JPH0338660A - Image forming method - Google Patents

Abstract

PURPOSE:To obtain color mixture and distinctness with which an original is faithfully reproduced and to prevent offset on a heating roller from occurring by regulating a temperature difference at which the apparent melt viscosity of toner and a coating layer member becomes a specified value within an appropriate range and improving a fixing roller. CONSTITUTION:The temperature difference is controlled so that the temperature difference at which the apparent melt viscosity of the toner and the coating layer member is 10<5> poises may satisfy a formula: 3<T2-T1<40 (T1: a temperature at which the viscosity of the toner is 10<5> poises and T2: a temperature at which the viscosity of the coating layer member is 10<5> poises). Furthermore, a thermal roll fixing device having at least a rubber-like elastic layer and an offset preventing layer on a core bar as the fixing roll and having the rubber-like elastic layer on the core bar as a pressurizing roll is used. It is desirable to use silicone rubber and fluoro-rubber as the rubber-like elastic body used as the pressurizing roll and use fluororesin and silicone resin as the offset preventing layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image forming method, and more particularly to a color image forming method with good color mixing properties.

[Prior Art] Currently, color copying machines are gradually beginning to penetrate the market, and monochrome copying machines are being replaced by color copying machines. However, like television, photographs, and color printed matter,
People who are used to seeing more beautifully processed color images are not necessarily satisfied with the full-color electrophotographic images that are currently in practical use.

I see, “Journal of Electrophotography Society Vol. 26 No. 1 (1987)
At J.N.A., a technical approach has been taken to improve the image quality of electrophotography, and the application of this technology to color copying is also being considered. However, although the current level is approaching that of photography and printing, it has not yet reached the level of comparable quality. The greatest interest in color copying in electrophotography was when
The key is how to achieve perfect color mixing and faithful reproduction of fine lines.

Color image formation by full-color electrophotography generally requires 3
Colors are reproduced using toner of three primary colors: yellow, magenta, and cyan.

In this method, light from an original is passed through a color-separating light transmitting filter that has a complementary color to the toner color to form an electrostatic latent image on a photoconductive layer. Next, the toner is held on a support through development and transfer steps. Next, the above-mentioned steps are sequentially performed several times, and the toners are superimposed on the same support while registering, and a final full-color image is obtained by one-time fixing.

One of the decisive differences between electrophotography and printing is that in electrophotography, the main focus is on using plain paper as the image support, whereas in printing, the image support is determined depending on the original to be printed. It lies in being able to choose your body. In particular, in multicolor color printing using gravure printing or high-grade offset printing, the printing paper is carefully selected, and in most cases it is customary to use so-called coated paper, which has significantly reduced unevenness on the paper surface.

Plain paper commonly used in electrophotography has a Bekk smoothness of about 20 to 50 (seconds), has a relatively uneven surface, has a low fiber density, and has many voids between fibers. As a result, the toner after transfer may fall into the gaps between the fibers or be arranged non-uniformly due to the unevenness of the fibers.

Furthermore, in the case of color copying in which three colors or four colors of toner including black toner are superimposed, it is more susceptible to the effects of unevenness of paper fibers and gaps between fibers, and sufficient superposition cannot be achieved, resulting in a desirable color mixture. can't get it.

In other words, if the toner layer, which is the image surface, is smooth, the incident light enters the toner layer without causing diffuse reflection, and only a specific wavelength is absorbed and transmitted by the toner layer, and then light with a desired specific wavelength is transmitted. That's what we see. However, if the toner layer has a rough surface, there will be a lot of scattering of the incident light, making it impossible to obtain a sufficient amount of light inside the toner layer, resulting in a dull image with poor clarity, which is expressed as insufficient color mixing in terms of image quality. becomes.

Conventionally, in order to deal with these problems,
No. 2964 and Japanese Unexamined Patent Publication No. 63-92965 disclose techniques for providing a transparent resin layer on an image support. What should be noted in these methods is the softening point of the selected transparent resin. If the softening point of the resin is lower than that of the toner as in the above-mentioned publication, the toner itself will not undergo high-temperature offset when passing through a fixing device, especially a heated roll fixing device, but the resin layer provided on the support will undergo high-temperature offset. It is easy to cause inconveniences such as . Unexamined Japanese Patent Publication 1986
JP-A-232671 proposes using the same thermoplastic resin for the toner receiving layer and the toner.

