JPH03269542A - Image forming method - Google Patents

Abstract

PURPOSE:To form an image high in image density without inducing offset phenomenon and paper winding trouble by using a polyester resin having physical properties tough against strong pressure applied by a thin film forming member for a binder resin, and a polyerester resin having proper compatibility with a benzidine yellow type pigment for a pigment processing resin. CONSTITUTION:The toner to be used is a color toner comprising the binder resin composed of a 10-40wt.% tetrahydrofuran-insoluble fraction, and the processed pigment obtained by kneading a polyolefin wax, the benzidine yellow type pigment, 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 external 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.

Therefore, various techniques listed below have been proposed to improve the dispersibility of flil=l.

■ 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, with this technology, in order to improve the fixing characteristics of the toner, a polyolefin wax was included in the binder resin, and when a penzidine yellow pigment was used as the B material, the following problems were found. .

In other words, the penzidine yellow pigment 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, which makes it difficult to mix with the pigment. The polyolefin wax, which has relatively good compatibility, is incorporated into the Penzidine Yellow pigment, and as a result, the wax becomes more dispersed, the wax domain becomes smaller, and the amount of wax exposed on the surface of the toner particles is reduced. A problem arose in that an offset phenomenon occurred and sufficient fixing characteristics were not exhibited.

In addition, in the technique (2) above, in order to improve the fixing characteristics of the toner, polyolefin wax was contained in the binder resin, and it was found that the following problems occurred when a penzidine yellow pigment was used as the pigment. .

In other words, when a polyester resin with a low molecular weight is used as a processed pigment resin, the wax is not incorporated into the Penzidine Yellow pigment because it has good compatibility with the Penzidine Yellow pigment, and the wax is not dispersed in the binder resin. If the wax is insufficient, the wax domain becomes too large, and the amount of wax exposed on the surface of the toner particles increases, which increases the physical adhesion of the toner, resulting in a decrease in image formation and image density. arise.

This problem can be improved to some extent by adding and mixing inorganic fine particles such as hydrophobic phosphoric acid 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 10,000 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 are crushed or externally mixed into the toner particles are quickly buried, and the effect of the external additive is likely to be lost, resulting in a problem of lowering image density.

In this way, if a penzidine yellow 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 together, depending on the polyester resin selected, polyolefin wax may be used. The good fixing properties of the polyolefin wax 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 developing 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 intensive research and found that for the binder resin, a polyester resin that has physical properties that are particularly resistant to pressure from thin layer forming members was used, and for the processed pigment resin, Penzidine Yellow We have discovered that by selecting a polyester resin that exhibits appropriate compatibility with the pigment, the domain of the polyolefin wax in the toner particles can be set within a suitable range, and as a result, both fixing properties and developability can be fully satisfied. It is a completed invention.

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 processed pigment obtained by kneading a polyolefin wax, a penzidine yellow pigment, and a polyester resin having a tetrahydrofuran insoluble content of less than 10% by weight is contained in a binder resin consisting of a polyester resin having a content of ~40% by weight. Adopts a configuration that uses color toner.

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 processed pigment resin has a relatively small tetrahydrofuran-insoluble content of less than 10% by weight, and has moderate compatibility with the penzidine yellow pigment, so the dispersibility of the penzidine yellow pigment in the toner is improved. is sufficient and the domain of polyolefin wax is 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 CI 戊〕 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 also 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, polyquine propylenated bisphenol A, and the like.

Other alcohol components include ethylene glycol, diethylene glycol, triethylene glycol, l
, 2-propylene glycol, 1゜3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butanediol, polyoxypropane (
Examples include diols such as 2,2)-2°2-bis(4-hydroxyphenyl)furopane, 1,4-bis(hydroxymethyl)cyclohexane, bisphenol A, and hydrogenated hisphenol A.

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, 1
．． 3-dicarboxyl-2-methyl-2-methylenecarboxypropane, tetra(methylenecarboxyne)methane, 1,2,7.8-octanetetracarboxylic acid, embol trimer acid, anhydrides of these acids, etc. can be mentioned.

Processed pigments include Penzidine Yellow 1114 and T.
A processed pigment obtained by kneading with a polyester resin having an HF-insoluble content of less than 10% by weight is used.

Here, the penzidine yellow pigment refers to a yellow organic pigment of a 33'-dichlorobenzidine derivative. Specifically, C01, Pigment Yellow 12.13.14.15.17.55
．． 83 (C, 1, No, 21090.21100.21
095.21105) etc. can be cited as representative examples.

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.

According to such a polyester resin, since its THF-insoluble content is less than 10% by weight, the compatibility with the penzidine yellow pigment is moderate. Therefore, the domain of the polyolefin wax is in a suitable range, and the fixing properties of the polyolefin wax are fully exhibited.
The development of tackiness due to 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 penzidine yellow pigment in the processed pigment is preferably 20 to 300 parts by weight of the penzidine yellow pigment 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 penzidine yellow 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 penzidine yellow pigment are mixed, melt-kneaded, then cooled, and pulverized. It is possible to adopt a method of obtaining a processed pigment having a shape.

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.
Parts by weight of IO are preferred.

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 powder was collected with a volume of 150 g along with 5.00 g of the filter aid Radiolite (#700).
m1! THFloog was poured into the container, and the sample was placed on a ball mill stand and rotated for 5 hours or more to fully dissolve the sample in THF.

