is weak, the coloring power of the magnetic powder is weak, and the color tone of the magnetic powder is sufficiently enhanced by titanium white. It can be used as a colorant for hiding, and can be used to form a particularly clear blue image. It becomes a toner that can obtain a very clear and high image density blue image in which the coloring effect of phthalocyanine blue is sufficiently exerted, and also binding Since the resin has an aromatic acid as a main component as the acid component of the bis type polyester based on etherified diphenols, it may adversely affect the moisture resistance even though it is non-linear. By adding a small amount and a small amount of an organometallic compound having a valence of 2 or more, the offset resistance is extremely good,
In addition, since a specific alkyl-substituted succinic acid is introduced as a soft segment in the polyester skeleton, the increase in the fixing point due to non-linearity and metal cross-linking is effectively prevented, sufficient fixing is achieved at low temperature, and energy saving is achieved. Is possible,
Suitable for high-speed fixing. Further, the toner of the present invention has a wide fixable temperature range from a low temperature to a high temperature, and does not cause blocking or agglomeration even in a copying machine or in a relatively high temperature atmosphere, and has excellent storage stability. Furthermore, the magnetic color toner of the present invention is obtained by heating and kneading a binder resin, a divalent or higher valent organometallic compound, a magnetic powder having a specific BET specific surface area, phthalocyanine blue and titanium white, Due to the action of titanium white contained in the magnetic color toner, the initial good fluidity of the toner does not easily deteriorate even after the endurance of a large number of sheets, and the kneaded product has a sufficient share. Since the content ratio of the magnetic powder is uniform, it is possible to obtain a clear image with a high image density and less fog even after the endurance of a large number of sheets.

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Claims (1)

[Claims] (1) 10 to 25% by weight in (A) (i) polyester
Succinic acid or an anhydride thereof substituted with an alkyl group having 6 to 18 carbon atoms, (ii) trivalent or higher polycarboxylic acids and / or trivalent or higher polyols, (iii) 5 in all acid components
Aromatic dicarboxylic acids accounting for 0 mol% or more and (i
v) Acid value 10 obtained using etherified diphenols
A binder resin having a non-linear low melting point polyester of 60 to 60, (B) a divalent or higher valent organometallic compound, (C) a magnetic powder having a BET specific surface area of 0.3 to ⁵ m ² / g due to nitrogen adsorption, (D) A magnetic colorner obtained by heating and kneading phthalocyanine blue and (E) titanium white, wherein the magnetic color toner is based on 100 parts by weight of a binder resin.
40 to 80 parts by weight of the magnetic powder, 5 parts of the phthalocyanine blue
-15 parts by weight and 10-40 parts by weight of the titanium white are contained in the magnetic color toner.