Although the above method prevents the toner and the receiving layer from being offset separately, during the heating roll fixing, the toner is taken into the receiving layer, and the toner is particularly affected by characters and lines in the image where there is less toner. These thin lines are compatible with the resin constituting the surrounding receptor layer, resulting in apparent blurring and thickening of the upper characters, and a decrease in sharpness, resulting in image defects.

The above-mentioned publication states that it is a more preferable embodiment that the toner can be press-fitted and buried in the toner-receiving layer, and since the present inventors cited these as examples of inappropriateness, the publication does not apply to the present invention. The intention is very different from that.

Also, JP-A No. 48-81539, JP-A No. 50-8
Patent No. 1339 and other publications disclose techniques for electrophotographic films for toner transfer that have a resin layer on a plastic film, but all of these incorporate a matting agent into the resin layer, which is a deliberate attempt. The resin layer has been devised to have irregularities. The purpose of such a method is different from the method considered by the present inventors for forming a color image with excellent color mixing properties by overlapping several types of toner layers having smooth surfaces.

Color toners generally used for color copying have considerable sharp melt properties, and upon fixing, the shape of the toner changes to almost a molten state, resulting in favorable gloss and color reproducibility.

These effects, as stated in the 4th Non-Impact Printing Technology Symposium Proceedings P129~ (1987), are based on the fact that the viscosity term is more important than the elastic ring in the viscoelastic properties of the binder resin as the toner fixing property. It means.

That is, when heated, the toner behaves more like a viscous body, has increased thermal meltability, and can also provide gloss. but,
This type of binder resin design that emphasizes viscosity inevitably requires
This reduces the intermolecular cohesive force during hot melting, and increases the adhesion of the toner to the hot roll when passing through the hot roll fixing device.

In particular, it is extremely difficult to heat-roll a layered structure having a transparent coat layer on the image support and several toner layers in the soil layer.

When such a layered structure having a considerable thickness is heat-rolled, a large amount of heat is removed from the heat roll in one treatment, and the amount of heat supplied to the leading and trailing ends of the structure is significantly different. . Therefore, low-temperature offset easily occurs at the rear end of the structure due to insufficient heat. Furthermore, if the temperature of the thermal roll device is set high in advance, as described above, the toner itself does not have much elasticity, so high temperature offset is likely to occur at the leading end. However, when the present invention is used, the possible fixing range between the low-temperature offset and the high-temperature offset is much narrower than when fixing toner on plain paper. Therefore, there is currently a particular need for a hot roll fixing device with good offset resistance.

When silicone rubber rollers, which are often used in copying machines on the market, are used as fixing rollers, high-temperature offset occurs due to the inherent deterioration of the release properties of the silicone rubber surface due to repeated use, regardless of whether release oil is applied or not. It becomes easier. At the beginning of use for silicone rubber rollers,
Due to the smoothness and cleanliness of the roller surface, a certain degree of mold releasability can be maintained. However, the image area is large like a color image, and the amount of toner retained on the support is much larger than that of a black and white copy image. If this continues, the releasability of the roller will gradually decrease. The speed at which this mold releasability deteriorates is several times that of black and white copying.

Further, since the toner itself has almost no elasticity as described above, it is powerless in providing offset resistance. As a result, a toner film or granular deposits are formed on the roller surface after just a few thousand to tens of thousands of sheets, and a so-called high-temperature offset occurs, where the upper layer of toner on the image surface that passes through the heated roller is stripped off. do.

Various measures have been attempted for fixing devices and toner to solve or alleviate this problem, but it cannot be said that a sufficient solution has been achieved yet.

As the fixing device, a material with excellent surface releasability is used. Alternatively, some methods have been devised, such as applying oil to the roller, and most of the thermal roller fixing devices of copying machines currently on the market use some form of oil application. However, applying a large amount of oil to improve mold releasability causes undesirable problems such as oil stains on the sheet and increased cost.

In addition, in order to improve mold releasability, low-molecular weight polyethylene or wax that melts sufficiently when heated is added to the toner, but although it is effective in preventing offset, it is difficult to add a large amount to the color toner. Adverse effects such as impairing the transparency of OHP images, unstable charging characteristics, and decreased durability have also been observed, and it is difficult to say that these are sufficient.

[Problems to be Solved by the Invention] As described above, the present invention is capable of faithfully reproducing an original, obtaining excellent color mixing properties and sharpness, in forming a full-color image by overlapping toners, and using a heated roll. An object of the present invention is to provide an image forming method in which offset does not occur when a fixing device is used.

In other words, an image support with a transparent coat layer that increases offset resistance without impairing the color reproducibility and gloss of color copied images, and a hot roll fixing device with high mold releasability and high durability. The aim is to provide new combinations.

[Means and effects for solving the problems] The present invention is characterized in that a toner image is formed on a transparent coat layer provided on an image support, and the support having the toner image is fixed with a hot roll. In the image forming method, the difference in temperature at which the apparent melt viscosity of the toner and coating layer member becomes 10'Voice is the following formula (%).As a fixing roll, at least a rubber-like elastic layer and a An image forming method characterized by using a hot roll fixing device having an offset prevention layer and having a rubber-like elastic layer on a core bar as a pressure roll.

In the hot roll fixing method, when the image support passes through the hot roll, it is generally understood that fixing is possible when the apparent melt viscosity of the toner on the support is 108 voices or less. The temperature of the heating roll is appropriately selected depending on the paper feeding speed, paper size, and toner meltability. However, if the temperature setting is low and the toner melt viscosity is 10'voice or more, the toner may not be formed on the image support. is not sufficiently fixed and easily peels off due to weak rubbing or bending, resulting in poor fixing.

However, the present inventors focused on the temperature at which the apparent melt viscosity of the toner and coating layer member becomes 10' poise, which is considered to be the critical viscosity at which the toner is fixed, and completed the present invention.

If the temperature difference between the toner and the coat layer member at which the 10' voice is obtained is 3 or less, the toner and the coat layer member will be compatible and integrated when passing through the fixing roll, which will impede the reproducibility of fine lines as described above. . If it is 40 or more, the coating layer member will not be thermally deformed at all when passing through the roller, so sufficient adhesion between the toner and the coating layer will not be obtained, and the toner will peel off due to scratches such as fingernails. . This is particularly noticeable when color toner is deposited in a layered manner.

Therefore, the preferable range of the difference between the temperatures TI and T2 between the toner and the coat layer member is 5<T, -T, <35, and more preferably 8<T, -T, <27.

As the toner and coat layer member used in the present invention, general transparent thermoplastic resins can be used.

For example, polystyrene, chloropolystyrene, poly-α-
Methylstyrene, styrene-chlorostyrene copolymer,
Styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-
Vinyl acetate copolymer, styrene-maleic acid copolymer,
Styrene-acrylate copolymer (styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-phenyl acrylate) copolymer), styrene-methacrylate ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methacrylate copolymer)
Styrene-type resins such as butyl methacrylate copolymer, styrene-phenyl methacrylate copolymer), styrene-α-methyl chloroacrylate copolymer, and styrene-acrylonitrile-acrylic ester copolymer (styrene or styrene substituted homopolymers or copolymers containing
, vinyl chloride resin, styrene-vinyl acetate copolymer, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, low molecular weight polyethylene, low molecular weight polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene- There are ethyl acrylate copolymers, xylene resins, and polyvinyl butyral resins. Particularly preferred resins for the color toner of the present invention include styrene-acrylic acid ester resins and polyester resins.

In particular, the following formula (wherein R is ethylene or propylene group, x, y
are each a positive integer of 1 or more, and the average value of x+y is 2 to 10. ) as a diol component, and a carboxylic acid component consisting of a divalent or higher carboxylic acid, its acid anhydride, or its lower alkyl ester (for example, fumaric acid, maleic acid, maleic anhydride, Phthalic acid, terephthalic acid,
A polyester resin obtained by cocondensation polymerization with at least trimellitic acid or pyromellitic acid is preferred.

In addition, a particularly noteworthy improvement in the thermal roll fixing device of the present invention is that it applies enough pressure to transfer sufficient heat to the overlapping color toner layer on the image support, which has a fairly thick transparent coat layer. The heat roll itself does not bend or warp even when the color is applied, ■The heat roll has enough elasticity to wrap the color toner layer on the roll surface, and even after repeated color copying, the roll surface remains unchanged. The mold releasability of the product is maintained.

