JPH07261459A - Color image forming method - Google Patents

Abstract

PURPOSE:To provide a color image forming method capable of giving a color image having a high gloss, less liable to a change of the gloss, excellent in color reproducibility and free from ghost and offsetting. CONSTITUTION:In this color image forming method by electrophotography, a full-color image is formed in a developing process using three kinds of color toners and a black toner by a developing device for forming a full-color image having three kinds of colors and black. A resin component in each of the color toners is a mixture of linear polyester (A) consisting of a bisphenol A-alkylene oxide adduct and terephthalic acid or fumaric acid with nonlinear polyester resin (B) consisting of a bisphenol A-alkylene oxide adduct, terephthalic acid, an aliphatic group substd. succinic acid deriv. and a tri- or tetrabasic acid or an alcohol monomer and not contg. a THF-insoluble component. Colorants are org. pigments each subjected to melt flushing treatment with the linear polyester A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method in a printer, an electrophotographic copying machine and the like, and more particularly to an output image which shows a stable glossiness by controlling the change of the glossiness with respect to the change of the image density of the output image. The present invention relates to an image forming method. The present invention relates to an image forming method particularly suitable for a digital printer and a digital copying machine that handle an image as a digital signal.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus using an electrophotographic method, an upper roll (heating roll) and a lower roll facing the front surface (toner image forming surface) and back surface of a recording material are used as fixing means. A heating roll fixing device having rolls (pressure rolls) and configured to heat these rolls to a predetermined temperature by a heat generating means such as a heater lamp is widely used. In the fixing system of the color image forming apparatus, it is important not only to fix the fixed toner on the recording material, but also to sufficiently melt the toner to make the toner surface have high gloss and to develop a desired color. Function is required. When the toner is sufficiently melted, offset is likely to occur, and therefore, the heating roll is required to have a high releasability. For this reason,
In a fixing device of a color image forming apparatus that has been generally used in the past, a releasing oil supply system is arranged in the vicinity of a heating roll, and a large amount of releasing oil is supplied to the heating roll to prevent the occurrence of offset. It has been deterred. For this reason, there is a problem that a large amount of releasing oil adheres to the output image, and it cannot be added by a pencil, ink, or the like, or its performance is insufficient, and the hand feels uncomfortable.

On the other hand, regarding the colorants of color toners generally used in color image forming apparatuses, the colorants are organic pigment-based ones which are excellent in light resistance, migration resistance and safety. Colorants are used. However, as a drawback of the organic pigment-based colorant, commercially available dry powder is difficult to disperse in the binder resin used in the toner, and the primary particles of the pigment in the toner remain as aggregates. The light transmittance, which is the most important characteristic of the full-color toner, is greatly deteriorated, and the color reproducibility and the light transmittance of the OHP film are greatly deteriorated. As an effective means for solving the drawbacks of this organic pigment-based colorant, Japanese Patent Application Laid-Open No. 4-2 / 1992
It has been proposed to use melt flushing pigments as described in Japanese Patent No. 42752. That is, a water-containing paste of an organic pigment is heated together with a binder resin, heated and mixed at a temperature of at least 100 ° C. or higher in a pressure kneader to remove water with a molten resin, and a resin in which an organic pigment is dispersed at a high concentration. After producing (called a melt flushing pigment), it is melt-kneaded and pulverized with a binder resin to produce a toner. By using this melt flushing pigment,
By controlling the dispersion unit of the pigment in the toner, the light transmittance and color reproducibility of the full-color toner can be greatly improved. Therefore, melt flushing pigment technology is used as a method for obtaining a toner having excellent light transmittance and good color reproducibility while improving the releasability, and the high gloss, high color development and low temperature fixability of a full color toner as a binder resin. A method of using a binder resin having an increased molecular weight within a range that does not deteriorate is adopted, but in this case, in the melt flushing step, the binder resin is sheared and mixed at a high concentration in the melt flushing process. The molecular weight changes greatly,
There is a problem that manufacturing stability deteriorates. For the above-mentioned reason, generally, the characteristics of the resin component of the toner used in the color image forming apparatus is that a resin having a relatively low molecular weight and a narrow molecular weight component is used. It is designed so that the viscosity characteristics change greatly and the toner is instantly in a molten state when passing through a heating roll. Further, as the heating roll, in general, a soft roll which has a mirror surface and is deformed by the unevenness of the toner is used in order to obtain a high quality and high gloss image.

Also, regarding the glossiness of the output image,
The recording material generally used in the electrophotographic color image forming apparatus is plain paper, and the plain paper has a Peck smoothness of 20.
Or around 50 (seconds), there are many irregularities on the surface, the fiber density is low, and there are many voids between the fibers. Therefore, the fixed toner flows into the voids between the fibers, and the glossiness of the output image is affected by the unevenness of the fibers. Therefore, the glossiness of the output image largely depends on the amount of toner on the recording material. If the amount of toner on the recording material is small, the fixed toner may flow into the voids between the fibers as described above. Although the glossiness of the output image is low, as the amount of toner on the recording material increases, the voids between the fibers are filled with the melted toner, and the effect of the soft heating roll, which has a mirror surface on the roll surface, also contributes to the output. The glossiness of the image is
It is known to have a linearly high gloss. However, a general color image is formed with a mixture of a portion having a low density, that is, a small amount of toner on the recording material and a portion having a high density, that is, a large amount of toner on the recording material. The configuration of the image forming apparatus has a drawback that a high gloss portion and a low gloss portion are mixed in one output image, which is not preferable. To solve this problem, for example,
In Japanese Patent Laid-Open No. 4-204566, as a measure for controlling the gloss of an output image, a black toner having a softening point higher than that of the three chromatic color toners, for example, by 10 ° C. or more is used, and the black toner is used as a final formed color. An image forming apparatus is disclosed that changes the gloss of an output image by forming and adjusting the undercolor removal ratio according to the desired glossiness. However, when the image forming apparatus having the configuration disclosed in Japanese Patent Laid-Open No. 4-204566 is used, it is necessary to reduce the undercolor removal rate when trying to obtain a high-gloss color image. However, there are disadvantages that the sharpness of the image is lowered, the toner consumption is increased, and accordingly, fixing defects such as offset are likely to occur. Further, in order to obtain a low-gloss color image, it is necessary to increase the undercolor removal ratio, and in a low saturation area, a low-gloss image can be obtained, but in a high saturation area ( The glossiness in the area (mainly composed of two kinds of chromatic color toner) remains high, and areas of high gloss and low gloss are mixed in one output image, which is not preferable.

On the other hand, when the output image is a translucent image, it is disclosed in Japanese Patent Laid-Open Nos. 62-232671 and 2-2.
No. 63642 and No. 3-38659,
There has been proposed a method of forming a transparent coat layer made of a resin on a transparent film image support. However, in these methods, the toner is taken into the transparent coat layer made of a resin, fine lines such as characters and lines in the image are compatible with the resin forming the surrounding transparent coat layer, and the sharpness of the image is reduced. However, there are drawbacks such that the number of images is reduced, an image is generated, the unevenness of the toner image is insufficiently reduced, the structure of the transparent film for OHP is complicated, and the manufacturing cost is increased.
Conventionally, an image is formed on a transparent film by using a color toner by the method described above, the image is fixed on the transparent film by a fixing device, and the image is projected on a screen by an overhead projector (OHP) or the like. However, when the image is projected, a low-density portion and a halftone portion of the image become an unclear blackened image, so that a pseudo contour may occur. In this phenomenon, the toner surface forming the image is sufficiently smoothed by the fixing device in the high density portion of the image, but in the low density portion and the halftone portion of the image,
It is considered that the unevenness of the toner surface remains and the light scattering by the unevenness adversely affects the image portion. In order to solve this problem, for example, Japanese Patent Laid-Open No. 59-59
Japanese Patent Laid-Open No. 184361 proposes a method of spraying a lacquer or the like on the surface of a toner image, but the toner is dissolved by a solvent, which causes problems such as a decrease in image sharpness, color unevenness, and contamination of non-image areas. Occur. In addition, JP-A-6
Japanese Patent Application Laid-Open No. 0-52861 proposes a method of coating a toner image with a laminate film.
Japanese Patent No. 36756 and Japanese Patent Publication No. 61-36762 propose a method in which a transparent film is superposed on a toner image, heat-rolled and fixed, and then the transparent film is peeled off. However, these methods have problems that the number of processing steps after image formation is large and that the toner image is destroyed when the transparent film is peeled off. Further, Japanese Patent Laid-Open No. 63-80273 proposes a method of fixing with a heat quantity such that the toner is sufficiently melted, but in the case of a color toner, in order to obtain color developability, in general, a fixing temperature near the fixing temperature is used. Viscosity characteristics change greatly with temperature changes,
If the fixing heat amount is increased more than necessary in order to reduce the unevenness of the toner surface in the low density portion and the halftone portion, there is a disadvantage that offset occurs in the portion where the toner amount is large.

On the other hand, regarding the exposure means of the color image forming apparatus, in the past, the laser beam was driven based on the image data obtained by converting the original image into a digital value in terms of gradation reproducibility and color reproducibility. It is common to use a laser exposure means, and based on image data, as two-dimensional information of a predetermined location on the photoconductor,
Binary information of ON / OFF is given. When recording a halftone image using such a method, an area modulation method has conventionally been used, in which the density control of each color is performed by changing the area of minute dots or lines using a halftone dot structure or a line structure. It's being used. This method is used in many digital electrophotographic printers and copying machines because the algorithm is relatively simple and the cost is low.
In particular, as described above, in the digital image forming apparatus using the area gradation method by the laser exposure means that drives the laser beam based on the image data obtained by converting the original image into digital values as the exposure means of the color image forming apparatus, Since there are conspicuous unevenness of the toner image due to the image structure of dots and lines in the low density part and the halftone part, the unevenness of the toner image surface in the low density part and the halftone part is likely to remain and the incident light There is a problem that pseudo contours are prominently scattered in the low-density portion and the halftone portion of the image.

[0007]

DISCLOSURE OF THE INVENTION The present invention is intended to solve the above-mentioned problems in the prior art. The object of the present invention is to provide a sufficiently high gloss as compared with the prior art. However, there is little change in gloss, excellent color reproducibility, the amount of release oil supplied to the heating roll can be reduced, and a color image without offset can be obtained. It is in. Another object of the present invention is to provide an image forming method capable of obtaining a color projection image which is superior in color reproducibility and gradation reproducibility and which is free from false contours and offsets by a simple method as compared with conventional techniques. To provide.

[0008]

The present invention provides at least the following:
A latent image forming step of forming an electrostatic latent image on a uniformly charged photoconductor by exposure, a developing step of developing the electrostatic latent image with toner, and a formed toner image transferred to a recording material. Then, in the color image forming method comprising a transfer separation step of separating from the toner developing / holding member and a fixing step of fixing the transferred toner image on a recording material, the developing step includes three types of chromatic color and black. A four-color full-color image forming developing device is used to form a full-color image using three types of chromatic color toners and black toners, and the three types of chromatic color toners forming an image are colored with at least a resin component. 90/10 to 10 by weight of the linear polyester (A) and the non-linear polyester resin (B), which is substantially free of tetrahydrofuran insoluble components, as the resin component.
/ 90, the colorant is an organic pigment melt-flushed with the linear polyester (A), and the linear polyester (A) has a weight average molecular weight of 40,000 or less. And a bisphenol A-alkylene oxide adduct as a dihydric alcohol monomer, and terephthalic acid or fumaric acid as a dibasic carboxylic acid monomer as essential components. (B) is weight average molecular weight (Mw) 100,000 or less, number average molecular weight (Mn)
3,000 or more, Mw / Mn is 5 or more, bisphenol A-alkylene oxide adduct as a dihydric alcohol monomer, terephthalic acid and an aliphatic group-substituted succinic acid derivative as a dibasic carboxylic acid monomer, It is characterized in that it is composed of a tribasic or tetrabasic carboxylic acid or a trivalent or tetravalent alcohol monomer as an essential component.

In the present invention, the full-color image formed on the recording material is formed by superposing four color toner images of the above three kinds of chromatic color toner and black toner, and a black toner image is formed in the lowermost layer. Preferably. Also,
In the present invention, the black toner forming an image is composed of at least a resin component and a colorant, and the resin component contains a tetrahydrofuran insoluble component obtained by polycondensing an alcohol monomer and a carboxylic acid monomer. First, the molecular weight and the molecular weight distribution of the toner resin component measured by gel permeation chromatography of the resin component are as follows: weight average molecular weight (Mw) 25,000 to 80,000, number average molecular weight (Mn) 2,000 to 10 2,000, weight average molecular weight / number average molecular weight (Mw / Mn) of 10 or more, and the temperature at which the apparent melt viscosity of the toner by the flow tester method becomes 1 × 10 ⁴ poise is preferably 115 to 140 ° C. . Further, according to the present invention, as an exposing means in the latent image forming step, a light beam generated by a laser light source, a beam scanning means for relatively scanning the light beam with respect to a photoconductor, and a light scanning means for condensing the light beam. It is preferable to apply the present invention to a color image forming method in which exposure is performed by a laser exposure system using a pulse width modulation system by using an exposure unit provided with an imaging optical system that forms a beam spot of a predetermined size on the body. Further, in that case, the beam diameter in the main scanning direction of the laser scanner: Db and the pixel pitch in the main scanning direction:
Exposure is preferably performed so that the relationship of Ds satisfies Db / Ds ≦ 0.8.

The present invention will be described below. First, the chromatic color toner and the black toner used in the present invention will be described. The chromatic toner is composed of at least a resin component and a colorant, and the resin component is a linear polyester (A).
And a non-linear polyester resin (B) substantially containing no tetrahydrofuran insoluble matter are mixed in a weight ratio of 90/10 to 10/90. The linear polyester (A) used in the present invention has a weight average molecular weight of 4
It is less than 10,000 and is composed of a bisphenol A-alkylene oxide adduct as a dihydric alcohol monomer, and terephthalic acid or fumaric acid as an essential component as a dibasic carboxylic acid monomer. The weight average molecular weight of the toner measured by gel permeation chromatography is 5,000 to 40,0.
00, especially 7,000 to 20,000, and a number average molecular weight of 1,000 to 5,000, especially 2,000 to 4,
Those in the range of 000 are preferable. When the molecular weight of the linear polyester (A) is larger than the above range, the molecular chain of the resin component is cut by shearing force during the production of the melt flushing pigment, and the molecular weight is significantly changed, resulting in poor toner production stability. become. On the other hand, when the molecular weight is smaller than the above range, the glass transition point of the resin component is lowered and the toner blocking property is deteriorated. Also,
The linear polyester (A) preferably has a temperature at which the apparent melt viscosity of the toner by the flow tester method becomes 1 × 10 ⁴ poise, in the range of 90 to 130 ° C., particularly 100 to 120 ° C. This temperature means the softening point of the resin component, and if the softening point is higher than the above range, the low temperature fixability becomes poor. Further, when the softening point is lower than the above range, the glass transition point of the resin component is lowered,
Toner blocking property deteriorates. Further, the glass transition point by differential thermal analysis is 50 to 80 ° C, particularly 55 to 70 ° C.
It is preferably in the range of.

Non-linear polyester (B) used in the present invention
Is a weight average molecular weight (Mw) of 100,000 or less, a number average molecular weight (Mn) of 3,000 or more, and Mw / Mn of 5 or more, and bisphenol A as a dihydric alcohol monomer.
-Alkylene oxide adduct, terephthalic acid and aliphatic group-substituted succinic acid derivative as dibasic carboxylic acid monomer, and tri- or tetra-basic carboxylic acid or trivalent or tetravalent alcohol monomer as essential components However, the toner has substantially no tetrahydrofuran insoluble matter and has a weight average molecular weight of 30,000 to 100,000, particularly 35,000 to 8 as measured by gel permeation chromatography.
And the number average molecular weight is 1,000 to 6,0.
00, particularly preferably in the range of 2,000 to 5,000. When the toner contains tetrahydrofuran-insoluble matter, the toner image on the transparent film is fixed, and when the image is projected, in the low-density portion and the halftone portion of the image,
An unclear blackened image is likely to occur, and pseudo contours are likely to occur. When the molecular weight is larger than the above range, the low temperature fixing property is poor and the fixing temperature rises, thus increasing the power consumption. Further, if the molecular weight is smaller than the above range, the releasability at the time of fixing the toner is reduced, and it becomes necessary to supply a large amount of releasable oil. The linear polyester (B) has a temperature of 90 to 140 at which the apparent melt viscosity of the toner by the flow tester method becomes 1 × 10 ⁴ poise.
It is preferably in the range of 100 ° C, particularly 100 to 130 ° C. This temperature means the softening point of the resin component, and if the softening point is higher than the above range, the low temperature fixability becomes poor. If the softening point is lower than the above range,
Since the glass transition point of the resin component decreases, the toner blocking property deteriorates. The glass transition point by differential thermal analysis is preferably in the range of 50 to 80 ° C, particularly 55 to 70 ° C.

The black toner used in the present invention comprises at least a resin component and a colorant, and the resin component does not contain a tetrahydrofuran insoluble component obtained by polycondensing an alcohol monomer and a carboxylic acid monomer. The toner resin component has a weight average molecular weight (Mw) of 25,000 to 80,000 and a number average molecular weight (Mn) of 2,000 to 10, as measured by gel permeation chromatography of the resin component. 000, weight average molecular weight / number average molecular weight (Mw / Mn) of 10 or more. When the resin component of the black toner contains tetrahydrofuran insoluble matter, it is difficult to obtain high gloss for a full-color image, and when the weight average molecular weight is larger than the above range, it is also difficult to obtain a high gloss image. . Further, if the weight average molecular weight is smaller than the above range, the releasability at the time of fixing the toner is reduced, and it becomes indispensable to supply a large amount of releasable oil. When the number average molecular weight is higher than the above range, the fixing temperature is increased, and therefore the power consumption is increased. If the number average molecular weight is smaller than the above range, the storage stability of the toner is deteriorated. Further, when the weight average molecular weight (Mw) / number average molecular weight (Mn) is smaller than 10, the glossiness of the output image linearly becomes high gloss in proportion to the toner amount, and it becomes difficult to obtain a low gloss image.

In each of the toners used in the present invention, the temperature at which the apparent melt viscosity of the toner by the flow tester method becomes 1 × 10 ⁴ poise is 115 ° C.
However, this temperature means the softening point of the resin component, and if this temperature is lower than 115 ° C., the releasability at the time of fixing the toner is low. When the temperature is lower than 140 ° C., fixing defects such as low temperature offset are likely to occur in the high density region. As for the softening point of the resin component, Shimadzu Flow Tester CFT500-A was used as a measuring device, and the measuring conditions were: die = 0.5 mm × 1.0 mm, heating rate = 5 ° C./mi.
n, load = 10 kg, preheating time = 300 sec, and measurement temperature range = 80 to 190 ° C. Further, the molecular weight of the resin component is measured by a fully automatic high temperature high speed chromatograph (WATERS ALC / GPC 1
50 C), tedrahydrofuran was used as a solvent, flow rate = 1.0 ml / min, temperature = 40 ° C., detector = differential refractometer (RI).

In the present invention, a polyester obtained by polycondensing an alcohol monomer and a carboxylic acid monomer is used as the polyester. In the linear polyester (A), as the divalent alcohol monomer, a bisphenol A alkylene oxide adduct is used as an essential component, but in addition, for example, ethylene glycol, diethylene glycol, triethylene glycol, Diols such as 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-butenediol, cyclohexanedimethanol, hydrogenated bisphenol A, and other divalent Alcohol can be used together. Further, as the dibasic carboxylic acid monomer, terephthalic acid or fumaric acid is used as an essential component. For example, maleic acid, mesaconic acid, citraconic acid,
Itaconic acid, glutaconic acid, phthalic acid, isophthalic acid,
Cyclohexanedicarboxylic acid, succinic acid, adipic acid,
Sebacic acid, malonic acids, alkyl succinic acid, acid anhydrides thereof, alkyl esters, and other divalent carboxylic acids can be used in combination. The non-linear polyester is non-linear one that does not generate tetrahydrofuran insoluble matter, and is trivalent or bisphenol A alkylene oxide adduct, terephthalic acid and an aliphatic group-substituted succinic acid derivative. It is prepared by using a tetravalent acid or a trivalent or tetravalent alcohol in combination. Examples of the trihydric and tetrahydric alcohols include sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, Glycerin,
Examples thereof include 2-methylpropanetriol, 2-methyl-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene and the like.

Examples of the tribasic and tetrabasic carboxylic acids include 1,2,4-benzenetricarboxylic acid,
1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, Others can be given.

In the present invention, the resin component in the chromatic toner is a mixture of the above linear polyester and non-linear polyester in the range of 90/10 to 10/90. When the ratio of the linear polyester to the non-linear polyester is larger than 90/10, the fluidity of the toner at the time of fixing and melting becomes large, so that the glossiness of the output image greatly depends on the toner amount of the recording material. This is not preferable for obtaining a uniform image, and offset is likely to occur. When the ratio of the linear polyester to the non-linear polyester is smaller than 10/90, the viscoelasticity of the toner at the time of fixing and melting becomes large, and a sufficient glossiness cannot be obtained on the recording paper. In a digital image forming apparatus using the area gradation method by means of a means or the like, pseudo contours due to the screen structure of dots or lines become prominent.

As the resin component of the black toner, those formed by condensation polymerization of the above-exemplified alcohol monomer and carboxylic acid monomer are used. Also in this case, as in the case of the chromatic toner, it is preferable to use two kinds of the above-mentioned linear polyester and non-battlefield potyester substantially containing no tetrahydrofuran insoluble matter. Further, the black toner preferably has a higher softening point than the three types of chromatic color toners, and in particular, the softening point of the black toner is 3
It is preferably higher than the softening point of the chromatic toners of 10 ° C. or more.

In the present invention, as the colorant for the chromatic toner, an organic pigment melt-flushed with the linear polyester (A) is used. As the colorant, monoazo yellow, disazo yellow, carmine,
Pigments such as quinacridone, rhodamine, and copper phthalocyanine can be used. In particular, C.I. I. Pigment Red-48: 1, C.I. I. Pigment Red-122,
C. I. Pigment Red-57: 1, C.I. I. Pigment Yellow-97, C.I. I. Pigment Yellow-1
2, C.I. I. Pigment Yellow-17, C.I. I. Pigment Blue-15: 1, C.I. I. Pigment Blue-
15: 3 or the like can be used. The melt flushing process may be performed by a known method. Carbon black, lamp black or the like can be used as the colorant for the black toner. The addition amount of these colorants is preferably in the range of 2 to 15 parts by weight with respect to 100 parts by weight of the binder resin. When the addition amount of the colorant is less than 2 parts by weight, the coloring power becomes weak, and when it is more than 15 parts by weight, the transparency of the color toner is deteriorated. Further, in the present invention, a colorless or pale color charge control agent which does not affect the color tone of the color toner may be added, if necessary. Examples of colorless or light-colored charge control agents include complexes such as boron-based complexes, chromium-based complexes and zinc-based complexes. The addition amount of the charge control agent is preferably in the range of 0.1 to 6 parts by weight with respect to 100 parts by weight of the binder resin.

Next, the image forming method of the present invention will be described. The image forming method of the present invention comprises at least a latent image forming step of forming an electrostatic latent image on a uniformly charged photosensitive member by exposure, a developing step of developing the electrostatic latent image with a toner, A transfer separation step of transferring the formed toner image to a recording material and separating it from the toner developing / holding member, and a fixing step of fixing the transferred toner image on the recording material, and
In the developing step, a full-color image is formed using the above-mentioned three types of chromatic color toner and black toner. Well-known magenta, cyan, and yellow color toners can be used as the three types of chromatic color toners. In the case of the present invention, the full-color image formed on the recording material is formed by superposing the toner images of the three types of chromatic colors and the black four colors, and the black toner image is formed in the lowermost layer. It is preferably developed.

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus for carrying out a color image forming method for carrying out the present invention. This image forming apparatus, as an exposure unit in a latent image forming step, collects a laser beam generated by a laser light source, a laser beam scanning unit that relatively scans the laser beam with respect to a photoconductor, and the laser beam. This is a type in which exposure is performed by a laser exposure system using a pulse width modulation system, using an exposure unit provided with an imaging optical system that forms a beam spot of a predetermined size on a photoconductor. Photoconductor 101 rotating in the direction of the arrow
A charging device 102, a rotary developing device 103, a transfer drum 104, a cleaner 105, a pre-exposure device 106, a potential sensor 108, and the like are arranged around the area. The photoconductor 101 is uniformly charged by the charger 102 in the dark portion. Beam exposure is performed on the photoconductor 101 by the laser beam scanning device 120, and an electrostatic latent image is formed. The laser beam scanning device 120 includes a semiconductor laser 121, a collimator lens 122, a polygon mirror 123, and an image forming optical system 1.
24 and the like. FIG. 2 shows a schematic configuration of the laser beam scanning device. In FIG. 2, the laser beam scanning device includes a semiconductor laser 221, a collimator lens 222, a polygon mirror 223, and an imaging optical system 224. The semiconductor laser 221 is a gradation based on a print signal from an image reading device or a computer. The signal is modulated by the light emission time control circuit 226 to be turned on / off, and the photoconductor 201 is controlled by a so-called pulse width modulation method.
To expose. FIG. 3 schematically shows the configuration of the light emission time control circuit shown in FIG. The triangular wave signal 301 is compared with the image signal 302 by the comparator 305, and the pulse width modulated laser drive signal 303 is generated. Figure 4
Shows the triangular wave signal 301 and the image signal 302 input to the comparator 305, and the laser drive signal 303 output from the comparator 305. Laser drive signal 303
Is a pulse signal in which the triangular wave signal 301 is amplitude-modulated by the image signal 302. The frequency of the triangular wave signal 301 corresponds to the image screen ruling.

The photosensitive member 101 rotates in the direction of the arrow and is uniformly charged by the charger 102 in the dark portion. Then, the laser beam modulated according to the image information of the first color is irradiated to expose the first color. Is performed, the photoconductor 10
An electrostatic latent image of the first color is formed on 1. Then, the electrostatic latent image of the first color on the photoconductor 101 is rotated by the rotary developing device 103.
Is developed with the toner of the first color to be visualized, and a toner image of the first color is formed. The rotary developing device 103 is composed of four developing devices having yellow, cyan, magenta, and black toners, respectively. In this example, each developing unit employs a reversal developing method using two-component magnetic brush development. An alternating electric field is applied to the rotary developing device 103 by a developing bias circuit (not shown). The developing bias circuit includes a high voltage AC power supply that supplies an AC bias and a high voltage DC power supply that supplies a DC bias.

The toner image of the first color thus formed on the photoconductor 101 is transferred onto the transfer drum 104 having the recording material 107 mounted on the outer periphery thereof. Transfer drum 104
Is rotated by the photosensitive member at a speed synchronized with the rotational speed of 101 while the first color toner image is held on the recording material 107. Meanwhile, the photoconductor 101 scrapes off the toner remaining on its surface with the cleaner 105, and then uniformly irradiates the surface with the pre-exposure device 106 to eliminate the non-uniform charge received by the optical memory or transfer. Then, the surface potential is set to about 0V. The photoconductor 101 repeats the second-color toner image formation process below charging by the charging device, and the second-color toner image is formed by the second-color development by the rotary developing device. Is transcribed to. By repeating this process, the transfer drum 104
After forming a multi-layered toner image on the upper surface and forming the toner image of the fourth color, the toner on the recording material 107 is separated from the transfer drum 104 by the peeling claw 104d, and then the fixing device 109.
To fix and form a multicolor image. Note that 104
a is a charging device for absorbing the recording material, 104b is a transfer device, and 104c
Is a peeling charger, and 104e is a discharging charger. In the present invention, it is preferable that the electrostatic latent image is formed, developed, and transferred in the order of black, yellow, magenta, and cyan. In that case, the toner image on the transfer material formed by development has a structure in which toner images of black, yellow, magenta, and cyan are superposed, and the black toner image is the lowermost layer.

The fixing device preferably used in the present invention comprises a heating roll and a pressure roll which rotate while being in pressure contact with each other, and a release mold for preventing toner offset on the outer peripheral surface of at least one of the heating roll and the pressure roll. A heating agent and a pressure roller, the toner image is fixed by passing through the sheet on which the unfixed toner image is formed. The pressure roll is a substrate roll having a heat source inside, an inner elastic body layer on which the metal-containing filler is dispersed provided on the substrate roll, and a single layer or multiple layers provided with the inner elastic body layer. And an external elastic body layer.

FIG. 5 is a schematic configuration diagram of an example thereof. The main part of the fixing device includes a heating roll 501 and a pressure roll 502. The heating roll 501 is composed of a substrate roll 504 having a Colts lamp 503 therein, an inner elastic body 505 provided thereon, and an outer elastic body 506 provided thereon. On the other hand, the pressure roll 502 includes a substrate roll 507 having a Colts lamp 518 inside, an inner elastic body 508 provided thereon,
And an outer elastic body 509 provided thereon. The heating roll 501 and the pressure roll 502 are pressed against each other by a heating mechanism (not shown). In addition, 513 is a release agent supplying means for applying the silicone composition 514 to the pressure roll 501. 515 is an oil pan, 516 is a supply roll, and 517 is a coating roll. Toner image 511
The recording material 510 carrying C is inserted between the heating roll 501 and the pressure roll 502 to be fixed.

Next, the materials used for the fixing device having the above structure will be described. The substrate roll that constitutes a part of the heating roll and the pressure roll requires high heat transferability and rigidity capable of transferring heat energy from a heating source provided inside these to the inner elastic body layer. It can be made of a metal material such as stainless alloy or aluminum.
Further, regarding the inner elastic layer provided on these substrate rolls, the elasticity and thickness capable of contacting the heating roll and the pressure roll with an appropriate pressing force and contact width to the sheet on which the toner image is formed, and the heating source Elastomers that require a high heat transfer property to transfer the heat energy of the above to the outer elastic layer, and specifically, a metal-containing filler is dispersed, such as fluorosilicone elastomer, silicone carbon elastomer, and various other silicone rubbers. , Fluoroelastomers, various organic rubbers such as ethylene / propylene / diene rubber, and various copolymers. Here, the upper limit of the rubber hardness of the elastomer forming the inner elastic layers of both rolls is 80 ° in JIS hardness, and generally 40 ° to 70 ° when the filler is dispersed.

On the other hand, the outer elastic layer provided on these inner elastic layers has a high heat transfer property capable of transferring the heat energy from the heating source to the toner image on the recording material, and toner offset prevention. Which requires affinity with the release agent and wear resistance, and as this constituent material,
Fluoroelastomers and silicone elastomers are preferred. As a specific example thereof, a fluoroelastomer is a copolymer of vinylidene fluoride and hexanefluoropropylene, which is commercially available as Viton.
n) What is known as A (trademark of EI DuPont), Viton B (trademark of EI DuPont), which is a terpolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene. Known as) and Fluorel 21
70, Fluorel 2174, Fluorel 2176, Fluorel 2177, Fluorel IVS76 (The above Fluorel is a product name of 3M Company), Viton GH, Viton EGO
C, Viton E430, etc. can be applied. Further, as a specific example of the silicone elastomer, a high temperature curing type (HT
V), room temperature curing type (RTV) or low temperature curing type (LT
V) etc. can be used. Further, in the case of a silicone elastomer, it is preferable to provide an oil resistant layer in the intermediate layer in order to prevent the release agent from entering the inner elastic body layer. Further, a mixture of a fluoroelastomer containing vinylidene fluoride as a main component and another material, for example, a mixture of tetrafluoroethylene, silicone rubber, fluorosilicone rubber or the like may be used. Examples of the metal-containing filler that appropriately adjusts heat conductivity include copper, tin, silver, zinc, aluminum, iron,
Metals such as lead, polybutene, platinum, gold, beryllium, nickel, chromium, iridium, ruthenium, tungsten, cadmium, vanadium, alloys of these metals, metal oxides, and metal salts thereof can be used.

In the present invention, the amount of releasing oil supplied to the heating roll is 30 μg / cm ² or less,
It is particularly preferably 20 μg / cm ² or less. The amount of oil is 3
When it is more than 0 μg / cm ² , the transfer to the recording material becomes remarkable, and the writing property is affected, and the presence of oil can be confirmed even by touch.

[0028]

The present invention uses, as the resin component of the three kinds of chromatic toner, two kinds of binder resins of the above specific linear polyester and a high molecular weight non-linear polyester substantially containing no tetrahydrofuran insoluble matter. As a result, while maintaining low-temperature fixability and high-temperature offset, the paper peelability from the fixing roll is improved, and in full-color images, the gloss is sufficiently high, but the change in gloss is small, and in full-color projected images, it is low. The unevenness on the surface of the toner image in the density portion and the halftone portion is reduced, and the pseudo contour does not occur in the projected image. Further, by using the above-mentioned specific linear polyester as the resin used for producing the melt flushing pigment, it is possible to eliminate the change in the molecular weight of the resin during the production of the melt flushing pigment and to secure the production stability. Furthermore, by using a melt flushing pigment, in addition to making it possible to make the pigment dispersion unit finer in the toner, the molecular weight change of the high-molecular-weight non-linear polyester due to the shearing force generated during the toner melt mixing is also improved. It can be lost. Further, in a full-color image formed by superimposing toner images of three types of chromatic colors and four colors of black, when the black toner image is formed in the lowermost layer, the black toner has low gloss characteristics. Even with the toner shown, the full-color image has a sufficiently high gloss and does not affect the gloss. Further, in the case of the black toner, as in the case of the resin components of the three types of chromatic toners, the two types of linear polyester having the above characteristics and high molecular weight non-linear polyester substantially containing no tetrahydrofuran insoluble matter are used. By using a binder resin, regardless of the order of image formation in a full-color image, the low-temperature fixability and the high-temperature offset are maintained, the paper peelability from the fixing roll is improved, and the full-color image has a sufficiently high gloss. , The change in gloss can be reduced.

[0029]

EXAMPLES The present invention will now be described with reference to examples. In the following examples, the color image forming apparatus shown in FIG. 1 was used to form an image under the following conditions. The photoconductor 101 is
In the dark area, the charger 102 is set to uniformly charge to -650 V, and the process speed is 160 m.
It was set to m / sec. Further, the four developing devices using the yellow, cyan, magenta, and black toners in the rotary developing device 103 employ the reversal development method using the two-component magnetic brush development, and the toner having an average particle size of 7 μm is used. Using. An alternating electric field is applied to the rotary developing device 3 by a developing bias circuit (not shown), but in this embodiment, a DC voltage −
An alternating electric field was applied under the conditions of 500 V, AC voltage 1500 Vp-p, and 6 KHz.

As the fixing device, the one having the structure shown in FIG. 5 was used. As heating roll 501, 500 inside
An inner elastic body 505 and an outer elastic body 506 provided on a substrate roll 504 formed of a core material made of aluminum and having an outer diameter of 43 mm were used. The inner elastic body is 100 parts by weight of silicone pound (SH841U, manufactured by Toray) and 100 parts by weight of crystalline silica and a vulcanizing agent (RC4, manufactured by Toray).
It was formed by filling and mixing with 0.8 part, the thermal conductivity λ was 0.0017 cal / cm sec deg, the rubber hardness was 60 ° in JIS hardness, and the approximate thickness was 3.0 mm. The outer elastic body is a viton rubber (E-60C,
It is formed by filling and mixing 100 parts by weight of DuPont), 2 parts by weight of carbon (made by Tokyo Materials Co., Ltd.) and 10 parts by weight of magnesium oxide (MgO: # 30, made by Kyowa Chemical Co., Ltd.), and its heat transfer coefficient λ. Is 0.005 cal / cm sec deg and the thickness is 20
was μm. On the other hand, as the pressure roll 502, 5
An inner elastic body 508 and an outer elastic body 509 provided on a substrate roll 507 formed of a core material made of aluminum and having an outer diameter of 49 mm were used, which were equipped with a 00 W Colts lamp 518. The inner elastic body is formed by filling and mixing 50 parts by weight of crystalline silica and 0.8 parts by weight of a vulcanizing agent (RC-4, manufactured by Toray) with 100 parts by weight of a silicone compound (SH841U, manufactured by Toray). The thermal conductivity λ was 0.0015 cal / cm sec deg, the rubber hardness was 70 ° in JIS hardness, and the approximate thickness was 1.0 mm. The outer elastic body was filled with 100 parts by weight of Viton rubber (E-60C, manufactured by DuPont), 2 parts by weight of carbon (made by Tokyo Materials Co., Ltd.), and 10 parts by weight of magnesium oxide (MgO: # 30, manufactured by Kyowa Chemical Co., Ltd.). The heat transfer coefficient λ was 0.005 cal / cm sec deg and the thickness was 20 μm. In addition, the heating roll 501 and the pressure roll 502
Means that a nip width of 6.0 mm is formed in the central portion by pressure contact by a heating mechanism (not shown), the surface temperature of the heating roll 501 is 165 ° C., and the surface temperature of the pressure roll 502 is 150 ° C. They are set so that they rotate in the directions of the arrows at a surface speed of 160 mm / sec. The amount of the releasing oil supplied to the heating roll was set to 20 μg / cm ² .

Next, the formulation of the developer used in the present invention will be shown. (Melt Flushing Pigment Production Method-1) (1) 100 parts by weight of linear polyester-A (bisphenol A-propylene oxide adduct / condensate of fumaric acid) Weight average molecular weight (Mw) = 13,000 Number average molecular weight (Mn ) = 2,700 weight average molecular weight (Mw) / number average molecular weight (Mn) = 4.
8 Glass transition temperature = 58 ° C. The apparent melt viscosity by the flow tester method is 1 × 10 ^4.
Poise temperature T T = 105 ° C. (2) Cyan pigment (CI pigment blue 15:
3) Water-containing paste Moisture content in water-containing paste = 30 wt% 62 parts by weight While melting and kneading the above (1) and (2) with a pressure kneader, water in the pigment-containing water paste is replaced with polyester A to remove water. A cyan flushing pigment a having a pigment content of 30 wt% was prepared.

(Melt Flushing Pigment Production Method-2) Cyan Pigment (CI Pigment Blue-15: 3) A water-containing paste was used as a magenta pigment (CI Pigment Red-
57: 1) Pigment content 30w in the same manner as in Melt Flushing Pigment Production Method-1, except that the water-containing paste was used instead.
A t% magenta flushing pigment b was prepared. (Melt flushing pigment production method-3) Melt flushing pigment production method-except that the cyan pigment (CI pigment blue 15: 3) water-containing paste was replaced with a yellow pigment (CI pigment yellow 17) water-containing paste A magenta flushing pigment c having a pigment content of 30 wt% was prepared in the same manner as in 1. (Melt Flushing Pigment Production Method-4) Linear polyester-A is added to non-linear polyester-B (bisphenol A
-Ethylene oxide adduct / bisphenol A-propylene oxide adduct / terephthalic acid / dodecenyl succinic acid / trimellitic anhydride condensate) Weight average molecular weight (Mw) = 83,000 Number average molecular weight (Mn) = 3,600 Weight average molecular weight (Mw) / number average molecular weight (Mn) = 23 Glass transition temperature = 62 ° C. Apparent melt viscosity by flow tester method is 1 × 10 ⁴
A cyan flushing pigment d having a pigment content of 30 wt% was produced in the same manner as in the melt flushing pigment production method-1, except that the temperature T for poise was changed to T = 130 ° C.

Each of these flushing pigments a, b, c and d was dissolved in tetrahydrofuran and the pigment constituents were removed to measure the molecular weight of the polymer. The flushing pigments a, b, and c had almost no change in comparison with the molecular weight and the molecular weight distribution of the raw material polyester-A, but the flushing pigment d was the raw material polyester-B.
The molecular weight and the molecular weight distribution were significantly different.

Example 1 (1) 30 parts by weight of the above linear polyester-A (bisphenol A-propylene oxide adduct / condensate of fumaric acid) (2) 70 parts by weight of the above non-linear polyester-B (bisphenol A-ethylene Oxide adduct / terephthalic acid / dodecenyl succinic acid / trimellitic anhydride condensate) (3) Cyan flushing pigment a 15 parts by weight With the above formulation, melt kneading with a pressure kneader, cooling, jet mill grinding, and classification A cyan toner A having a pigment content of 4 wt% and a volume average particle diameter of 7 μm was prepared. A magenta toner B having a pigment content of 4 wt% and a volume average particle size of 7 μm was produced in the same manner except that the cyan flushing pigment a was replaced with the magenta flushing pigment b. A volume average particle diameter of 7 μm with a pigment content of 4 wt% was obtained in the same manner except that the cyan flashing pigment a was replaced with a yellow flashing pigment c.
Yellow toner C was manufactured. The toner of each color and hydrophobic silica R812 (manufactured by Nippon Aerosil Co., Ltd.) were mixed using a high-speed rotary mixer, and further mixed with a 50 μm ferrite carrier coated with an acrylic polymer to prepare a developer of each color.

Example 2 (1) 50 parts by weight of the linear polyester-A (bisphenol A-propylene oxide adduct / condensation product of fumaric acid) (2) 50 parts by weight of the non-linear polyester-B (bisphenol A-ethylene Oxide adduct / terephthalic acid / dodecenyl succinic acid / trimellitic anhydride condensate) (3) Cyan flushing pigment a 15 parts by weight With the above formulation, melt kneading with a pressure kneader, cooling, jet mill grinding, and classification A cyan toner D having a pigment content of 4 wt% and a volume average particle diameter of 7 μm was prepared. A magenta toner E having a pigment content of 4 wt% and a volume average particle size of 7 μm was produced in the same manner except that the cyan flushing pigment a was replaced with the magenta flushing pigment b. A volume average particle size of 7 μm with a pigment content of wt% is the same as the cyan flushing pigment a except that the yellow flushing pigment c is used.
Yellow toner F was manufactured. The toner of each color and hydrophobic silica R812 (manufactured by Nippon Aerosil Co., Ltd.) were mixed using a high-speed rotary mixer, and further mixed with a 50 μm ferrite carrier coated with an acrylic polymer to prepare a developer of each color.

Example 3 (1) 70 parts by weight of the above linear polyester-A (bisphenol A-propylene oxide adduct / condensate of fumaric acid) (2) 30 parts by weight of the above non-linear polyester-B (bisphenol A-ethylene Oxide adduct / terephthalic acid / dodecenyl succinic acid / trimellitic anhydride condensate) (3) Cyan flushing pigment a 15 parts by weight With the above formulation, melt kneading with a pressure kneader, cooling, jet mill grinding, and classification A cyan toner G having a pigment content of 4 wt% and a volume average particle diameter of 7 μm was prepared. A magenta toner H having a pigment content of 4 wt% and a volume average particle diameter of 7 μm was produced in the same manner except that the cyan flashing pigment a was replaced with the yellow flashing pigment b. A volume average particle size of 7 μm with a pigment content of 4 wt% was similarly used except that the cyan flashing pigment a was replaced with a yellow flashing pigment c.
m yellow toner I was prepared. The toner of each color and hydrophobic silica R812 (manufactured by Nippon Aerosil Co., Ltd.) were mixed using a high-speed rotary mixer, and further mixed with a 50 μm ferrite carrier coated with an acrylic polymer to prepare a developer of each color.

Example 4 (Comparative Example) (1) 100 parts by weight of the above linear polyester-A (bisphenol A-propylene oxide adduct / condensation product of fumaric acid) (3) 15 parts by weight of cyan flushing pigment a After melt-kneading with a pressure kneader, the mixture was cooled, pulverized with a jet mill, and classified to prepare a cyan toner J having a pigment content of 4 wt% and a volume average particle diameter of 7 μm. A magenta toner K having a pigment content of 4 wt% and a volume average particle size of 7 μm was produced in the same manner except that the cyan flashing pigment a was replaced with the yellow flashing pigment b. A volume average particle size of 7 μm with a pigment content of 4 wt% was similarly used except that the cyan flashing pigment a was replaced with a yellow flashing pigment c.
m yellow toner L was prepared. The toner of each color and hydrophobic silica R812 (manufactured by Nippon Aerosil Co., Ltd.) were mixed using a high-speed rotary mixer, and further mixed with a 50 μm ferrite carrier coated with an acrylic polymer to prepare a developer of each color.

Example 5 (black toner) (1) 100 parts by weight of non-linear bisphenol polyester (bisphenol A-ethylene oxide adduct / bisphenol A-propylene oxide adduct / terephthalic acid / dodecenyl succinic acid / trimellitic anhydride condensate) ) Weight average molecular weight (Mw) = 83,000 Number average molecular weight (Mn) = 3,600 Weight average molecular weight (Mw) / Number average molecular weight (Mn) = 23 Tetrahydrofuran insoluble matter = 0% Apparent melting by the flow tester method Viscosity is 1 × 10 ⁴
Poisoning temperature T is T = 130 ° C. (2) 4 parts by weight of carbon black having a primary particle size of 45 μm Melted by an extruder with the above formulation, kneaded, cooled, and ground by a jet mill, The pulverized product was classified to prepare a black toner having a volume average diameter of 7 μm. Table 2 shows the molecular weight and the molecular weight distribution of the resin component of the black toner thus obtained. Further, the apparent melt viscosity of the black toner measured by the flow tester method is 1 × 10 ⁴
The poise temperature is also shown in Table 1. The toner of each color and hydrophobic silica R812 (manufactured by Nippon Aerosil Co., Ltd.) were mixed using a high-speed rotary mixer, and further mixed with a 50 μm ferrite carrier coated with an acrylic polymer to prepare a developer of each color.

Example 6 (black toner) (1) 70 parts by weight of non-linear bisphenol polyester (bisphenol A-ethylene oxide adduct / bisphenol A-propylene oxide adduct / terephthalic acid / dodecenylsuccinic acid / trimellitic anhydride condensate) ) Weight average molecular weight (Mw) = 83,000 Number average molecular weight (Mn) = 3,600 Weight average molecular weight (Mw) / Number average molecular weight (Mn) = 23 Tetrahydrofuran insoluble matter = 0% Apparent melting by the flow tester method Viscosity is 1 × 10 ⁴
The temperature T to be a poise is T = 130 ° C. (2) 100 parts by weight of linear bisphenol polyester-A (bisphenol A-propylene oxide adduct / condensate of fumaric acid) Weight average molecular weight (Mw) = 13,000 Average molecular weight (Mn) = 2,700 Weight average molecular weight (Mw) / Number average molecular weight (Mn) = 4.
8 Glass transition temperature = 58 ° C. The apparent melt viscosity by the flow tester method is 1 × 10 ^4.
Poisoning temperature T is T = 105 ° C. (3) 4 parts by weight of carbon black having a primary particle diameter of 45 μm Melted in an extruder with the above formulation, kneaded, cooled, and ground by a jet mill, The pulverized product was classified to prepare a black toner having a volume average diameter of 7 μm. Table 2 shows the molecular weight and the molecular weight distribution of the resin component of the black toner thus obtained. Further, the apparent melt viscosity of the black toner measured by the flow tester method is 1 × 10 ⁴
The poise temperature is also shown in Table 1.

Each color toner and hydrophobic silica R812
(Manufactured by Nippon Aerosil Co., Ltd.) was mixed using a high speed rotary mixer, and further mixed with a 50 μm ferrite carrier coated with an acrylic polymer to prepare a developer of each color.

Example 7 (black toner) (comparative example) (1) 100 parts by weight of linear bisphenol polyester (bisphenol A-propylene oxide adduct / condensate of fumaric acid) Weight average molecular weight (Mw) = 13,000 Average molecular weight (Mn) = 2,700 Weight average molecular weight (Mw) / Number average molecular weight (Mn) = 4.
8 Glass transition temperature = 58 ° C. The apparent melt viscosity by the flow tester method is 1 × 10 ^4.
Poisoning temperature T is T = 105 ° C. (2) 4 parts by weight of carbon black having a primary particle size of 45 μm The above components are melted in an extruder, kneaded, cooled and ground by a jet mill, and ground. The material was classified to prepare a black toner having a volume average diameter of 7 μm. With respect to the obtained black toner, Table 1 shows the molecular weight and the molecular weight distribution of the resin component constituting the toner. Further, the apparent melt viscosity of the black toner measured by the flow tester method is 1 × 10 ⁴
Table 2 also shows the poise temperature. The toner of each color and hydrophobic silica R812 (manufactured by Nippon Aerosil Co., Ltd.) were mixed using a high-speed rotary mixer, and further mixed with a 50 μm ferrite carrier coated with an acrylic polymer to prepare a developer of each color.

Using the developer (toner) shown in the above example, a toner image was formed on the recording material by the above-mentioned image forming apparatus, and the output image was evaluated. Table 3 shows the evaluation results at that time. The glossiness of the fixed image was measured by a glossiness meter (Glossguard II [incident angle 75 °], Gardner Glossmeter).

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

FIG. 6 shows the relationship between the toner image weight (TMA) and the glossiness of the magenta toner E (solid line) of Example 2 and the magenta toner K (dotted line) of Example 4.
Shown in. As shown in the evaluation results, the toners of Examples 1 to 3 did not cause offset even when the oil rate of the releasing oil supplied to the heating roll was reduced, and the toner had a low image weight (TMA) (TMA). : 0.7 mg / cm ² )
The difference in glossiness between time and high (TMA: 1.4 mg / cm ² ) was 10 or less, and the change in glossiness with respect to the change in TMA was small, and a good output image was obtained. On the other hand, the toner of Example 4 (Comparative Example) had a large change in glossiness with respect to the change in TMA, and in particular, an offset was generated by reducing the oil rate of the releasing oil.

Further, the cyan toner A, the magenta toner B and the yellow toner C shown in Example 1 are used as the three types of chromatic toners, and the black toners are Examples 5, 6 and 7.
Table 4 shows the evaluation results of glossiness and offset when the printing order was changed using (Comparative Example). The oil rate of the releasing oil at this time was 10 μg / cm ² .
In addition,

[Table 4] In Table 4, the printing orders A and B are as shown in FIG. Further, TMA: a is to yellow, magenta, respective colors of TMA cyan 0.12 mg / cm ^2, the TMA black and 0.36mg / cm ^2, TMA: b
Indicates that the TMA of each color of yellow, magenta, and cyan is 0.
25 mg / cm ² , 0.75 mg / cm of black TMA
² As shown in the evaluation results, when a black toner image is formed on the lowermost layer of the recording material, it is less affected by the black toner used, and the glossiness is similar to the evaluation results shown in Table 3 and the change in TMA. There was little change in glossiness with respect to, no offset occurred, and a good output image was obtained. Also,
When the toners of Examples 5 and 6 were used as the black toner, regardless of the printing order, the change in glossiness with respect to the change in TMA was small, and a good output image without offset was obtained.

Using the developer (toner) shown in Examples 1 to 4 above, a toner image was formed on the transparent film by the above-mentioned image forming apparatus, and the fixing speed was changed. (Offset) was evaluated. As the transparent film for OHP, an OHP film (V515) for a plain paper copying machine manufactured by Fuji Xerox Co., Ltd. was used, and the beam diameter and the pixel pitch were each 64.
μm and 127 μm. The evaluation results are shown in Table 5.

[Table 5] Evaluation 1: A natural image of a person or the like is formed on a transparent film,
When projected with FXOHPZ1 (manufactured by Fuji Xerox Co., Ltd.), it is evaluated as ◯ when a pseudo contour does not occur, and evaluated as x when a pseudo contour occurs. Evaluation 2: Offset in black composed of three colors of yellow, magenta and cyan (toner image weight: 2.1 mg / cm ² ).

Regarding the relationship between the 10-point average surface roughness (Rz) and the image input signal when the fixing speed is changed, the magenta toner single color of Example 1 (image input signal 1
The relationship of Rz to the image input signal at the image weight of toner at 00%: 0.7 mg / cm ² was investigated. OH
As the transparent film for P, an OHP film (V515) for a plain paper copying machine manufactured by Fuji Xerox Co., Ltd. is used.
Beam diameter and pixel pitch are 64 μm and 1 respectively
It was 27 μm. The result is shown in FIG. In addition, the projected image was evaluated when the relationship between the beam diameter Db in the main scanning direction of the laser scanner and the pixel pitch Ds in the main scanning direction was changed. The evaluation results are shown in Table 6. In addition, O
As the transparent film for HP, OHP film (V515) for plain paper copying machine manufactured by Fuji Xerox Co., Ltd. was used, and as the toner, the toner of Example 1 was used, and the fixing speed was 40 m.
m / s. The pseudo contour was evaluated by forming a natural image of a person or the like on a transparent film and projecting it with FXOHPZ1 (manufactured by Fuji Xerox Co., Ltd.).

[0050]

[Table 6] As the evaluation result, the fixing speed is 20mm / s, 40m
In the case of m / s, the maximum value of 10-point average surface roughness (Rz) is 4 μm or less, and the image structure of unevenness is controlled.
The toners Nos. 3 to 3 did not cause any offset or pseudo contour in the projected image, nor did they cause any offset, and a good projected image was obtained. However, the fixing speed is 80mm /
In the case of s, a pseudo contour occurred. On the other hand, Example 4
The toner of (Comparative Example) has a fixing speed of 20 mm / s,
When 40 mm / s, an offset was generated, and when the fixing speed was 80 mm / s, a pseudo contour was generated, and a satisfactory projected image could not be obtained.

[0051]

Since the image forming method of the present invention has the above-mentioned constitution, in the color image, a sufficiently high gloss output image can be obtained, the gloss change is small, and the color reproducibility is excellent. The amount of release oil used can be reduced, and a color image without offset can be obtained. Further, even in the digital image forming apparatus using the area gradation method using the laser exposure means, it is possible to obtain a color projection image which is excellent in gradation reproducibility of the OHP color projection image and in which pseudo contours and offsets do not occur.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of a color image forming apparatus used in an image forming method of the present invention.

FIG. 2 is a schematic configuration diagram of a laser beam scanning device.

FIG. 3 is a schematic configuration diagram of a light emission time control circuit of FIG.

FIG. 4 is an explanatory diagram illustrating a formation state of a pulse-width-modulated laser drive signal.

FIG. 5 is a schematic configuration diagram of a transfer device.

FIG. 6 is a graph showing a relationship between gloss of toner and image weight of toner.

FIG. 7 is a diagram showing a printing order of A and B in Table 4.

FIG. 8 is a graph showing the relationship between the surface roughness and the image input signal when the fixing speed is changed.

[Explanation of symbols]

101 ... Photosensitive member, 102 ... Charging device, 103 ... Rotational developing device, 104 ... Transfer drum, 105 ... Cleaner, 106
... Pre-exposure device, 107 ... Recording material, 108 ... Potential sensor, 1
09: fixing device, 120: laser beam scanning device, 12
1 ... Semiconductor laser, 122 ... Collimator lens, 12
3 ... Polygon mirror, 124 ... Imaging optical system, 501 ... Heating roll, 502 ... Pressure roll, 503 ... Colts lamp, 504 ... Substrate roll, 505 ... Inner elastic body, 506
Outer elastic body, 507 ... Substrate roll, 508 ... Inner elastic body, 509 ... Outer elastic body, 510 ... Recording material, 511 ... Toner image, 513 ... Release agent supplying means, 514 ... Silicone composition, 515 ... Oil pan 516 ... Supply roll, 5
17 ... Coating roll, 518 ... Colts lamp.

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display area G03G 15/08 507 L

Claims (2)

[Claims] 1. A latent image forming step of forming an electrostatic latent image by exposing on a uniformly charged photoreceptor, and a developing step of developing the electrostatic latent image with toner. In a color image forming method comprising a transfer separation step of transferring a toner image to a recording material and separating it from a toner developing / holding member, and a fixing step of fixing the transferred toner image on the recording material, the developing step comprises three types. The above-mentioned three types of chromatic color toners for forming an image are to form a full color image by using three types of chromatic color toners and black toners by a four-color full-color image developing device of four colors. But,
90/10 to 10/90 by weight ratio of a linear polyester (A) and a non-linear polyester resin (B) which is substantially free of tetrahydrofuran insoluble components and which comprises at least a resin component and a colorant. Of the organic polyester obtained by melt flushing the linear polyester (A), and the linear polyester (A) has a weight average molecular weight of 40,000.
The following is a non-linear polyester comprising a bisphenol A-alkylene oxide adduct as a dihydric alcohol monomer and terephthalic acid or fumaric acid as a dibasic carboxylic acid monomer as essential components. (B) is weight average molecular weight (Mw) 100,000 or less, number average molecular weight (Mn) 3,000 or more, Mw / Mn
Is 5 or more, bisphenol A-alkylene oxide adduct as a dihydric alcohol monomer, terephthalic acid and an aliphatic group-substituted succinic acid derivative as a dibasic carboxylic acid monomer, and tribasic or tetrabasic A color image forming method comprising a carboxylic acid or a trivalent or tetravalent alcohol monomer as an essential component. 2. As an exposing means in the latent image forming step,
A light beam generated by a laser light source, a beam scanning means for relatively scanning the light beam with respect to the photoconductor, and an imaging for condensing the light beam to form a beam spot of a predetermined size on the photoconductor 2. The color image forming method according to claim 1, wherein the exposure is performed by a laser exposure method using a pulse width modulation method using an exposure unit having an optical system.