JP3040604B2 - Color image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming method for forming a high-quality full-color image by an electrophotographic method applied to a color copying machine or a color printer.

[0002]

2. Description of the Related Art In an example of a method for forming a full-color image by electrophotography, for example, B (blue), G (blue), and G (color) are formed on a photoreceptor using an organic or inorganic photoconductive material.
(Green), R (red) and ND if necessary
(Neutral) or the like, and irradiates the obtained color separation light to form an electrostatic latent image for each color. These electrostatic latent images for each color are represented by Y (yellow), M (magenta), C ( The toner is sequentially developed with a color toner such as cyan (Cyan) and, if necessary, BK (black) to form a color toner image for each color. Next, the color toner images of the respective colors are superimposed and formed on a photoreceptor and then collectively transferred to a transfer body, or transferred to a transfer body every time a toner image is formed on the photoreceptor. Overlap on the body. Then, the color toner image superimposed on the transfer body is heat-fixed by a heating roller and a pressure roller to form a color image.

A color toner used in such an electrophotographic method is composed of particles formed by dispersing a dye or a pigment in a thermoplastic resin (binder resin), and has an average particle diameter of usually 5 to 5. 20 μm. When a color image is formed with such toner particles, a multilayer toner particle layer is required to secure a sufficient image density. However, when a color image is obtained with a multi-layered toner particle layer, light transmittance is deteriorated, and the color image is turbid, and has a disadvantage of lacking color tone and sharpness. In addition, when a color image is formed by a multi-layer toner particle layer, it is difficult to fix to a sufficiently smooth surface state even by melting and fixing by heating, resulting in unevenness in the surface vertical direction. However, such a color image has poor color reproducibility and glossiness as compared with general photographs and printing, and as a result, the color image quality is inferior.

[0004] In order to improve the image quality of such color images, a transparent resin layer is formed on an image supporting substrate in JP-A-63-92965, for example, from the viewpoint of imparting glossiness. Attempts have been made to improve this by embedding toner particles in the transparent resin layer with a heating roller.

[0005]

However, as a result of diligent studies by the present inventors, according to the above technique, a color image having a certain level of gloss and good image quality can be provided, Color turbidity occurs and lacks color tone and sharpness. In addition, since the heating and fixing method uses only the heating roller, the toner particles are not completely melted but are in the form of a rubber-like elastic body, and are elastically deformed by the pressure of the heating roller to become smooth, but the pressure is released. Then, the state is relaxed to the original state, and the surface state does not reach the same as that of the contacting heating roller, and the toner particles are in a raised state, and the gloss is impaired. Further, at the separation stage where the heating roller and the toner image are separated, the fused toner has adhesiveness with the heating roller, so that the fixed toner image is lifted by being pulled by the heating roller in a direction along the surface of the image. .

[0006] From the viewpoint of improving the above drawbacks, preventing color turbidity in a color image, and imparting gloss, it is necessary to minimize the amount of developed toner and suppress the rise of a toner image on the surface of a transfer member. Is preferred. However, on the other hand, if the amount of the developing toner is reduced, the image density is reduced, and the toner cannot be uniformly developed due to the shortage of the toner amount, and the toner particles are partially or entirely formed in the obtained color image. Many white backgrounds are present in between, and only a color image with low image density, which is inferior in color reproducibility and sharpness, can be obtained.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a color image forming method capable of forming a glossy high-quality color image. Another object of the present invention is to provide a color image forming method capable of forming a color image without causing color turbidity. Further, another object of the present invention is to provide
It is an object of the present invention to provide a color image forming method capable of forming a color image having excellent sharpness.

[0008]

An object of the present invention is to provide a color toner image formed by three or more color toners containing a thermosublimable dye on the surface of a transparent resin layer made of a thermoplastic resin. It can be achieved by a color image forming method characterized in that the image is transferred onto a transfer member, and is heated and melted by a belt-shaped heating member to be fixed.

Hereinafter, the present invention will be described in detail. In the present invention, by including a thermo-sublimable dye in the color toner particles, even if there is a particle gap of a white background that can not be sufficiently developed in the developing step, while fixing in the fixing step, Since the transparent resin layer corresponding to the white portion between the particles is dyed by the diffusion of the heat sublimable dye, color turbidity does not occur, and the image density can be improved and uniformity can be achieved. However, when the heat roller fixing method is used, the color image is improved to some extent but insufficient because the heat fixing time is short and diffusion of the heat sublimable dye is not sufficiently performed. Therefore, in the present invention, the toner is heated and melted and fixed by the belt-shaped heating member, thereby securing a sufficient heating and fixing time. That is, when heated by a belt-shaped heating member, the thermosublimable dye is sufficiently diffused to dye the white portion in the transparent resin layer of the transfer body, thereby preventing the occurrence of color turbidity, improving the image density, and achieving uniformity. Can be. In addition, the fixation is sufficiently achieved, the toner image is prevented from rising on the surface of the transfer member, and a color image having excellent gloss can be obtained.

The color toner used in the present invention contains a heat sublimable dye as a colorant. Examples of such a heat sublimable dye include the following monoazo dyes, anthraquinone dyes, naphthoquinone dyes, styryl dyes, naphthol dyes, thiazole dyes, quinophthalone dyes, pyridone dyes, and the like. . Note that carbon black may be used for the black toner. The content is 1 to color toner particles.
It is 10% by weight.

<Monoazo dye> Compound represented by the following formula (1)

[0012]

Embedded image (R ¹ and R ² each represent an alkyl group or an alkoxy group having 1 to 4 carbon atoms.)

<Anthraquinone-based dyes>
Compound represented by

[0014]

Embedded image (R ³ and R ⁴ each represent an alkyl group having 1 to 4 carbon atoms.)

[0015]

Embedded image (R ⁵ represents an alkylene group which may be substituted with an alkoxyalkyl group or an allyloxyalkyl group.)

[0016]

Embedded image (R ⁶ and R ⁷ each represent an alkyl group having 1 to 4 carbon atoms.)

<Naphthoquinone dye> Compound represented by the following formula

[0018]

Embedded image (R ⁸ and R ⁹ each represent an alkyl group having 1 to 4 carbon atoms.)

<Styryl dye> Compound represented by the following formula (6)

[0020]

Embedded image (R ¹⁰ and R ¹¹ each represent an alkyl group or an allyl group having 1 to 4 carbon atoms, and Z ¹ represents a hydroxy group, a cyano group or a halogen.)

<Naphthol dye> Compound represented by the following formula (7)

[0022]

Embedded image (R ¹² represents an alkyl group, an alkoxy group, or an allyl group having 1 to 4 carbon atoms, and R ¹³ represents an alkyl group, an alkoxy group, an allyl group, or a phenyl group substituted or unsubstituted with halogen.)

<Thiazole dye> Compound represented by the following formula (8)

[0024]

Embedded image (R ¹⁴ , R ¹⁵ , and R ¹⁶ each represent an alkyl group, an alkoxy group, or an allyl group having 1 to 4 carbon atoms, and Z ² represents a methyl group, an acetylamino group, or a formylamino group.)

<Quinophthalone dye> Compound represented by the following formula (9)

[0026]

Embedded image (R ¹⁷ represents a phenylene group or a naphthylene group, and Z ³ represents hydrogen or halogen.)

<Pyridone dye> Compound represented by the following formula

[0028]

Embedded image (R ¹⁸ represents a phenylene group or a naphthylene group, and Z ⁴ represents an alkylene group.)

The color toner used in the present invention is composed of a binder resin, a charge controlling agent and other property improving agents as required, in addition to the coloring agent composed of a heat sublimable dye. Further, it can be obtained by externally adding and mixing inorganic oxide fine particles as necessary.

As the binder resin, styrene-
Acrylic resin, styrene-butadiene resin, polyester resin and the like can be mentioned, but in order to improve the incompatibility with the transparent resin layer and to give the spread of the image after fixing and the sharpness of the boundary region, polyester is used. 50 resin
It is preferable to contain it in a proportion of at least% by weight.

As the charge control agent, a metal complex salt of a monoazo dye, a metal complex with a carboxylic acid compound, a quaternary ammonium salt compound, a nigrosine dye and the like can be used.

As the other property improving agent, wax having a melting point of 60 to 160 ° C., such as paraffin wax, polyethylene wax and polypropylene wax, can be used in a range not exceeding 10 parts by weight based on 100 parts by weight of the binder resin.

As the inorganic oxide fine particles, silica, titanium oxide, etc., which have been subjected to a hydrophobizing treatment with a silane coupling agent, can be added and mixed in a range not exceeding 5% by weight based on the toner.

The color developer used in the present invention is preferably a two-component color toner composed of a non-magnetic color toner and a magnetic carrier, from the viewpoint of improving fluidity, triboelectricity, developability, image reproducibility and the like. Color developers are preferably used. As the carrier, magnetic particles such as iron, ferrite, and magnetite, or coated magnetic particles obtained by coating the magnetic particles with a styrene-acrylic resin, a silicon resin, a fluorine resin, or the like may be used. it can.

Next, the structure of a transfer member having a transparent resin layer on the surface, which is used to transfer a formed color toner image to obtain a color image, will be described.

Paper, plastic, and the like are used as the base of the transfer member. As the resin constituting the transparent resin layer,
Styrene resins and styrene-acrylic copolymer resins can be mentioned. Monomers used to obtain such a resin include styrene, styrene monomers such as α-methylstyrene, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, dodecyl acrylate, acrylic Lauryl acrylate, 2-ethylhexyl acrylate, dimethylaminoethyl acrylate, diethylaminoethyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, dodecyl methacrylate, lauryl methacrylate, methacrylic acid-2- Examples include (meth) acrylate monomers such as ethylhexyl, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate. Further, it is preferable to impart crosslinkability from the viewpoint of preventing the color toner from being excessively embedded and securing the releasability from the belt. For example, divinylbenzene, diethylene glycol dimethacrylate, triethylene glycol A crosslinkable monomer such as methacrylate may be used at a ratio of 0.1 to 5.0% by weight based on all monomers. Further, in order to adjust the molecular weight so as not to cause gelation, a chain transfer agent such as dodecyl mercaptan can be used in a range not exceeding 20% by weight.

In the present invention, the styrenic resin,
When the transfer member is formed of a styrene-acrylic copolymer resin and fixed by a belt-shaped heating member, the resin is easily softened and toner particles are easily buried, and even in a molten state, the belt-shaped heating member is used. Has good releasability, and at the stage where the toner image is peeled off from the belt-shaped heating member, it is possible to prevent the image from being lifted up by the adhesion to the belt-shaped heating member and the image from being lost due to transfer.

The transparent resin layer in the transfer member used in the present invention is formed to a thickness of 20 to 200 μm, preferably 20 to 80 μm on the substrate surface of the transfer member. Is preferred. When the thickness of the transparent resin layer is less than 20 μm, when the color toner image is melted and fixed, it is not sufficiently embedded in the transparent resin layer, and the resulting color image lacks glossiness with many irregularities. On the other hand, when the thickness of the transparent resin layer exceeds 200 μm,
The color toner image and the transparent resin layer are easily transferred to the belt, resulting in image loss and unevenness on the surface, resulting in a poor image having poor glossiness.

The transparent resin layer can be formed by dissolving the resin in a solvent such as toluene, acetone, ethyl alcohol, methyl ethyl ketone, or tetrahydrofuran, coating the solution on the substrate of the transfer body, and drying.

In the color image forming method of the present invention, a color toner image formed on a photoreceptor formed by, for example, an electrophotographic method is transferred to a transfer body, and is heated, melted and fixed to form a color image. Using a transfer body having a transparent resin layer on the surface, embedding a color toner image in the transparent resin layer and fixing it with a belt-shaped heating member so as to dye the transparent resin layer corresponding to the white background between color toner particles Thus, a color image is formed.

According to this configuration, the surface of the transfer body on which the color toner image has been transferred is heated even during the conveyance by the belt, so that the surface is heated for a much longer time than the roller system. . Therefore, the transparent resin layer on the surface of the transfer member is sufficiently melted, and the toner particles are in a fluidized state and are permanently deformed and easily embedded, and the diffusion time of the heat sublimable dye is sufficiently ensured. Further, even when the belt-shaped heating member is separated from the belt-shaped heating member, the releasability of the belt-shaped heating member from the transfer member and the toner image is good, so that the image is not lost due to the lifting or transfer of the toner image. For this reason, the obtained color image is excellent in glossiness by preventing irregular reflection of illumination light, and can be a high-quality color image without the image adhering to the belt-shaped heating member.

FIG. 1 (a) shows the light reflection state when there is no transparent resin layer, and FIG. 1 (b) has a transparent resin layer, and the fixed color toner image is Figure 4 shows the light reflection situation according to the invention embedded in a layer. In FIG. 1, 1 is a transfer body, 1A is a transfer body base made of plain paper, 1B is a transparent resin layer, and 2 is a fixed color toner image. As is apparent from FIG. 1, when the fixed color toner image 2 is embedded in the transparent resin layer 1B (FIG. 1B), there is no light scattering and the reflectivity is good.
A color image having good gloss can be obtained.

FIG. 2 shows an example of a fixing device which can be suitably used for fixing a color toner image in the color image forming method of the present invention. This figure 2
In the fixing device, the color toner adhered on the transparent resin layer on the surface of the transfer body is heated and melted in the transparent resin layer by a belt-shaped heating member that moves below the member containing the heat source, and then cooled. Then, the belt-shaped heating member can be separated from the transfer member to form a color image. In FIG. 2, 1 is a transfer member, 2A is a color toner image, and 3 is a heating roll. The heating roll 3 has a heat source 6 such as an infrared lamp inside. The heating roll 3 is configured such that an elastic layer 5 of rubber or the like is provided on the outer periphery of a core 4 fixed to a rotating shaft. 7 is a pressure roll,
8a is an upper heat-resistant belt, and 8b is a lower heat-resistant belt.
These heat resistant belts 8a and 8b are configured by treating the surface of a heat resistant resin such as polyimide with a silicone resin. Reference numeral 9 denotes a release roll, and 10 denotes a pressure roll for the release roll 9. Reference numeral 11 denotes a separation claw of the transfer body 1 provided as needed, and reference numeral 12 denotes a forced cooling device provided as needed.

In the fixing device shown in FIG. 2, the transfer member 1 carrying the color toner image 2A is heated and conveyed by heat-resistant belts 8a and 8b moving below a member having a heat source 6.
The color toner image 2 </ b> A on the transfer body 1 is melted and fixed, and cooled by natural air cooling or a forced cooling device 12 so as to be hardly deformed. According to such a fixing device, a very smooth color image can be obtained.

In the color image forming method of the present invention,
Image exposure is performed on a photoreceptor to form an electrostatic latent image for each color, and the latent images are superposed and developed with toners of respective colors of Y, MC, and BK to form a color toner image. Is collectively transferred onto a transfer member, and is then heat-fixed to form a color image.

Hereinafter, the color image forming method of the present invention will be described more specifically. FIG. 3 is a sectional view of a color image forming apparatus that can be used in the method of the present invention, where K is an image reading unit, L is a laser writing unit, M is an image forming unit, and N is a paper feeding unit. The image reading unit K is a mirror 2
5 on which the carriage 5 and the halogen lamp 24 are mounted
2, a movable mirror unit 23 to which mirrors 26 and 27 are attached, a lens 30, and a color separation filter device 3.
2, a CCD 33 and an image processing device 34. The laser writing unit L includes a motor 41, a polygon mirror 42, and the like. The image forming unit M includes, for example, the organic photoreceptor 40, a pre-exposure lamp 45A, a scorotron charger 45B, an AC bias P1, and a DC bias P
Developing units 46Y, 46M, 46C filled with a developer containing negative toners of Y, M, C and BK to which No. 2 is applied
And 46BK, a transfer unit 47 for transferring the color toner image formed on the organic photoconductor 40 to the transfer body PA or PB at once, a separator 48, a fixing unit 55 for fixing the color toner image, and an organic photoconductor 40. And a cleaning device 49 for removing the toner remaining on the upper surface. The fixing device 55 has the same configuration as that shown in FIG. Paper feed section N
Is provided in the transfer unit 47 and the separator 48 with the sheet cassette 50A.
Or, it has sending rollers 51A and 51B for sending the transfer body PA or PB from 50B, and a timing roller 52.

The color image forming method of the present invention can be carried out as follows using the color image forming apparatus having the above-described structure. That is, the user turns on the start button, outputs an initialization signal to the image reading unit K via the control circuit, and outputs the initialization signal to the color separation filter device 32.
Is set to the B filter. Organic photoreceptor 40-1
At the rotation, the original 20 on the original platen 21 of the image reading unit K is optically scanned by the halogen lamp 24 of the carriage 22, and the mirror group 25, 26, 27 driven by the stepping motor and the color set with the B filter are set. The light image of the original is formed on the light receiving surface of the CCD 33 through the lens 30 via the separation filter device 32, and is converted into an electric signal. The obtained electric signal is converted into an image
In A, signal processing such as A / D conversion, shading correction, gradation correction, color conversion, ghost processing, and multi-value processing is performed, and the Y image signal, which is the first color signal, is sent to the next laser writing unit L. Output.

A laser beam oscillated from a laser light source is pulse-width-modulated by the Y image signal, rotationally scanned by a polygon mirror 42 rotationally driven by a motor 41, and bent by a mirror 44 via an fθ lens 43. Then, pre-exposure is performed by a pre-exposure lamp 45A in advance and image exposure is performed on the surface of the organic photoreceptor 40 to which uniform charging is imparted by a charger 45B, thereby forming an electrostatic latent image. Next, the electrostatic latent image is reversibly developed in a non-contact manner by a developing device 46Y to form a Y toner image. While holding the obtained Y toner image on the organic photoconductor 40,
Is passed under the cleaning device 49 separated from the surface of the organic photoconductor 4 to form the next M toner image.
Conveyed to the charger 45B with the second rotation of 0.

The surface of the organic photoreceptor 40 carrying the Y toner image is uniformly negatively recharged by the charger 45B, and then switched to the G filter in the color separation filter device 32, and the image reading unit K Next, the image exposure of the laser beam based on the M image signal which is the second color signal from the image processing device 34 is performed by the next scanning, and the organic photoconductor 40 is exposed.
An electrostatic latent image is formed thereon, and is subjected to non-contact reversal development by the developing unit 46M in the same manner as in the case of the developing unit 46Y, so that an M toner image is superimposed on the Y toner image.

Similarly, at the third and fourth times of the organic photosensitive member 40, image exposure of the laser beam based on the C image signal using the R filter, development by the developing device 46C, and BK image signal using the ND filter After the image exposure of the laser beam based on the above and the development by the developing unit 46BK, the color toner image is formed by superimposing the C toner image and the BK toner image on the Y toner image and the M toner image on the organic photoreceptor 40.

The obtained color toner image is fed out of the cassette 50A at the
The transfer is performed by the transfer device 47 on the transfer body PA conveyed to the transfer area via 1A and the timing roller 52 at a time. After the transfer member PA on which the color toner image has been transferred is separated from the organic photoconductor 40 by the separator 48, the transfer member PA is transported to the fixing device 55 by the transport belt 54, and is heated and fixed by the fixing device 55 (see FIG. 2). Thus, a color image is formed, and the sheet is discharged to a sheet discharge tray 57 by a sheet discharge roller 56.

[0052]

[Example 1]

<Preparation of Transfer Body> Styrene-acrylic copolymer resin composed of styrene-butyl acrylate copolymer (weight composition: 82:17) [weight average molecular weight 120,000, softening point 1
21 ° C., glass transition point (Tg): 56 ° C.] is dissolved in an acetone solvent at a concentration of 20% by weight, applied to A4 size plain paper by a wire bar, and dried, and a transparent resin layer having a thickness of 20 μm is formed. Was prepared.

<Preparation of Developer> 100 parts by weight of polyester resin 10 parts by weight of BK toner (carbon black) 3 parts by weight of polypropylene 3 parts by weight of the above materials are melt-kneaded, pulverized, and classified to obtain a BK toner having an average particle diameter of 9 μm. Was prepared.

5 parts by weight of a compound represented by the following formula (a) (for Y toner): 5 parts by weight of a compound represented by the following formula (for M toner): 5 parts by weight of a compound represented by the following formula (c) (For C toner) Y toner, M toner, and C toner having an average particle diameter of 9 μm were prepared in the same manner as the BK toner except that the amount was changed to 5 parts by weight.

[0055]

Embedded image

By mixing 5 parts by weight of each of the above four kinds of color toners and 95 parts by weight of a spherical ferrite carrier coated with a styrene-methyl methacrylate copolymer, a total of four kinds of full-color developers are obtained. Was.

Using these developers, a color image was formed by the color image forming apparatus of FIG. 3 equipped with the belt-shaped fixing device of FIG. The obtained color image had a high image density of 1.32, was a uniform image, had no color turbidity, and was excellent in sharpness. Also, the glossiness of an image measured at a measurement angle of 75 ° using a “UGS-300A variable-angle gloss meter” (manufactured by Nippon Denshoku Industries Co., Ltd.) is 83%, which is excellent in glossiness. The image quality was high without transfer to the heating member.

Comparative Example 1 The procedure of Example 1 was repeated except that a roller-shaped heating member was used instead of the belt-shaped heating member.
As a result, a part of the obtained image was transferred to the roller-shaped heating member to cause the image to be missing, and the uniformity and the sharpness were poor, and the gloss was 32% and the gloss was poor.

[0059]

As is apparent from the above invention, according to the color image forming method of the present invention, it is possible to obtain a high quality color image which is excellent in sharpness without color turbidity and excellent in glossiness.

[Brief description of the drawings]

FIG. 1A is an explanatory view showing a light reflection state when a transfer body having no transparent resin layer is used, and FIG. 1B is a diagram showing light reflection when a transfer body having a transparent resin layer is used. It is explanatory drawing which shows a reflection situation.

FIG. 2 is a cross-sectional view of an example of a fixing device that can be suitably used in the present invention.

FIG. 3 is a cross-sectional view of an example of a color image forming apparatus that can be used for performing the color image forming method of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 transfer body 1A transfer body base 1B transparent resin layer 2 fixed color toner image 2A color toner image 3 heating roll 4 core 5 elastic layer 6 heat source 7 pressure roll 8a heat resistant belt 8b heat resistant belt 9 peeling roll 10 pressure roll 11 separation claw REFERENCE SIGNS LIST 12 forced cooling device 20 document table 21 document 22 carriage 23 movable mirror unit 24 halogen lamp 30 lens 32 color separation filter device 33 CCD 34 image processing device 41 motor 42 polygon mirror 43 fθ lens 45A pre-exposure lamp 45B scorotron charger 46Y yellow development Device 46M Magenta developing device 46C Cyan developing device 46BK Black developing device 47 Transfer device 48 Separator 49 Cleaning device PA Transfer unit PB Transfer unit 55 Fixing unit K Image reading unit L Laser writing unit M Image formation N paper feed unit

Continuation of front page (56) References JP-A-50-143232 (JP, A) JP-A-63-63060 (JP, A) JP-A-63-92965 (JP, A) JP-A-2-263642 (JP) , A) JP-A-2-162383 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 13 / 01,15 / 01 G03G 13/20 G03G 15/20-15/20 102 G03G 7/00 G03G 9 / 08,9 / 09

Claims (1)

(57) [Claims] 1. A belt-like image forming apparatus comprising: transferring a color toner image formed by three or more color toners containing a thermosublimable dye onto a transfer member having a transparent resin layer made of a thermoplastic resin on a surface thereof; A color image forming method characterized by fixing by heating and melting with a heating member.