That is, the configuration of the heat roll includes a two-layer or three-layer fixing roll having at least a rubber-like elastic layer on a core metal, and an offset prevention layer formed on the upper layer;
This is a combination of a pressure roll having a rubber-like elastic layer on a core metal.

Examples of the rubber-like elastic body used for the pressure roll and fixing roll include silicone rubber, polybutadiene rubber, polychloroprene rubber, fluororubber, acrylic rubber, polyisoprene rubber, urethane rubber, butadiene styrene rubber, and the like. .

In particular, the rubber-like elastic body for the fixing roll is vulcanized silicone rubber) (TV silicone rubber (high temperature vulcanization),
LTV silicone rubber (low-temperature vulcanization) and RTV silicone rubber (room-temperature vulcanization) are preferred, and their thickness is 0, :) to 5.
．． 0 mm, preferably 0.3 to 4.0 mm.

When the thickness is 5.0 mm or more, heat transfer from the core metal becomes poor, and the fixing roll tends to be delayed in returning to a predetermined temperature after the image support with the transparent coat layer containing the toner passes through the heated roller. increases. If it is less than 0.2 mm, the elasticity of the fixing roll decreases and the effect of enveloping the color toner is drastically reduced, resulting in poor color reproducibility and gloss, even when the image support having the transparent coat layer of the present invention is used. It cannot be used as a color copy image.

In addition, as a rubber-like elastic body used for the pressure roll,
Silicone rubber and fluororubber are preferred, and a thin film of fluororesin or fluorine latex may be provided on the surface for the purpose of maintaining better mold releasability.

The thickness of the pressure roller is 0.2 to 9.5+am, preferably 0.5 to 8.0 mm.

Examples of the anti-offset layer on the surface layer of the rubber-like elastic body in the fixing roll include fluororesin, styrene resin, acrylic resin, polyester resin, styrene-acrylic resin, epoxy resin, urethane resin, polyethylene resin, and polypropylene resin. Furthermore, in consideration of reducing surface energy and mold releasability, fluororesin and silicone resin are preferable, and in consideration of application of silicone oil to the fixing roll, silicone resin is particularly preferable.

The thickness of the resin is an important factor determining the durability of the fixing roll, and is preferably 10.0 to 100.0 μm, preferably 15.0 μm. (1~loo, o#Lm. If the thickness is less than 10.0 g, scratches and peeling of the resin surface will occur after just a few dozen copies, and there is no durability at all. Also, if the thickness exceeds 100, the resin This is not preferable because it impairs the effect of the rubber-like elastic material in the lower layer and deteriorates the adhesiveness.

As the image support, paper, cloth, polyester film, vinyl chloride film, butadiene film, polyvinylidene fluoride film, etc. can be used.

The thickness of the transparent coat layer is in the range of 10 to 500 pm, preferably 25 to 300 μm. In particular, when paper or cloth is used as the image support, the thickness must be sufficient to cover the irregularities and pores of the support. It is.

Colorants compatible with the toner of the present invention include the following pigments or dyes. In addition, in the present invention, C, 1, Disperse Y164. which has poor light resistance. C.I.

5olvent Y77 and C, 1,5olvent
Colorants such as Y93 cannot be recommended.

Examples of dyes include C,1, Direct Red 1, C.
,1, Direct Red 4, C,1, Acid Red 1
, C:, 1. Basic Red 1, C, 1, Modern Red 30, C, 1, Direct Blue 1. C,1
, Direct Blue 2, C, 1, Acid Blue 9, C
,1, Acid Blue 15, C,1, Basic Blue 3, C,I.

There are basic blue 5, c, r, and modern blue.

Pigments include Naphthol Yellow S, Hansa Yellow G, Permanent Yellow NCG, Permanent Red 4R, Pyrazolone Orange, Benzidine Orange G,
Permanent Red 4R, Watching Red Calcium Salt, Brilliant Carmino 3B, Fast Violet B, Methyl Violet Lake, Phthalocyanine Blue Fastest Sky Blue Indan Stremburu-BC
There is.

In particular, the pigments are preferably disazo yellow, insoluble azo, and copper phthalocyanine, and the dyes are preferably basic dyes or oil-soluble dyes.

Particularly preferably C,L pigment yellow 17, C,1
, Pigment Yellow 15, C,1, Pigment Yellow 13, C,1, Pigment Yellow 14, C,1, Pigment Yellow 0-12, c, r, Pigment Red 5
,C,I.

Pigment Red 3, C, 1, Pigment Red 2, C
, 1, Pigment Red 6, c, r, Pigment Red 7, c, r, Pigment Blue 16, C, 1, Pigment Blue 16, or having 2 substituents on the phthalocyanine skeleton having the structural formula (1) shown below. These include copper phthalocyanine pigments with ~3 substitutions.

Structural formula (1> Dye: C,1, Solvent Red 49, C,1,
Solvent Red 52, C, 1, Solvent Red 10
9, c, r, Paysic Red 12, c, r, Paysic Red 1, C,1, Paysic Red 3b.

In the present invention, the apparent viscosity and gloss were determined according to the following method.

Apparent viscosity measurement: Flow tester model CFT-500 (manufactured by Shimadzu Corporation) is used. The sample is a 60rnesh pass product with a rating of approximately 1.0 to 1.5
Weigh g. Use a molding machine to make this into 100kg/cm
Pressure is applied for 1 minute with a load of 2. This pressurized sample was processed under the following conditions at room temperature (temperature: about 20-30℃, humidity: 30-30℃).
70% RH) to obtain a temperature-apparent viscosity curve. From the obtained smooth curve, the temperature at which the apparent viscosity becomes lOs is determined.

RATE TEMP 6. OD/M ('C
1 minute) SET TEMP 70. O.D.
EG ('C)MAX TEMP 200
．． ODEGINTERVAL 3. ODE
GPREHEAT 30f), OSEC (sec) LOAD 20.0 KGF (
kg) DIE (DIA) 1.0 M
M (mm) DIE (LENG) 1
．． 0 MMPLUNGER1, OCM” (cm2)
Glossiness measurement: Measurement is performed using a VG-10 type glossmeter (manufactured by Nippon Kishoku), using each solid image used for chromaticity measurement as a sample image.

For the measurement, first set the voltage to 6⁻ using a constant voltage device. Next, the light emission angle and light reception angle are each adjusted to 60''.

Using a zero point adjustment and a standard plate, place the sample image on the sample stage after setting the standard, then stack three sheets of white paper on top, perform measurement, and read the value shown on the indicator in % units.

At this time, set the S and S/10 switching SW to S, and set the angle to 9 IC.
Set the 3-degree switch SW to 45-60.

A trial image density of 1.5±0.1 is used.

Hereinafter, the present invention will be explained in detail with reference to Examples.

[Example] A color toner was obtained using 100 parts by weight of a polyester resin obtained by condensing eupropoxylated bisphenol and fumaric acid with the following prescribed amounts of a colorant and a charge control agent.

(Left below) A mixture containing a predetermined amount of each of the above components is sufficiently premixed using a Henschel mixer, melted and kneaded at least twice using a three-roll mill, and after cooling is coarsely ground using a hammer mill to about 1 to 2 mm. Then, it was pulverized to a particle size of 40 μm or less using an air jet type pulverizer.

Further, the obtained finely pulverized product was classified, and a classified product was obtained by mainly selecting 2 to 20 μm so that the average particle size was 8 μm. A color toner was prepared by externally adding 0.5 parts by weight of silica fine powder treated with hexamethyldisilazane as a fluidity improver to 100 parts by weight of each classified product.

Vinylidene fluoride-tetrafluoroethylene copolymer (copolymerization weight ratio 8:2) and styrene-2-ethylhexyl acrylate-methyl methacrylate (copolymerization weight ratio 45:20) are added to 4 to 6 parts by weight of this color toner.
: 35) at a weight ratio of 50:50, approximately 0.5% by weight
The coated Cu-Zn-Fe-based ferrite carrier (average particle size 48 μm; 250 mesh pass 350 mesh pass 79% by weight; true density 4.5 g/cm3) was mixed in a total amount of 100 parts by weight to prepare a two-component developer. . In consideration of color reproducibility and toner scattering, developer concentrations of yellow, magenta, cyan, and black color toners were set to 4% by weight, 5% by weight, 6% by weight, and 5% by weight, respectively.

A copying test was conducted using a color electrophotographic apparatus having an OPC photosensitive drum and a replenishment/development system shown in FIGS. 1 and 2.

Development and transfer of each color toner is magenta toner.

Cyan toner, yellow toner, and black toner were applied in this order. During transfer, the transfer current applied to the transfer corotron is 200 mA for magenta toner, 250 mA for cyan toner, and 300 mA for yellow toner.
In the case of black toner, the voltage was 350 mA.

The replenishment toner sent by the supply screw 16 in the toner conveyance cable 4 is supplied to the developing device 2 through the toner replenishment port 15.
2 and was supplied into the developing device.

When the developing device rotates and comes to a position facing the photosensitive drum 1, the replenishing toner is uniformly mixed with the developer within a very short time by the mixing/conveying screw 12, resulting in two-component development with a constant developer concentration. It became a drug. The developer is made into a constant amount by the developer regulating blade 14 on the developing sleeve 13, and is subjected to reversal development using the J/B development method at the opposing portion of the photosensitive drum 1 having a negatively charged electrostatic latent image. By this method, negatively charged toner was transferred onto the photosensitive drum.

Next, the toner image on the photosensitive drum 1 was transferred via the transfer charger 8 to an image support having a transparent coat layer, which had been previously conveyed from the paper cassette and electrostatically adsorbed onto the transfer drum 6 . The support was further passed through a hot roll fixing device IO to form the final full color copy.

FIG. 3 shows temperature-apparent viscosity curves of the toner and coating layer members used in the examples.

A relatively high-density high-quality paper was used as the image support, and the coating layer was prepared by dissolving 10 g of a polyester resin consisting of terephthalic acid, trimellitic acid, propoxyl bisphenol, and ethoxylated bisphenol in 100 g of methyl ethyl ketone. 14 bar coater was used to coat the above-mentioned high quality paper.

The obtained full-color copy had excellent reproducibility of color tone and character portions of the color original. The chromaticity diagram at that time is shown in FIG.

The cross coverage of yellow, magenta, and cyan monochrome images used for chromaticity measurement was 27%, 32%, and 25%, respectively.

At this time, the fixing roll used in the fixing device IO had a two-layer structure including an HTV silicone rubber layer with a thickness of 1 mm on a core metal, and a silicone resin layer with a thickness of 70 gm on the surface layer. A 3 mm HTV silicone rubber was used as the pressure roll.

Using the above-mentioned hot roll fixing device, using the image support having the above-mentioned transparent coat layer,
Although 0 sheets were repeatedly copied, no offset occurred on the heat fixing roll.

Styrene made of styrene, methyl methacrylate, and 2-ethylhexyl acrylate as a coating layer member.
Using acrylic copolymer, magenta colorant is c, r
A monochromatic magenta copying test was carried out in the same manner as in Example 1, except that 1223.5 parts of , Pigment Red, and 491.0 parts of C, R, and Solvent Red were used.

An image with excellent brightness and chroma and high gloss (cross) was obtained. By the way, the cross rate at this time was 30%.

In JJ Kumidan heat roll fixing device, place the fixing roll on the core metal 1
．． It has a two-layer structure: an LTV silicone rubber layer with a thickness of 5mm and a silicone resin layer with a thickness of 30μ on the surface layer. Example 1 except that the layer was thin
Copying was repeated in the same manner.

Even after 12,000 full-color copies were made, color copies with excellent saturation were obtained, with the image remaining the same as the initial image.

In the case of full-color copying, there are many four-color overlapping parts on the image, and this test shows whether the load on the fixing roll is much greater in terms of offset and durability than when copying in a single color. In this case, even after 12,000 sheets, the offset resistance of the fixing roller was almost unchanged from the initial state.

Comparative Side Full-color copying was performed using plain high-quality paper instead of the image support having the transparent coat layer of the present invention.

The chromaticity at that time is shown in FIG. It can be seen that although the hue is similar compared to Example 1, the saturation is clearly lower. Yellow, magenta, and cyan crosses were 15%, 18%, and 16%.

10-1 The binder resin for toner was replaced with a styrene-acrylic copolymer consisting of styrene-butyl acrylate-maleic acid-2-ethylhexyl acrylate, and the cyan colorant was replaced with c.
, r, and 6.0 parts by weight of Pigment Blue 15, and the yellow coloring agent was changed to c, r.

The test was conducted in the same manner as in Example 1, except that 2.3 parts by weight of Disperse Yellow 54 was used. An image with favorable brightness, excellent saturation, and a high cross color balance was obtained. The temperature-apparent viscosity curve of the toner used is shown in FIG.

Oketsu Shiko fixing roll is silicone rubber (HTV) - Teflon film coated (tetrafluoroethylene resin) - silicone rubber (RTV)
It has a three-layer structure with a layer thickness of 2. Omm, hardness 50 degrees,
A roll with a diameter of 60 mm is used as the pressure roll.
A two-layer structure of silicone rubber (HTV) and Teflon coat (tetrafluoroethylene resin) was used, with a layer thickness of 1.0 mm, a hardness of 60 degrees, and a roll diameter of 60+nmφ. The heating device was attached to both the pressure roll side and the fixing roll side.

Further, full-color copying was carried out in the same manner as in Example 1, except that the transparent coat layer member was changed from polyester resin to styrene-acrylic copolymer made of styrene-butyl methacrylate. A full-color image with higher gloss and better saturation than Comparative Example 1 was obtained. The temperature-apparent viscosity curve of the coating layer member is shown in FIG.

Even after printing 10,000 sheets in full color mode, there was no offset to the fixing roller, and a full color image with no fog and excellent color mixing was obtained.

The transparent coating layer member is made of epoxy resin, and the image support is made of 2
Full-color copying was carried out in the same manner as in Example 1 except that a polyethylene film having a thickness of 00H was used. OH
The P image had excellent yellow transparency.

Although more than 50,000 copies were repeatedly made in the yellow single color mode, no offset to the fixing roller was observed at all.

Noshidan 1 Full-color copying was performed in the same manner as in Example 1, except that the toner binder resin used in Example 4 was used as the transparent coating member. In the resulting image, the characters were noticeably thickened and blurred, and there was a lot of blurring, especially for type of 5 points or less, and the divisions between thin lines in the text were unclear.

When copying was repeated using this image support, after only 1,200 copies were made, there was a large amount of offset to the fixing roller, resulting in offset on the entire image.

The fixing roller was made of HTV silicone rubber with a ratio of 4.71, the pressure roller was made of 1.5mm LHV silicone rubber coated with fluorine latex, and the roll temperature was set at 170°C, and the other parts were as in Example 4. When full-color copying was performed repeatedly in the same manner as above, offset occurred after only 5,300 copies were made, making it impractical.

Further, the fixing roll was subject to thermal deterioration, and the roll material was peeling off from the core bar.

At a set temperature of around 130° C., at which the HTV silicone rubber is not subject to thermal deterioration, the fixed image was a dull full-color image with low gloss and poor fixation.

[Effects of the Invention] The present invention provides that the toner and coating layer member have an apparent melt viscosity of 1.
By specifying the temperature difference resulting in 0.06 poise within an appropriate range and further improving the fixing roll, color mixing and sharpness that can faithfully reproduce the original can be obtained, and there is no offset to the heated roller.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of a color electrophotographic apparatus having an OPC photosensitive drum, FIG. 2 shows a schematic diagram of the replenishment and development system of the apparatus shown in FIG. 1, and FIG. 3 shows the temperature of toner and coating layer members. -Appearance shows a viscosity curve, and Figure 4 shows a chromaticity diagram of a color original.

Claims (1)

[Claims] (1) In an image forming method in which a toner image is formed on a transparent coat layer provided on an image support, and the support having the toner image is subjected to hot roll fixing, [1] the appearance of the toner and coat layer members is The difference in temperature at which the melt viscosity becomes 10^5 poise is expressed by the following formula 3<T_2-T_1<40 [T_1: Temperature at which the toner becomes 10^5 poise T_2:
[2] The fixing roll has at least a rubber-like elastic layer and an offset prevention layer on the core metal, and the pressure roll has a rubber-like elastic layer on the core metal. An image forming method characterized by using a hot roll fixing device having a shaped elastic layer.