On the other hand, a filter paper with a diameter of 7 cm (of Nα2) was placed in a pressure filter, 5.00 g of Radiolite was evenly precoated on it, and a small amount of THF was added to make the filter paper adhere to the filter. Thereafter, the contents of the container are poured into a filter. Furthermore, the container is thoroughly washed with 10 (lae) of THF and poured into a filter to prevent any deposits from remaining on the wall of the container.Then, the top lid of the filter is closed and filtration is performed.The filtration is performed at 4 kg/cm. 'Performed under the following pressure, THF
After the outflow of the filter paper 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.
It was dried for 10 hours under conditions of mt 1 g, and the total weight 1a (g) of the dried product thus obtained was measured, and T
HFHF-insoluble charge amount%> is determined.

X (wt%) a (g) - Weight of filter paper (g) - Weight of Radiolite (
10,OOg) Heavy sampling! (5,00g) ×100 Toner manufacturing method involves premixing polyester resin as a binder resin, polyolefin wax, the above-mentioned processed pigment, and internal additives used as necessary, and then melting. A method of kneading, cooling, pulverizing, and classifying can be adopted. 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 it is possible to form an image with high image density.

In the present invention, the average value of the domain volume of polyolefin wax in a kneaded material is determined by forming the kneaded material into a plate shape, cutting 20 or more thin sections from this plate-shaped kneaded material, and enlarging these sections. It refers to the average value obtained when a 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 pressing portion has a radius of curvature of 0.
．． It is preferable that it is 5-15 mm. Here, "having rigidity" means that the rigidity is 10' kg/cm2 or more.

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/+y+m 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 type Fft 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 (SUS416), which is a material having rigidity and magnetism.

The thin-layer 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 1-158 f/mm.

In FIG. 1, 8 is an image forming body, 9 is a first stirring member, IO is a second stirring member, 11 is a supply roller, 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 rotating in the direction of the arrow and a second stirring member 10 rotating 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 helical rotation angle that rotate in opposite arrow directions, and are conveyed to the back side by the thrust of the second stirring member 10. The toner and carrier are transferred to the first stirring member 9 side by sequentially climbing over the stirring partition plate 13 whose upper edge is sloped low toward the back side in FIG. 1, and are conveyed to the front side in FIG. 1 by its thrust. 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 deposited in a layer on the circumferential surface of the developing sleeve 3 by the supply roller 11 rotating in the direction of the arrow. do.

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

The size of the minimum gap D□ 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 14% by weight was produced.

(Polyester resin B) Etherified diphenols 50 mol% Terephthalic acid 25 mol% Fumaric acid 20 mol% Trimellitic acid 5 mol% or more of monomers are condensed to form a polyester resin with a THF-insoluble content of 8% by weight. B was produced.

<Processed pigment> Polyester resin 8 60 parts Penzidine xo-based pigment (C, I, Pigment Yel
-1ow k17) A processed pigment A was produced by melting and kneading 40 parts or more of the material using a pressurized knee gun to form pellets.

<Color toner) Above polyester resin A 90 parts Polypropylene wax 3 parts Above processed R paddy Δ
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-kneading is 7 μm3
Met.

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 yellow color toner 8.

(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. We conducted a live-action test 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. is 1
．． 5 kg/cm, and the linear velocity was set to 140 mm/s in the measurement of the winding temperature and 4 Qmm/s in the measurement of the offset 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 35 wt %.

(Polyester resin D) Etherified diphenols 50 mol% terephthalic acid 32.5 mol% n-dodecenyl succinic anhydride 5 mol% trimellitic acid
A polyester resin having a THF-insoluble content of 5% by weight was produced by condensation polymerization of 12.5 mol % or more of the monomer.

<Processed pigment> The above polyester resin D 70 B penzidine yellow pigment (C, 1, Pigment Ye
tlovlN (L12) Processed pigment B was produced by melt-kneading 30 parts or more of the material using a pressurized knee gun and pelletizing it.

(Color Toner) Yellow 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 15 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 Penzidine yellow pigment (C, I, Pigment Ye
low No, 17)
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) A yellow color toner a was produced in the same manner as in Example 1 using 2 parts of the above polyester resin E 90 B polypropylene wax and 10 parts or more of the above processed pigment C.

The average domain volume of the wax after melt-kneading was 25 μm3.

<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
By condensing and polymerizing 8 mol% or more of monomers,
A polyester resin F having an F insoluble content of 18% by weight was produced.

(Processed pigment) Polyester resin F 50 parts Penzidine yellow pigment (C, 1, Pigment Yel
low No. 12) Processed product $4D was produced by melting and kneading 50 parts or more of the material using a pressurized knee gun and pelletizing it.

(Color toner) A yellow 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-mentioned processed pigment D.

In addition, the average value of the domain volume of wax in the kneaded material after melt W1 kneading was 3 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 wrapping 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 18%, 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
Since the insoluble content is relatively high at 10 to 40% by weight, the toner has appropriate 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 i11$4 resin is relatively small at less than 10% by weight, the compatibility with the penzidine yellow pigment is moderate, and therefore, the penzidine yellow pigment in the toner is In addition to sufficient dispersibility, the domain of the polyolefin wax is within a suitable range, and as a result, when a two-component non-contact development method using a thin layer forming member is applied, the physical adhesion force due to the polyolefin wax is reduced. There is no risk of deterioration in developability, and images with high image density can be stably formed many times without offset or wrapping phenomena.

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<3>, the above effects will be 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. A processed pigment obtained by kneading a polyolefin wax, a penzidine yellow pigment, and a polyester resin having a tetrahydrofuran insoluble content of less than 10% by weight is contained 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 color toner made of (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: