JPH03269543A - Image forming method - Google Patents

Abstract

PURPOSE:To form an image high in image density without inducing offset phe nomenon and paper winding trouble by using a polyester resin having viscoelasticity characteristics for a binder resin, and a polyester resinhaving proper compatibility with a magenta pigment made of 2, 9-dimethylquinacridne for a pigment processing resin. CONSTITUTION:The toner to be used is a color toner comprising the binder resin composed of a 10 - 40 wt.% tetrahydrofuran-insoluble fraction, and the processed pigment obtained by kneading a polyolefin wax, the magenta pigment made of the 2, 9-dimethylquinacridone and the polyester containing a<10wt.% tetrahydrofuran-insoluble fraction, thus permitting the binder resin not to be crushed by the pressure applied by the thin film forming member 4, and additives not to be buried by said pressure, and accordingly, a high-density image to be formed without inducing offset phenomenon and winding trouble.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image forming method applying electrophotography, electrostatic recording, electrostatic printing, etc. The present invention relates to a method of forming an image using a specific color toner by applying a two-component non-contact developing method using a thin layer forming member placed in pressure contact with each other.

[Conventional technology]

Color toners are usually comprised of pigments dispersed in a binder resin made of thermoplastic resin. but,
Pigments generally have a problem of poor dispersibility in binder resins.

However, various techniques listed below have been proposed to improve the dispersibility of pigments.

■ JP-A No. 62-280755 proposes a technique in which, instead of using the pigment as it is, a processed pigment obtained by kneading the pigment and resin is used and dispersed in a binder resin. . This publication particularly proposes using a polyester resin as the binder resin and using a polyester resin having a higher molecular weight than the polyester resin of the binder resin as the processed pigment resin.

■ In the specification of Japanese Patent Application No. 63-216311, a color is made of a binder resin having a weight average molecular weight of 100,000 or more and a processed pigment obtained by melt-kneading a pigment in a resin having a lower molecular weight than the binder resin. toner is suggested.

[Problem to be solved by the invention]

In the technique (2) above, when both the binder resin and the processed pigment resin are made of polyester resin, there is a possibility that the pigment can be well dispersed in the binder resin due to the compatibility between the two.

However, in the technique disclosed in JP-A No. 62-280755, polyolefin wax is contained in the binder resin in order to improve the fixing properties of the toner, and 8114 is a magenta pigment (hereinafter referred to as It has been found that the following problems occur when using quinacridone pigments (appropriately referred to as "quinacridone pigments").

In other words, quinacridone 11-1 has insufficient compatibility with the high molecular weight polyester resin used as the processed pigment resin, so it easily migrates into the low molecular weight polyester resin used as the binder resin, and therefore, it is difficult to mix with the pigment. Polyolefin wax, which has relatively good compatibility, is incorporated into the quinacridone pigment, and as a result, wax dispersion progresses, wax domains become smaller, and the amount of wax exposed on the surface of toner particles decreases, resulting in the offset phenomenon. A problem has arisen in that sufficient fixing properties are not exhibited due to the occurrence of .

Furthermore, it has been found that in the above-mentioned technique (2), the following problems occur when a polyolefin wax is contained in the binder resin in order to improve the fixing characteristics of the toner, and a quinacridone pigment is used as the pigment.

In other words, when a polyester resin with a low molecular weight is used as a processed pigment resin, the t-mime wax, which has good compatibility with the quinacridone pigment, is not incorporated into the quinacridone pigment, and the wax is insufficiently dispersed in the binder resin. In this case, the wax domain becomes excessively large, and the amount of wax exposed on the surface of the toner particles increases, resulting in an increase in the physical adhesion of the toner, resulting in a problem in which the image formation property is reduced and the image density is reduced.

This problem can be improved to some extent by adding and mixing inorganic fine particles such as hydrophobic silica fine particles from the outside of the toner particles. However, when an image is formed by a two-component non-contact developing method using a thin layer forming member placed in pressure contact with a developer transport carrier, toner particles are removed by the thin layer forming member when forming a thin layer. Because the pressure is considerably large, the improvement effect is likely to be lost due to inorganic fine particles being embedded in or detached from the toner particles, and therefore, when forming images multiple times, the physical The adhesion force increases, resulting in a significant decrease in image density.

In addition, when a binder resin with a molecular weight of 100,000 or more is subjected to pressure by a thin layer forming member in a two-component non-contact developing method using a thin layer forming member placed in pressure contact with a developer transport carrier, the strength against pressure is As a result, the inorganic fine particles that have been crushed or externally mixed into the toner particles are quickly buried, resulting in a problem in which the effect of the external additive is easily lost and the image density is lowered.

In this way, when a quinacridone pigment is used as a pigment, a polyester resin is used as a processed pigment resin, a polyester resin is used as a binder resin, and a polyolefin wax is used in combination, the quality of the polyolefin wax depends on the selected polyester resin. The fixing properties are not sufficiently exhibited, and on the contrary, the adverse effects of the tackiness of the polyolefin wax are increased, making it difficult to obtain a color toner suitable for the above-mentioned two-component non-contact development method.

An object of the present invention is to eliminate offset and wrapping phenomena when forming an image by applying a two-component non-contact developing method using a thin layer forming member placed in pressure contact with the surface of a developer transport carrier. It is an object of the present invention to provide an image forming method that can achieve good fixing in the image forming process and can also form an image with high image density even when the image is formed many times.

[Means to solve the problem]

In order to achieve the above object, the present inventor conducted extensive research and found that for the binder resin, a polyester resin having physical properties that are particularly resistant to pressure from the thin layer forming member was used, and for the processed pigment resin, a polyester resin with a physical property of 2.9 - By selecting a polyester resin that exhibits appropriate compatibility with the magenta pigment consisting of dimethylquinacridone, the polyolefin wax domain in the toner particles is within a suitable range, and as a result, both fixing characteristics and developability are fully satisfied. The present invention was completed by discovering this.

That is, in the present invention, when forming an image by applying a two-component non-contact developing method using a thin layer forming member placed in pressure contact with the surface of a developer transport carrier, as a toner constituting the developer, Tetrahydrofuran insoluble content is 10
A process obtained by kneading a polyolefin wax, a magenta pigment consisting of 2,9-dimethylquinacridone, and a polyester resin having a tetrahydrofuran insoluble content of less than 10% by weight in a binder resin consisting of a polyester resin having a content of ~40% by weight. A configuration using a color toner containing a pigment is adopted.

Further, the color toner is obtained by melt-kneading a binder resin, a polyolefin wax, a processed pigment, and other additives used as necessary, and in the kneaded product after the melt-kneading. It is preferable that the average value of the domain volume of the polyolefin wax is 5 to 20 μm 3 .

[Effect]

The polyester resin selected as the binder resin of the toner has a relatively high tetrahydrofuran insoluble content of 10 to 40% by weight, and therefore can impart appropriate viscoelastic properties to the toner, and is suitable for use when subjected to large pressure by the thin layer forming member. Also, the binder resin is not crushed and the external additives are not immediately buried.

In addition, the polyester resin selected as the processable P resin has a relatively small tetrahydrofuran insoluble content of less than 10% by weight, and has moderate compatibility with the magenta pigment consisting of 2,9-dimethylquinacridone. The magenta pigment has sufficient dispersibility and the domain of the polyolefin wax falls within a suitable range. As a result, when a two-component non-contact development method using a thin layer forming member is applied, there is no risk that the developability will be deteriorated due to physical adhesion caused by the polyolefin wax. Therefore, images with high image density can be stably formed many times without offset or wrapping phenomena.

In addition, in a color toner, the average domain volume of polyolefin wax in a kneaded product obtained by melt-kneading binder resin, polyolefin wax, processed pigment, and other additives used as necessary is 5. By having a thickness of ~20 μm3, the above-mentioned effect is reliably exhibited.

[Specific explanation of configuration]

Hereinafter, the configuration of the present invention will be specifically explained.

As the binder resin of the toner, a polyester resin having a tetrahydrofuran-insoluble content (THF-insoluble content) of 10 to 40% by weight is used.

By using a polyester resin having a THF-insoluble content within the above range as the binder resin of the toner, it is possible to impart appropriate viscoelastic properties to the toner. Therefore, even when a large pressure is applied by the thin layer forming member placed in pressure contact with the surface of the developer transport carrier, there is no risk that the toner will be crushed or external additives will be quickly buried in the toner, resulting in a good condition. Developability is exhibited. Furthermore, the toner's anti-offset properties and anti-wrapping properties are also improved.

Here, when the THF-insoluble content of the polyester resin used as the binder resin of the toner exceeds 40% by weight, the softening point increases and the fixing performance decreases, whereas when the THF-insoluble content is less than 10% by weight, the thin layer forming member In addition, the offset resistance and winding resistance are reduced.

The polyester resin used as a binder resin for toner is obtained by condensation polymerization of an alcohol component and an acid component, and in particular contains 40 to 60 mol% of etherified diphenols as the alcohol component, and contains etherified diphenols as the acid component. A polyester resin synthesized using a monomer containing 40 to 60 mol% of divalent or higher carboxylic acid and in which the proportion of the divalent carboxylic acid in the acid component is 70 to 95 mol% is preferred.

According to such a polyester resin, the domain of the polyolefin wax falls within a more suitable range, and excellent offset resistance and wrapping resistance are exhibited.

Examples of the etherified diphenols include polyoxyethylenated bisphenol A1, polyoxypropylenated bisphenol A, and the like.

Other alcohol components include ethylene glycol, diethylene glycol, triethylene glycol,
．． 2-propylene glycol, l.

3-propylene glycol, 1,4-butanediol,
Diols such as neopentyl glycol, 1.4-jf diol, polyquine propane (2,2)-2゜2-bis(4-hydroxyphenyl)propane, 1.4-bis<hydroxymethyl>cyclohexane, bisphenol A , hydrogenated bisphenol A, and the like.

Examples of divalent carboxylic acids include maleic acid, fumaric acid,
Mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sepatic acid, malonic acid, anhydrides or lower alkyl esters of these acids, riluic acid and other divalent organic acid monomers.

Examples of trivalent or higher carboxylic acids include 1, 2.4-benzenetricarboxylic acid, 1.3.5-benzenetricarboxylic acid, 1.2.4-cyclohexanetricarboxylic acid, 1
, 2.5-cyclohexanetricarboxylic acid, 2.5.7
-naphthalenetricarboxylic acid, 1.2.4-butanetricarboxylic acid, 1゜2.5-hexanetricarboxylic acid, l
, 3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra(methylenecarboxyne)methane, 1.2,7.8-octanetetracarboxylic acid, Empol trimer acid, anhydrides of these acids, Others can be mentioned.

As the processed pigment, a processed pigment obtained by kneading a magenta pigment made of 2,9-dimethylquinacridone and a polyester resin having a THF-insoluble content of less than 10% by weight is used.

The polyester resin used as the processed pigment resin is obtained by condensation polymerization of an alcohol component and an acid component, and has a THF-insoluble content of less than 10% by weight. Contains 60 mol% of divalent or higher carboxylic acid as an acid component.
A polyester resin synthesized using a monomer containing 60 mol % and in which the divalent carboxylic acid accounts for 70 to 95 mol % in the acid component is preferable. Specifically, the monomers used can be selected from among the monomers used in the synthesis of the polyester resin as the binder resin.

Since such a polyester resin has a THF-insoluble content of less than 10% by weight, its compatibility with the magenta pigment made of 2,9-dimethylquinacridone is moderate. Therefore, the domain of the polyolefin wax falls within a suitable range, and the fixing properties of the polyolefin wax are fully exhibited, and the development of tackiness due to the polyolefin wax is suppressed. As a result, when an image is formed by a two-component non-contact development method using a thin layer forming member, it is possible to form an image with high developability and high image density, and also to prevent offset and curling phenomena. Good fixing can be achieved without the need for

The blending ratio of the magenta pigment made of 2,9-dimethylquinacridone in the processed pigment is preferably 20 to 300 parts by weight per 100 parts by weight of the polyester resin as the processed pigment resin. Further, the proportion of the processed pigment in the entire color toner is preferably 2 to 50% by weight, and the proportion of the magenta pigment is preferably 1 to 20% by weight.

As a method for producing this processed pigment, for example, a granular or powdered polyester resin and a granular or powdered magenta pigment made of 2,9-dimethylquinacridone are mixed,
A method can be adopted in which the pigment is melt-kneaded, then cooled, and pulverized to obtain a granular or powdery processed pigment.

In the present invention, polyolefin wax is used as an essential component of the toner. As specific examples of polyolefin wax, polyethylene wax, polypropylene wax, etc. can be used. In order for polyolefin wax to fully exhibit its mold release effect, it must be thermally melted during fixing, and from this point of view, the softening point of polyolefin wax should be in the range of 100 to 160°C. preferable.

The blending ratio of polyolefin wax is 1 to 100 parts by weight of polyester resin as binder resin.
10 parts by weight is good.

In the above, the THF-insoluble content is measured as follows.

That is, the resin sample was finely ground, 5.00 g of sample powder that passed through a 40-mesh sieve was collected, and the sample was mixed with 5.00 g of the filter aid Radiolite (#700) in a volume of 1150 g.
m1' container, inject THFloog into this container, place it on a ball mill stand, and rotate it for 5 hours or more to fully dissolve the sample in THF.

On the other hand, place a filter paper (N (L2) with a diameter of 7 cm in the pressure filter, pre-coat 5.00 g of Radiolight evenly on it, and add a small amount of THF to tightly seal the filter paper to the filter. After that, pour the contents of the container into the filter.Furthermore, wash the container thoroughly with 100-THF and pour it into the filter so that no deposits remain on the wall of the container.Then, filter. Close the top lid of the vessel and filter.

Filtration is performed under a pressure of 4 kg/Cm' or less, and after the outflow of THF has stopped, THFloo- is newly added to wash the residue on the filter paper, and pressure filtration is performed again.

After the above operations are completed, the filter paper, the residue on it, and the radiolite are all placed on aluminum foil and placed in a vacuum dryer at a temperature of 80-100℃ and a pressure of 100m.
m) Dry for 10 hours under Ig conditions, measure the total weight 1a (g) of the dried product thus obtained, and calculate T by the following formula.
Determine the HF insoluble content X (% by weight).

X (wt%) Sampling weight (5,00 g) A method can be adopted in which the materials are premixed, then melt-kneaded, cooled, pulverized, and classified. Further, the toner may be further mixed with inorganic fine particles.

The average value of the domain volume of the polyolefin wax in the kneaded product obtained by melt-kneading the binder resin, polyolefin wax, processed pigment, and other additives used as necessary is 5 to 20 μm.
It is preferably in the range of 3. When the average value of the domain volume is within this range, the polyolefin wax can reliably exhibit excellent anti-offset properties and anti-wrapping properties, and can also provide an image with high image density.

In the present invention, the average value of the domain volume of polyolefin wax in a kneaded product is determined by forming the kneaded product into a plate shape, cutting 20 or more thin sections from this plate-shaped kneaded product, and calculating the average value of the domain volume of the polyolefin wax in the kneaded product. It refers to the average value when an enlarged photograph is taken using an optical microscope and the domain volume of wax is measured based on the obtained photograph.

The two-component developer used in the present invention is composed of a mixture of the above toner and a carrier. As such a carrier, for example, a coated carrier formed by coating the surface of magnetic particles such as ferrite with a resin can be preferably used.

In the present invention, an image is formed using the above two-component developer by applying a two-component non-contact developing method using a thin layer forming member placed in pressure contact with the surface of a developer transport carrier.

The developer transport carrier preferably includes a developing sleeve made of a rigid member and a magnet fixed inside the developing sleeve.

The thin layer forming member is preferably a rod-shaped member that is placed in pressure contact with the surface of the developing sleeve at a position facing a magnet fixed inside the developer transport carrier. The pressing portion of the thin layer forming member with respect to the developer transport carrier is made of a material having rigidity and magnetism, and the radius of curvature of the pressing portion is 0.
．． It is preferable that it is 5-15 mm. Here, "having rigidity" means that the rigidity is greater than or equal to IQ'kg/cm'.

The material for forming the surface of the developing sleeve can be selected from non-magnetic stainless steel, aluminum, hard resin, glass, ceramics, and the like.

In addition, as a constituent material of the thin layer forming member, 5US416
, magnetic stainless steel such as SO3430, iron alloy, hard resin containing magnetic powder, etc.

The pressing force of the thin layer forming member on the developing sleeve is 1 to 15 g.
f/mm is good. If this pressing force is too small, the ability to regulate the amount of developer decreases, making stable regulation difficult. On the other hand, when the pressing force is excessive, the load on the developer becomes large, which increases the adhesion of the developer to the thin layer forming member, making stable regulation difficult.

FIG. 1 shows an example of the configuration of a developing device suitable for carrying out a two-component non-contact developing method using a thin layer forming member placed in pressure contact with the surface of a developer transporting carrier.

The magnet body 2 constituting the developer transport carrier 1 is fixed inside the developer transport carrier 1, and N poles and S poles are alternately arranged on the outer periphery.

The developing sleeve 3 constituting the surface of the developer transport carrier 1 is
It is made of rigid non-magnetic stainless steel and rotates in the direction of the arrow.

The thin layer forming member 4 has a cylindrical bar shape with a radius of curvature of, for example, 3 mm in cross section, and is made of magnetic stainless steel (SO5416), which is a material having rigidity and magnetism.

The thin layer forming member 4 is located at a position facing the magnet body 2.
It is disposed in pressure contact with the developing sleeve 3, and regulates the amount of developer carried on the developing sleeve 3 supplied to the developing area 5.

This thin layer forming member 4 has been subjected to grinding processing to a surface roughness of 0.53, and is not provided with a surface coating. Note that a surface coating may be provided if necessary.

This thin layer forming member 4 is restricted from moving laterally by a holder 7 attached to the housing 6, and is pressed against the developing sleeve 3 with a pressing force of 1 to 15 gf/mm.

In FIG. 1, 8 is an image forming body, 9 is a first stirring member, 10 is a second stirring member, 11 is a supply roller, and 12
is a scraper, and 13 is a stirring partition plate.

In this developing device, the toner in the container is moved by a first stirring member 9 that rotates in the direction of the arrow and a second stirring member 10 that rotates in the opposite direction so as to overlap with each other.
After being sufficiently stirred and mixed with the carrier, it is conveyed to the surface of the developing sleeve 3 by the supply roller 11. That is, the first
The stirring member 9 and the second stirring member 10 are screw-shaped members with a left-handed spiral angle that rotate in opposite arrow directions, and are transported to the back side by the thrust of the second stirring member ■0. The mixed toner and carrier sequentially pass over the stirring partition plate 13 whose upper edge slopes low in the direction toward the back of FIG. 1, move toward the first stirring member 9, and are conveyed to the front side of FIG. The agitation and mixing action of the toner and carrier between them causes frictional electrification to form a spongy developer, and this spongy developer is transferred onto the circumferential surface of the developing sleeve 3 by the supply roller 11 rotating in the direction of the arrow. Adheres in layers.

The developer deposited on the developing sleeve 3 has a thickness of, for example, 100 to 450 μm when passing between it and the thin layer forming member 4.
A thin developer layer having a uniform thickness is formed, and this developer layer is supplied to the development area 5 and subjected to development.

The size of the minimum gap Dsd in the developing area 5 is larger than the thickness of the supplied developer layer, and an oscillating electric field is formed in the developing area 5.

〔Example〕

Examples of the present invention will be described below along with comparative examples, but the present invention is not limited to these embodiments. In addition,
In the following, "parts" represent "parts by weight."

<Example 1><Polyester resin A> Etherified diphenols 50 mol% terephthalic acid 30 mol% fumaric acid
12 mol% trimellitic acid
By condensing and polymerizing 8 mol% or more of the monomer, T
Polyester resin A having an HF insoluble content of 18% by weight was produced.

(Polyester resin B) Etherified diphenols 50 mol% terephthalic acid 25 mol% fumaric acid
20 mol% trimellitic acid
By condensing and polymerizing 5 mol% or more of monomers, T
Polyester resin B having an HF insoluble content of 8% by weight was produced.

(Processed pigment) Above polyester resin 8 60 parts 2.9-
Magenta pigment consisting of dimethylquinacridone
A processed pigment was prepared by melting and kneading 40 parts or more of the materials using a pressure kneader to form pellets.

(Color toner) Polyester resin A above 90 parts Polypropylene wax 3 parts Processed pigment A above
After premixing 10 parts or more of the materials using a Henschel mixer, they were melt-kneaded using an extruder, cooled, pulverized, and classified to obtain a powder with an average particle size of 13 μm. In addition, the average value of the domain volume of wax in the kneaded material after melt mixing is 10μ
It was m3.

Hydrophobic silica fine particles (Aerosil R-97
2, manufactured by Nippon Aerosil Co., Ltd.) was added and mixed in a proportion of 0.3% by weight to produce magenta color toner A.

(Two-component developer) The above color toner A and a carrier were mixed to produce a two-component developer having a toner concentration of 5% by weight.

The carrier used was a carrier in which a coating layer of styrene/methyl methacrylate copolymer resin was provided on the surface of ferrite particles.

(Image Formation) Using an image forming apparatus with a built-in developing device configured as shown in FIG. A live-action test was conducted to form the .

(Evaluation) The following items were evaluated. The results are shown in Table 1.

■ Wrap generation temperature and offset generation temperature In the above live-action test, a solid unfixed toner image with a width of 5 cm was formed only on the leading edge of the fixing paper, and then this unfixed toner image was fixed with a heat roller from the leading edge of the fixing paper. A test was conducted in which the fixing temperature was varied using a device, and the temperature at which curling occurred and the temperature at which offset occurred were measured. The heat roller fixing device used consists of an upper roller having a coating layer of PFA (tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer) and a lower roller having a coating layer of silicone rubber, and the load on the upper roller is as follows. 1
．． 5 kg/cm, and the linear velocity was set to 140 mm/s for the measurement of the winding generation temperature and 4 Qmm/s for the measurement of the offset generation temperature.

■Copy image density The relative density of the copy image was measured using a Sakura densitometer manufactured by Konica ■.

<Example 2> (Polyester resin C) Etherified diphenols 50 mol% Terephthalic acid 32.5 mol% n-
Dodecenyl succinic anhydride 5 mol % trimellitic acid 12.5 mol % or more of the monomers were polycondensed to produce polyester resin C having a THF-insoluble content of 32 wt %.

(Polyester resin D> Etherified diphenols 50 mol% Terephthalic acid 32.5 mol% n-
Dodecenyl succinic anhydride 5 mol % trimellitic acid 12.5 mol % or more monomers were condensed and polymerized to produce a polyester resin having a THF insoluble content of 5 wt %.

(Processing type f4) Above polyester resin D 70 parts 2.9
- magenta pigment consisting of dimethylquinacridone
Processed pigment B obtained by melting and kneading 30 parts or more of materials using a pressurized knee gun and pelletizing them.
was manufactured.

(Color Toner) Magenta color toner B was produced in the same manner as in Example 1 using 88 parts of the above polyester resin C, 3 parts of polyethylene wax, and 12 parts or more of the above processed pigment.

In addition, the average value of the domain volume of wax in the kneaded material after melt-kneading was 17 μm3.

(Two-component developer) A two-component developer was produced in the same manner as in Example 1, except that the above color toner B was used.

(Image Formation) A copy image was formed in the same manner as in Example 1 except that the above two-component developer was used.

<evaluation> The same items as in Example 1 were evaluated.

Comparative Example 1 (Polyester Resin E) Etherified diphenols 50 mol% Terephthalic acid 35 mol% Trimellitic acid 15 mol% or more of monomers were condensed to produce polyester resin E with a THF-insoluble content of 8% by weight. Manufactured.

<Processed pigment> Polyester resin D of Example 2 60 parts 29-
Magenta pigment consisting of dimethylquinacridone
A processed pigment C was prepared by melting and kneading 40 parts or more of the materials using a pressurized niegu to pelletize them.

(Color toner) The above polyester resin E 90 parts Polypropylene wax 2 parts The above processed pigment 0
Magenta color toner a was produced in the same manner as in Example 1 using 10 parts or more of the materials.

In addition, the average value of the domain volume of wax in the mixed wire material after melt-kneading was 30 μm'.

(Two-component developer) A two-component developer was produced in the same manner as in Example 1, except that the above color toner a was used.

(Image Formation) A copy image was formed in the same manner as in Example 1 except that the above two-component developer was used.

(evaluation) The same items as in Example 1 were evaluated.

Comparative Example 2 (Polyester Resin F) Etherified diphenols 50 mol% Terephthalic acid 30 mol% Fumaric acid 12 mol% Trimellitic acid 8 mol% or more of monomers were condensed and the THF-insoluble content was 24% by weight. polyester resin F
was manufactured.

(Processed pigment) 50 parts of the above polyester resin F2.
Maze pigment consisting of 9-dimethylquinacridone
A processed pigment was prepared by melting and kneading 50 parts or more of the materials using a pressurized knead and pelletizing them.

(Color toner) A magenta color toner b was produced in the same manner as in Example 1 using the following materials: 90 parts of polyester resin A of Example 1, 2.5 parts of polypropylene wax, and 10 parts or more of the above processed pigment D.

In addition, the average value of the domain volume of wax in the kneaded material after melt-kneading was 1 μm3.

(Two-component developer) A two-component developer was produced in the same manner as in Example 1, except that the above color toner b was used.

(Image Formation) A copy image was formed in the same manner as in Example 1 except that the above two-component developer was used.

(evaluation) The same items as in Example 1 were evaluated.

As is clear from the above embodiments, according to the present invention, when forming an image by applying a two-component non-contact developing method using a thin layer forming member placed in pressure contact with the surface of a developer transport carrier, , it is possible to achieve good fixing without causing offset phenomena and curling phenomena, and it is also possible to form images with high image density even when images are formed many times.

On the other hand, according to Comparative Example 1, the THF-insoluble content of the polyester resin E used as the binder resin was 8% by weight.
Because of this small size, the problem of reduced copy image density has occurred.

According to Comparative Example 2, since the THF-insoluble content of the polyester resin F used as the processed pigment resin was as large as 24%, both offset resistance and wrapping resistance were poor.

〔Effect of the invention〕

As explained in detail above, according to the present invention, THF of the polyester resin used as the binder resin of the toner
Because the insoluble content is relatively high at 10 to 40% by weight, the toner has moderate viscoelastic properties, and even when subjected to large pressure by the thin layer forming member, the toner particles are not crushed or externally added. There is no fear that the agent will be quickly buried in the toner particles, and therefore, a decrease in image density due to the physical adhesion of the polyolefin wax can be suppressed.

Moreover, since the THF-insoluble content of the polyester resin used as the processed pigment resin is relatively small at less than 10% by weight,
The compatibility with the magenta pigment consisting of 2.9-dimethylquinacridone is moderate, and therefore, the dispersibility of the magenta pigment in the toner is sufficient, and the domain of the polyolefin wax is in a suitable range, and as a result,
When applying a two-component non-contact development method using a thin layer forming member, there is no risk of deterioration in developability due to physical adhesion caused by polyolefin wax, and images with high image density can be produced without offset phenomenon or curling. It can be stably formed many times without any problems.

Moreover, if the average value of the domain volume of the polyolefin wax in the kneaded material after melt-kneading is in the range of 5 to 20 μm', the above effects are reliably exhibited.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a developing device that can be used to implement the present invention. l...Developer transport carrier 2...Magnet body 3...Developing sleeve 4...Thin layer forming member 5...Developing area 6...Housing 7...Holder
8... Image forming body 9... First stirring member 1
0... Second stirring member 11... Supply roller
12... Scraper 13... Stirring partition plate

Claims (2)

[Claims] (1) When forming an image by applying a two-component non-contact development method using a thin layer forming member placed under pressure on the surface of a developer transport carrier, tetrahydrofuran insoluble matter is used as the toner constituting the developer. It is obtained by kneading a polyolefin wax, a magenta pigment consisting of 2,9-dimethylquinacridone, and a polyester resin having a tetrahydrofuran insoluble content of less than 10% by weight in a binder resin consisting of a polyester resin having a content of 10 to 40% by weight. An image forming method characterized by using a color toner containing a processed pigment. (2) The color toner is obtained by melt-kneading a binder resin, polyolefin wax, processed pigment, and other additives used as necessary, and the kneaded product after the melt-kneading. The average value of the domain volume of polyolefin wax inside is 5 to 20 μm^3
The image forming method according to claim 1, characterized in that: