JPH10268571A - Yellow developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a yellow developer having excellent light-transmitting property and color reproducibility for an OHP and having excellent transfer property. SOLUTION: This developer is used for a full-color image forming method to reproduce a multicolored image. The developer contains negative charge nonmagnetic toner particles containing a binder resin having 1 to 30 KOHmg/g acid value, a compd. classified as a pigment yellow 180, and a compd. expressed by formula. In the formula, R1 , R2 are independently hydrogen atoms, 1 to 5C alkyl groups or -(CH2 )XCOOR5 groups (R5 is a hydrogen atom or lower alkyl group and X is an integer 1 to 3), R3 , R4 are hydrogen atoms, halogen atoms, or 1 to 12 C alkyl groups or aryl groups which may have branches, (l) is an integer 4 to 8, (m) is an integer 0 to 4, and (l+m) are 4 to 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a yellow developer for developing an electrostatic latent image, and more particularly to a yellow developer for developing an electrostatic latent image used in a full-color image forming apparatus such as a full-color electrostatic copying machine or a full-color laser beam printer. Agent.

[0002]

2. Description of the Related Art Conventionally, an electrostatic latent image formed on an electrostatic latent image carrier such as a photoreceptor is developed using toner, and this toner image is transferred onto a recording member such as recording paper. Image forming methods for forming images are widely used in copiers, printers, facsimiles, and the like. In recent years, full-color image forming apparatuses that reproduce a multicolor image by superimposing a plurality of color toners have been put to practical use. I have.

In such a full-color image forming apparatus, for example, an electrostatic latent image is formed for each dot on a negatively charged organic photosensitive member by digital writing such as irradiation of a light beam, and this latent image is formed. Is developed in reverse using magenta toner, cyan toner, yellow toner and black toner as required, and a multicolor image is reproduced by superimposing toner images of each color.

The above-described full-color image formation mainly includes a picture,
It is used to reproduce photographs, graphic images, and the like. As described above, a multicolor image is reproduced by superimposing a plurality of color toners. Such a multicolor image is widely used not only for forming an image on recording paper but also for an overhead projector sheet (OHP sheet). For this reason, the toner must have a spectral reflectance corresponding to a desired color, and have excellent translucency without hiding the color of the underlying toner during superposition. Is required. This requirement is particularly remarkable for a light yellow toner.

Conventionally known organic pigments and dyes have been known as colorants used in yellow toners, but each has various disadvantages. For example, since dyes generally exist in a state of being dissolved in a binder resin of a toner, they have excellent light transmittance and color saturation, but have a disadvantage that heat resistance and light resistance are low. I have. Since lightfastness is low and fading due to light occurs, there is a problem that even if an image having excellent chroma is obtained, it cannot be maintained for a long period of time. Further, when heat fixing is performed due to low heat resistance, the dye sublimates in the vicinity of the fixing portion, and there is also a problem that contamination in the apparatus easily occurs. In addition, there is also a problem in that some of them are dissolved in a release agent such as silicone oil applied to the fixing roller, and the image is stained. From such a viewpoint, it is preferable to use a pigment. However, since the pigment has a high cohesiveness and is difficult to be uniformly finely dispersed even in the toner, the hiding power of the toner is increased and the light transmittance is reduced. In addition, when the pigment particles are aggregated, the light scattering by the particles makes it impossible to obtain a spectral reflection characteristic for accurately reproducing the original, and the above-mentioned hiding power causes a sufficient transparency. When used for an OHP sheet, it has drawbacks such as a dark projected image and a low saturation when used for an OHP sheet because it cannot provide light properties. Further, some pigments have low heat resistance and are decomposed during the production of toner or heat fixing.

On the other hand, as described above, a full-color toner is required to have excellent transferability in order to reproduce a multicolor image by superposing toners of respective colors. If the charge amount of the toner is too high, the adhesion of the toner to the photoreceptor becomes strong, and the transferability decreases, and the transferability decreases even if the charge amount distribution of the toner is broad. For this reason, the full-color toner needs to have an appropriate charge amount and charge amount distribution.

In recent years, miniaturization of a full-color image forming apparatus has been studied. For this purpose, it is necessary to reduce the size of a developing device. This is because a full-color image forming apparatus requires four developing devices each containing a cyan developer, a yellow developer, a magenta developer, and a black developer. In order to reduce the size of the developing device, a non-magnetic 1 that does not require a stirring mechanism between the toner and the carrier
Although a component developing device is advantageous, in the case of a non-magnetic one-component developing device, the carrier is not used, so that the toner is charged by contact with a developer carrying member or a developer regulating member. A characteristic that quickly rises to a high charge amount is required.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a yellow developer for forming a full-color image which has solved the above-mentioned problems.

[0009] That is, an object of the present invention is to provide a yellow developer excellent in translucency and color reproducibility.

Another object of the present invention is to provide a yellow developer having excellent transferability even when forming a multicolor image.

Another object of the present invention is to provide a yellow developer which can be applied to a non-magnetic one-component developing system.

[0012]

According to the present invention, there is provided a yellow developer used for forming a full-color image for reproducing a multicolor image, wherein the yellow developer has at least an acid value of 1 to 1.
30 KOH mg / g binder resin, a compound classified as Pigment Yellow 180, and the following general formula (A):

[0013]

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(Wherein R ₁ and R ₂ are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or — (CH ₂ ) X C
An OOR ₅ group (R ₅ represents a hydrogen atom or a lower alkyl group, and X represents an integer of 1 to 3), and R ₃ and R ₄
Represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms and an aryl group which may have a branch. l represents an integer of 4 to 8, m represents an integer of 0 to 4,
+ M is 4 to 8. The present invention relates to a yellow developer containing negatively-charged non-magnetic toner particles containing the compound represented by the formula (1).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The full color yellow toner of the present invention contains C.I. I. Pigment Yellow 180. C.
I. Pigment Yellow 180 contains yellow toner, which is excellent in light transmission and color reproducibility. C.I. I. Pigment Yellow 180 is excellent in light resistance and heat resistance, so that it has excellent safety without decomposing to generate harmful substances even when heated during production or fixing of toner. . If the content is too small, sufficient saturation cannot be obtained, and if the content is too large, the influence on the charge of the toner becomes strong. I. Pigment Yellow 180 is preferably 2 to 15 parts by weight based on 100 parts by weight of the binder resin.

On the other hand, C.I. I. Pigment Yellow 180
In order to improve the dispersibility in the binder resin of
1.0 to 30.0 KOHmg /
g, preferably a resin having an acid value of 1.0 to 25.0 KOH mg / g, more preferably 2.0 to 20.0 KOH mg / g. This has an acid value of 1.0 KOHmg / g
If it is smaller, the effect of improving the dispersibility becomes small, and 30.0
This is because if the KOH is more than mg / g, the negative chargeability becomes stronger and the change in the charge amount due to environmental fluctuations becomes larger.

The type of the resin is not limited as long as it is a binder resin having such an acid value. For example, styrene-acrylic copolymer resin, polyester resin, epoxy resin and the like can be used. Or mixed and used. Among these resins, a polyester resin is particularly preferable.

In the present invention, a preferred polyester resin comprises a bisphenol A alkylene oxide adduct as an alcohol component as a main component, and a phthalic dicarboxylic acid or a phthalic dicarboxylic acid and an aliphatic dicarboxylic acid as an acid component. It is synthesized by a polycondensation reaction.

As the bisphenol A alkylene oxide adduct, bisphenol A propylene oxide adduct and bisphenol A ethylene oxide adduct are suitable, and it is preferable to use a mixture of these.

The following diols or polyhydric alcohols may be used as the alcohol component together with the bisphenol A alkylene oxide adduct. Examples of such alcohol components include ethylene glycol, diethylene glycol, triethylene glycol,
Diols such as propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, Pentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-
Examples include pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

Examples of the phthalic dicarboxylic acids include phthalic dicarboxylic acids such as terephthalic acid and isophthalic acid;
The acid anhydride or the lower alkyl ester thereof can be used.

The aliphatic dicarboxylic acids usable together with the phthalic dicarboxylic acids include aliphatic dicarboxylic acids such as fumaric acid, maleic acid, succinic acid, alkyl or alkenyl succinic acids having 4 to 18 carbon atoms, and acids thereof. Examples thereof include anhydrides and lower alkyl esters thereof.

In order to adjust the acid value of the resin, a small amount of a polycarboxylic acid such as trimellitic acid may be used as long as the light transmittance of the toner is not impaired. Examples of such a polyvalent carboxylic acid component include 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5-benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 2,4-naphthalene tricarboxylic acid, 1,
2,4-butanetricarboxylic acid, 1,2,5-hexanenetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid, tetra (methylenecarboxyl ) Methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, anhydrides thereof, lower alkyl esters and the like.

The binder resin used in the toner of the present invention has a glass transition point of 55 to 75 ° C., preferably 60 to 7 ° C.
0 ° C, softening point 95-120 ° C, preferably 100-1
At 18 ° C., the number average molecular weight is 2500 to 6000, preferably 3000 to 5500, and the weight average molecular weight / number average molecular weight is 2 to 8, preferably 3 to 7. When the glass transition point is low, the heat resistance of the toner is reduced, and when the glass transition point is high, the light transmittance and the color mixing are reduced. When the softening point is low, a high-temperature offset is likely to occur during fixing, and when the softening point is high, the fixing strength is reduced. When the number average molecular weight is small, the toner is easily peeled off when the image is bent, and when the number average molecular weight is large, the fixing strength is reduced. When the weight-average molecular weight / number-average molecular weight is small, high-temperature offset is likely to occur, and when it is large, the light transmittance is reduced.

The above-mentioned binder resin having a specific acid value, in particular, a polyester resin is C.I. I. Although the dispersibility of Pigment Yellow 180 is improved, the negative charge is very strong due to the acid value. Therefore, when used as a full-color toner, a problem arises in that transferability becomes insufficient. In addition, the charge rising characteristics are also insufficient, and fogging and the like are liable to occur, particularly when used as a non-magnetic one-component toner.

In order to solve these problems, the present invention provides the following general formula (A):

[0027]

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(Wherein R ₁ and R ₂ are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or — (CH ₂ ) X C
An OOR ₅ group (R ₅ represents a hydrogen atom or a lower alkyl group, and X represents an integer of 1 to 3), and R ₃ and R ₄
Represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms and an aryl group which may have a branch. l represents an integer of 4 to 8, m represents an integer of 0 to 4,
+ M is 4 to 8. Is contained in the toner. By containing this compound, the excessive negative charge of the toner having the above-mentioned acid value can be reduced to adjust the charge to an appropriate value, and the charge rising characteristics of the toner can be improved. In addition, the above compound has excellent heat resistance, does not decompose during the production of toner or fixing by heating, is a colorless substance, and has no adverse effect on translucency and color reproducibility even when used in a full-color toner. Also have.

In the above formula (A), preferred compounds are the following formula (B);

[0030]

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Wherein R ₁ and R ₂ have the same meanings as in formula (A), and n represents an integer of 1 to 7, or wherein R ₁ and R ₂ are those of formula (A) And n is 0
At least two different n's represented by
A mixture of more than one compound. Specific examples of the compound represented by formula (A) are shown below, but it should not be construed that the invention is limited thereto.

[0032]

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[0033]

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[0034]

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[0035]

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Such a compound is used as binder resin 10
0.1 to 10 parts by weight, preferably 0.1 to 10 parts by weight, based on 0 parts by weight.
It is preferable to contain 3 to 5.0 parts by weight. This is because if the content is too small, the effects described above, that is, the effect of lowering the charge amount of the toner to an appropriate range and the effect of improving the rise property of the toner charge cannot be sufficiently obtained, and the content is too large. In the case of two-component development, the above compounds tend to transfer to the carrier when printing is performed, and to the developer carrying member or developer regulating member when one-component development is used, so that the toner obtains an appropriate charge amount. Can not be.

Further, if necessary, waxes such as low-molecular-weight polypropylene wax, low-molecular-weight polyethylene wax, carnauba wax and sasol wax may be added to improve the offset resistance. Especially when the acid value is 0.5
Waxes of up to 30 KOH mg / g are preferred from the viewpoint of dispersibility in the binder resin having the above acid value.

In the present invention, the yellow toner can be produced by a known method, and is not particularly limited. can do. In addition, when adding the yellow pigment in the production process, it is preferable to use a master batch-treated or flushed yellow pigment from the viewpoint of improving the dispersibility.

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

In the present invention, it is preferable to externally add 0.2 to 3% by weight of inorganic fine particles to the yellow toner particles from the viewpoint of improving fluidity and the like. As such inorganic fine particles, silica, titania, alumina, strontium titanate, tin oxide and the like can be used alone or in combination of two or more. It is preferable to use inorganic fine particles that have been surface-treated with a hydrophobizing agent from the viewpoint of improving environmental stability. Further, other than such an inorganic oxide, resin fine particles of 1 μm or less may be externally added.

The yellow developer of the present invention can be used as a two-component developer used by mixing with a carrier or as a one-component developer not using a carrier. In particular, from the viewpoint of miniaturization of the full-color image forming apparatus, the image forming apparatus has a configuration in which a blade that is a developer regulating member is pressed against a developing sleeve that is a developer carrying member. It is preferable to use it for a non-magnetic one-component developing system for charging.

When the toner of the present invention is used as a two-component developer, a preferable carrier is, for example, a resin-coated carrier obtained by coating magnetic particles such as iron, magnetite, and ferrite with a resin, or a magnetic fine powder. Are dispersed in a binder resin. A resin-coated carrier using a silicone resin as a coating resin, a copolymer resin (graft resin) of an organopolysiloxane and a vinyl monomer or a polyester resin,
Alternatively, it is preferable to use a binder type carrier using a styrene-acrylic resin, a polyester resin or a mixture thereof as the binder resin from the viewpoint of toner spent.

A preferable two-component developing method is that a thin developer layer, specifically 0.7 to 10 m, is placed on a developer carrying member (developing sleeve) in which a magnet roller is fixedly arranged.
g / cm ^2, preferably carries a developer layer with a developer of 1~7.5mg / cm ^2, and supplied to the developing region, an oscillating electric field in the developing region, preferably superimposes a DC voltage and an AC voltage This is a development method in which development is performed under the applied development bias. In this case, it is preferable to use a magnetic carrier having a volume average particle diameter of 20 to 50 μm, preferably 25 to 40 μm, from the viewpoints of ensuring high image quality and preventing carrier adhesion.

[0044]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited thereto. The binder resins used in the following examples and comparative examples are as follows.

(Production Example of Polyester Resins A to G) In a glass four-necked flask equipped with a thermometer, a stirrer, a falling condenser, and a nitrogen inlet tube, an alcohol component and an acid component in the molar ratios shown in Table 1. Together with a polymerization initiator (dibutyltin oxide). This was reacted by heating in a mantle heater with stirring under a nitrogen atmosphere to obtain a number average molecular weight (Mn) shown in Table 1.
Polyester resins A to G having a weight average molecular weight / number average molecular weight (Mw / Mn), glass transition point (Tg), softening point (Tm), acid value and hydroxyl value were obtained. In Table 1, P
O is polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane, EO is polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, and GL is Glycerin, TPA
Represents terephthalic acid, TMA represents trimellitic acid, and FA represents fumaric acid.

[0046]

[Table 1]

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

The glass transition point was measured by a differential scanning calorimeter (DSC-
200; manufactured by Seiko Denshi Co., Ltd.)
0 mg was measured, and alumina was used as a reference, and the shoulder value of the main endothermic peak in the range of 30 to 80 ° C. was taken as the glass transition point.

For the softening point, use a flow tester (CF
T-500; manufactured by Shimadzu Corporation), a sample of 1.0 g was measured using a 1.0 mm × 1.0 mm die under the conditions of a temperature increase rate of 3.0 ° C./min and a load of 30 kg. Is the softening point when 1/2 flows out.

The acid value was obtained by dissolving the weighed sample in an appropriate solvent and expressing the mg of potassium hydroxide required to neutralize the acidic group using an indicator such as phenolphthalein.

The hydroxyl value was expressed in mg of potassium hydroxide required to hydrolyze an acetylated product obtained by treating a weighed sample with acetic anhydride and neutralize liberated acetic acid.

Example 1 A polyester resin A and a yellow pigment (CI Pigment Yellow 180) were charged and kneaded in a pressure kneader so that the weight ratio of resin to pigment was 7: 3. The obtained kneaded material was cooled and pulverized by a feather mill to obtain a pigment master batch.

93 parts by weight of polyester resin A, 10 parts by weight of the pigment masterbatch, 1 part by weight of a compound represented by the following formula (C):

[0054]

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After thoroughly mixing with a Henschel mixer,
The mixture was kneaded with a twin-screw extruder (PCM-30; manufactured by Ikegai Iron Works), and the cooled kneaded product was roughly pulverized with a feather mill. Thereafter, the coarsely pulverized product is pulverized with a mechanical pulverizer (KTM; manufactured by Kawasaki Heavy Industries, Ltd.) to a volume average particle size of 10 to 12 μm,
Further, after finely pulverizing with a jet pulverizer (IDS; manufactured by Nippon Pneumatic Industries Co., Ltd.) to a volume average particle size of 8 μm, a rotor type classifier (Tiplex classifier type 1
(00ATP; manufactured by Hosokawa Micron Co., Ltd.) to obtain yellow toner particles having a volume average particle size of 8.0 μm.

0.5 parts by weight of hydrophobic silica (TS-500, manufactured by Cabosil) and hydrophobic titanium dioxide (STT30A, manufactured by Titanium Industries) are added to 100 parts by weight of the toner particles.
1.0 part by weight was added and mixed with a Henschel mixer to obtain a yellow toner A.

Example 2 A yellow toner B was obtained in the same manner as in Example 1 except that the polyester resin A was changed to the polyester resin B.

(Example 3) In Example 1, the polyester resin A was changed to the polyester resin C, and the compound of the formula (C) was replaced with a compound represented by the following formula (D);

[0059]

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A yellow toner C was obtained in the same manner, except that the above conditions were changed.

Example 4 A yellow toner D was obtained in the same manner as in Example 1, except that the polyester resin A was changed to the polyester resin D.

Example 5 A yellow toner E was obtained in the same manner as in Example 1, except that the polyester resin A was changed to the polyester resin E.

(Example 6) In Example 2, an oxidized low molecular weight polypropylene wax (100TS; manufactured by Sanyo Chemical Industries, Ltd .; softening point 140 ° C; acid value 3.5 KOHmg /
g) Yellow toner F was obtained in the same manner except that 2 parts by weight was added.

(Comparative Example 1) In Example 1, the formula (C)
A yellow toner G was obtained in the same manner except that the compound was not added.

Comparative Example 2 A yellow toner H was obtained in the same manner as in Example 1, except that the polyester resin A was changed to the polyester resin F.

Comparative Example 3 A yellow toner I was obtained in the same manner as in Example 1, except that the polyester resin A was changed to the polyester resin G.

(Comparative Example 4) I.
Pigment Yellow 180 as C.I. I. A yellow toner J was obtained in the same manner except that the solvent was changed to Solvent Yellow 19.

(Comparative Example 5) I.
Pigment Yellow 180 as C.I. I. Pigment Yellow 133 except that the yellow toner K
I got

Comparative Example 6 In Example 1, C.I. I.
Pigment Yellow 180 as C.I. I. Pigment Yellow 169 except that the yellow toner L
I got

Comparative Example 7 In Example 1, C.I. I.
Pigment Yellow 180 as C.I. I. Pigment Yellow 62, and a yellow toner M was obtained in the same manner.

(Production of Cyan Toner, Magenta Toner and Black Toner) I. Pigment Yellow 180 as C.I. I. Pigment Blue 15
A cyan toner was obtained in the same manner except that the toner was changed to -3.

In Example 6, C.I. I. Pigment Yellow 180 as C.I. I. Pigment Red 184
A magenta toner was obtained in the same manner except that the above was changed.

In Example 6, C.I. I. Pigment Yellow 180 with carbon black (Mogal L;
Black toner was obtained in the same manner except that Cabot was used.

The following evaluations were performed on the toner described above, and the results are shown in Table 2.

(OHP Translucency and Color Reproducibility of Images with Different Dot Area Ratios) Using a full-color printer described below under normal temperature and normal humidity environment (25 ° C., 60% RH)
Dot area ratio 1 on a 150-line screen on a P sheet
Images of 00%, 50% and 20% were imaged, and the yellow color development when projected by an overhead projector was visually evaluated. A case of vivid color development was evaluated as 、, a case of slight color development was evaluated as Δ, and a case of no color development was evaluated as ×.

The full-color printer used for this evaluation has the structure shown in FIG. 1, and is driven by an organic photosensitive drum 10 (hereinafter, photosensitive body 10) which is driven to rotate in the direction of the arrow in the figure.
, Laser scanning optical system 20, full-color developing device 3
0, an endless intermediate transfer belt 40 that is driven to rotate in the direction of the arrow in the drawing, and a paper feed unit 60. Around the photoconductor 10, a charging brush 11 for charging the surface of the photoconductor 10 to a predetermined potential and a cleaner 12 for removing toner remaining on the photoconductor 10 are provided.

The laser scanning optical system 20 is a well-known type having a built-in laser diode, polygon mirror and fθ optical element, and its control unit includes cyan (C), magenta (M), yellow (Y), and black (BK). Each print data is transferred from the host computer. The laser scanning optical system 20 sequentially outputs print data for each color as a laser beam, and scans and exposes the photoreceptor 10. As a result, an electrostatic latent image for each color is sequentially formed on the photoconductor 10.

The full color developing device 30 includes C, M, Y, B
The four color developing units 31C, 31M, 31Y, and 31BK containing a one-component developer composed of K non-magnetic toner are integrated, and can be rotated clockwise about a support shaft 33 as a fulcrum. Each developing device includes a developing sleeve 32 and toner regulating blades 34a and 34b. The toner conveyed by the rotation of the developing sleeve 32 is
It is charged by passing through a pressure contact portion (restriction portion) between 4a and 34b and the developing sleeve 32.

The intermediate transfer belt 40 is rotated in the direction of the arrow in FIG. Intermediate transfer belt 40
Is pressed by the rotatable primary transfer roller 41 and the photosensitive member 1
0 is in contact. The intermediate transfer belt 40 is in contact with a rotatable secondary transfer roller 43 at a portion supported by a support roller 42.

Further, a cleaner 50 is provided in a space between the developing device 30 and the intermediate transfer belt 40. The cleaner 50 has a blade for removing residual toner on the intermediate transfer belt 40. The blade and the secondary transfer roller 43 can contact and separate from the intermediate transfer belt 40.

The paper supply unit 60 includes a paper supply tray 61 that can be opened to the front side of the image forming apparatus main body 1, a paper supply roller 62,
And a timing roller 63. The recording sheets S are stacked on a paper feed tray 61, fed one by one in the drawing by the rotation of a paper feed roller 62, and synchronized with an image formed on the intermediate transfer belt 40 by a timing roller 63. To the secondary transfer section. The horizontal transport path of the recording sheet is constituted by an air suction belt 66 and the like including the paper feed section, and a vertical transport path 80 provided with a transport roller is provided from the fixing device 70. Recording sheet S
Is discharged from the vertical conveyance path 80 to the upper surface of the image forming apparatus main body 1.

Here, the printing operation of the full-color printer will be described. When the printing operation is started, the photoconductor 10 and the intermediate transfer belt 40 are driven to rotate at the same peripheral speed, and the photoconductor 10 is charged to a predetermined potential by the charging brush 11.

Subsequently, exposure of the cyan image is performed by the laser scanning optical system 20, and an electrostatic latent image of the cyan image is formed on the photosensitive member 10. This electrostatic latent image is immediately developed by the developing device 31C, and the toner image is transferred onto the intermediate transfer belt 40 in the primary transfer section. Immediately after the end of the primary transfer, the developing device 31M is switched to the developing unit D, and then exposure, development, and primary transfer of the magenta image are performed. Further, switching to the developing device 31Y, exposure and development of a yellow image,
Primary transfer is performed. Further, switching to the developing device 31BK, exposure and development of a black image, primary transfer are performed, and
The toner image is superimposed on the intermediate transfer belt 40 every time the next transfer is performed.

When the final primary transfer is completed, the recording sheet S is sent to the secondary transfer section, and the full-color toner image formed on the intermediate transfer belt 40 is transferred onto the recording sheet S. When the secondary transfer is completed, the recording sheet S is conveyed to the belt-type contact heating and fixing device 70, where the full-color toner image is fixed on the recording sheet S and discharged to the upper surface of the printer body 1.

Incidentally, the image formation is carried out by the following method.
550 V, a developing bias voltage of -200 V, a primary transfer bias voltage of 900 V, and a secondary transfer bias voltage of 500 V. Under the setting conditions that the toner adhesion amount of the solid image portion on the recording sheet is 0.7 mg / cm ² , And fixing temperature 1
The test was performed at 60 ° C. In addition, the fog, hollow, and transfer properties described below were evaluated in a low-temperature, low-humidity environment (10 ° C., 15% R
H) and in a high-temperature and high-humidity environment (30 ° C., 85% RH), and the worse evaluation results are shown in Table 2.

(Fog) A character pattern having a B / W ratio of 5% was printed with a single color of yellow toner using the above-described full-color printer, and the obtained image was visually confirmed. A sample having no practical problem with fog was evaluated as Δ, and a sample having fog existing over the entire surface and having a practical problem was evaluated as x.

(Escape) Using the above-described full-color printer, a green “E” character in which yellow toner and cyan toner are superimposed is printed. The ones that have image loss but can recognize the green "E" character and have no practical problems. The ones with severe image loss and difficult to recognize the green "E" character. Was evaluated as x.

(Transferability) For an image printed with a single color of yellow toner using the above-described full-color printer, the ratio of the toner adhesion amount on the transfer paper to the toner adhesion amount on the photosensitive drum was determined. , 70
% Or more and less than 80% were evaluated as Δ, and those less than 70% were evaluated as x.

(Light fastness) With respect to an image printed with a single color of yellow toner using the above-described full-color printer, the image was irradiated with an ultraviolet ray for 30 minutes using an ultraviolet irradiation device. Those having no problem were evaluated as Δ, and those with large fading were evaluated as x.

(Heat resistance) 5 g of toner was placed in a 50 cc glass bottle, and the toner was allowed to stand at 55 ° C. for 24 hours. The toner was checked for cohesiveness. However, those which were easily loosened by external force were evaluated as △, and those which had aggregates and were not easily loosened by external force were evaluated as ×.

[0091]

[Table 2]

The yellow toner F obtained in Example 6 and the cyan toner, magenta toner and black toner obtained in the above-mentioned production example were subjected to 3000 full-color images having a B / W ratio of 6% using the above-mentioned full-color printer.
A printing durability test was performed on the sheets. For the image after the end of printing,
When the evaluation of fog, hollow spots and transferability was carried out, all the ranks were maintained as ○.

(Example of carrier production) Acid value 2 KOHmg / g
100 parts by weight of a bisphenol A-type polyester resin having a glass transition point of 60 ° C., 400 parts by weight of magnetic powder (EPT-1000; manufactured by Toda Kogyo), 5 parts by weight of carbon black (Ketjen Black EC; manufactured by Lion Yushi) After 2 parts by weight of silica and H2000 (manufactured by Hoechst) were sufficiently mixed with a Henschel mixer, they were melt-kneaded with a twin-screw extruder. The obtained kneaded material was cooled, coarsely pulverized with a feather mill, finely pulverized with a jet mill, and then finely classified with an air classifier. Thereafter, the suffocating system (SFS-1 type; manufactured by Nippon Pneumatic Co., Ltd.) is used.
Heat treatment was performed at 0 ° C. to obtain a carrier having a volume average particle size of 35 μm.

Next, an experiment was conducted using the developing apparatus shown in FIG. 2 when the yellow developer of the present invention was used as a two-component developer. As the developer, a yellow developer in which the yellow toner B and the carrier obtained in the above Production Example were mixed so that the toner concentration was 7% by weight was used.

In the developing device 100 shown in FIG. 2, the transport amount of the developer transported to the developing area is 4.5 mg / cm ² , Ds
0.35 mm, peripheral speed of photoconductor 102 120 mm / sec
c, the peripheral speed of the developing sleeve 111 is 300 mm / sec,
A photoreceptor surface potential of -450 V, a DC voltage of -350 V from the developing bias power supply 112, a rectangular wave having a peak and peak voltage of 1.4 KV and a frequency of 3 KHz, and du.
Reversal development was performed under a development bias in which an AC voltage having a ty ratio (development: recovery) of 1: 1 was superimposed. An image was formed on 10,000 sheets using the above yellow developer, and the images at the initial stage and after printing were evaluated for uneven density and fog. As a result, images free of uneven density and fog were obtained.

The configuration of the developing device of FIG. 2 used for the above evaluation will be briefly described. In the developing device 100, a developer 10 containing a toner T and a carrier therein is provided.
And a magnet roller 1 having a plurality of magnetic poles as a developer carrying member for carrying the developer.
A cylindrical developing sleeve 11 in which is fixedly disposed inside
1 is rotatably arranged. The developing sleeve 111 is disposed so as to face the negatively chargeable organic photoconductor 102 with a suitable distance Ds in the developing area.

The developing sleeve 111 is connected to a developing bias power supply
Then, a developing bias voltage in which a DC voltage is superimposed on an AC voltage is applied to apply an oscillating electric field to the developing region.

At a position facing the magnetic pole N1 of the magnet roller 110 on the upstream side of the developing area in the developer transport direction,
The magnetic blade 113 is provided at a predetermined interval from the developing sleeve 111, and the amount of the developer on the developing sleeve 111 is regulated by the magnetic blade 113.

Further, in the developing device 100, a toner storage portion 114 for storing the toner T is provided above the developing device 100. As a result of the development using the toner in the developer from the developing sleeve 111, the developing device 100 When the toner concentration in the developer inside the toner storage unit 114 decreases, the toner T is supplied by rotating a toner supply roller 115 provided below the toner storage unit 114. The supplied toner is mixed and stirred with the developer by the mixing and stirring member 116 and is supplied to the developing sleeve 111.

In the developing device 100, the amount of the developer on the developing sleeve 111 is regulated by the magnetic blade 113, and the developer is transported to the developing area in a thin layer state on the developing sleeve 111. A developing bias voltage is applied from 112 to cause an oscillating electric field to act on the developing area, and toner in the developer conveyed by the developing sleeve 111 is supplied from the developing sleeve 111 to the electrostatic latent image portion of the photoconductor 102 to perform development. I do.

[0101]

According to the present invention, a yellow developer having excellent translucency and color reproducibility can be obtained.

Further, according to the present invention, it is possible to obtain a yellow developer having excellent transferability even when forming a multicolor image.

Further, according to the present invention, it is possible to obtain a yellow developer applicable to a non-magnetic one-component developing system.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a full-color printer.

FIG. 2 is a schematic explanatory view of a two-component developing device.

[Explanation of symbols]

10: Photoreceptor drum, 20: Laser optical system, 30: Full color developing device, 40: Intermediate transfer belt, 60: Paper feeding means, 70: Fixing device.

Claims (4)

[Claims] 1. A yellow developer used for forming a full-color image for reproducing a multicolor image, wherein the yellow developer is a binder resin having an acid value of at least 1 to 30 KOH mg / g, a compound classified as Pigment Yellow 180, And the following general formula (A): (Wherein, R ₁ and R ₂ each represent a hydrogen atom,
To 5 alkyl groups or — (CH ₂ ) X COOR ₅ group (R ₅ represents a hydrogen atom or a lower alkyl group;
And R ₃ and R ₄ each represent a hydrogen atom, a halogen atom, an optionally branched alkyl group having 1 to 12 carbon atoms, or an aryl group. l is 4 ~
An integer of 8, m represents an integer of 0 to 4, and 1 + m represents 4 to 8
It is. A yellow developer comprising negatively-charged nonmagnetic toner particles containing the compound represented by the formula (1). 2. The glass transition point of the binder resin is 5
The yellow developer according to claim 1, wherein the yellow developer has a softening point of 5 to 75 ° C, a number average molecular weight of 2500 to 6000, and a weight average molecular weight / number average molecular weight of 2 to 8. 3. The yellow developer according to claim 1, wherein the yellow developer is a non-magnetic one-component developer. 4. The yellow developer according to claim 1, wherein the yellow developer is a two-component developer containing a magnetic carrier.