JP2966050B2 - Color toner for heat roll fixing - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing method applied to an image recording method such as electrophotography and electrostatic recording, and more particularly, to a color capable of fixing a translucent color image for OHP. Related to toner.

[Conventional technology]

Non-contact heat fixing method using an oven, light fixing method using a flash lamp, pressure fixing method using a pair of pressure rollers, contact heating method using a heat roller, etc. can be used as a method for fixing character image information formed on a material to be fixed. Are known.

Among them, the non-contact heating method has a problem that the heat source becomes high temperature, so that the apparatus becomes large and cannot be used for a small recording apparatus. Further, in the pressure fixing method, since a rigid roll is used, there is a problem that the weight increases. On the other hand, in the contact heating and pressurizing method using a heat roller, fixing is performed by passing a material to be fixed between a heat fixing roller and each pressure roller. In this method, the heat fixing roller and the unfixed image come into pressure contact with each other, so that the heat efficiency is extremely good and the fixing can be performed quickly. Also, the heat source does not need to be so hot, and the device can be downsized. However, in this method, since the melted toner on the surface of the heat fixing roller is in pressure contact, a part of the toner used for image recording adheres to the heat fixing roll and causes a so-called offset phenomenon that the toner adheres to the next recording material. . For this purpose, techniques for coating the surface of the heat-fixing roller with a material having releasability, and adding a polyalkylene having releasability to the toner are disclosed.

In addition, in order to obtain a color image by fixing various color toners in which color dyes and pigments are dispersed in a binder resin for fixing, it is necessary to perform sufficient color mixing. Suitable for fixing.

However, even if a copy obtained by using a known color toner and a fixing method is an image having a clear color tone when viewed as a reflected light image, it can be used as a translucent color for OHP (overhead projection). When used to create an image, there is a tendency that a transmitted light image tends to be a dark image unlike the hue of the original toner.

This is because when light passes through the fixing toner image on the translucent sheet, light scattering and reflection occur at the interface between the translucent sheet and the fixing toner, inside the fixing toner, and at the interface between the fixing toner and air. This is because the transmittance decreases.

As a method of obtaining a translucent color fixed image for OHP, JP-A-60-52861, a method of performing a treatment for smoothing the surface of a fixed image described in JP-A-61-252559 is mentioned. However, these processes are complicated and contravene the simplicity that is a feature of electrophotography. Rather, with one fixation
It is desirable that an OHP translucent fixed image be obtained. Also,
There is a method described in JP-A-62-75645, in which a resin having a refractive index smaller than that of a light-transmitting sheet and having a refractive index larger than that of air is used as a binder resin for fixing. Even if a resin is used, a sufficient translucent color image cannot be obtained by a normal heat roller fixing method,
In addition, the special fixing resin has low reliability such as easy offset, and the cost of the resin increases.

On the other hand, when an OHP translucent color image is to be obtained with an existing full-color copying machine, the fixing speed is reduced to almost half that of a normal paper to be fixed by the OHP mode, and the fixing amount is almost twice that of a normal heat. OHP by giving thermal energy
A translucent color image is obtained.

[Problems to be solved by the invention]

Although the OHP translucent color image can be obtained by lowering the fixing speed to about half that when the material to be fixed is paper, a gear and an electronic circuit for switching the conveying speed and the fixing speed in such a method. Is necessary.
The complexity and size of the device are inevitable.

The reason for lowering the fixing speed in order to obtain an OHP translucent color image is to apply sufficient thermal energy to the unfixed toner, melt it, and make the fixed image surface flat.
Conversely, if the unfixed image on the OHP transmissive sheet is fixed by the conventional method at the same fixing speed as when the material to be fixed is paper, flattening and color mixing are sufficiently performed. Instead, the transmitted image has a blackish color.

In order to fix an OHP translucent color image at the same fixing speed as when the material to be fixed is paper, for example, a method of reducing the fixing speed of the paper can be considered, but this will reduce the function of the apparatus itself. Is not preferred. In addition, this method is unfavorable because offset tends to occur when the paper is fixed.

It is known that an unfixed image that can be fixed with a small amount of heat energy can be obtained by using a sharp-melting binder resin, but when such a resin is used, offset is very likely to occur. Conversely, to obtain an unfixed image in which offset does not easily occur, it is known to use a resin having a high melt viscosity, or use a crosslinked resin or a non-linear polyester. However, since an image formed by such a resin has a high cohesive energy at the time of fixing, although offset is not likely to occur, the fixing property and the gloss decrease. Further, when fixing is performed on an OHP sheet, the fixing surface has large irregularities, and a clear translucent image cannot be obtained.

Another method of making offset less likely is to add a large amount of a polyalkylene or wax having releasability. However, if a large amount of the second component incompatible with such a binder resin is present, a fixed image Self-turbidity occurs, and the light transmittance also decreases, which is not preferable.

An object of the present invention is to fix a clear OHP translucent color image at the same fixing speed as when the material to be fixed is paper, and further, to fix without causing offset when the material to be fixed is paper. It is an object of the present invention to provide a heat roller fixing toner that can be used.

Another object of the present invention is to provide a toner which is suitable for full-color image recording with sufficient color mixture and gloss, and at the same time has good heat-resistant storage stability.

It is another object of the present invention to provide a toner capable of obtaining an OHP translucent color image even in a functional color copy by switching a developing unit.

[Means for solving the problem]

In order to solve the above problems, as a result of intensive research, it has been established with less heat energy and has excellent offset resistance,
In addition, it has been found that it is extremely important that the toner particles forming the unfixed image have a specific softening temperature and a specific molecular weight distribution in order to obtain a flat fixing surface.

The present invention is based on the above findings, and more specifically, a toner for developing an electrostatic latent image formed from at least a binder resin and an organic pigment, having a melt viscosity of 10
⁵ Poise softening temperature is 90 ~ 120 ℃, molecular weight,
A binder resin having a weight average molecular weight (Mw) of 1.5 × 10 ^{4 to} 5.0 × 10 ⁴ , a number average molecular weight (Mn) of 2 × 10 ³ to 1 × 10 ⁴ and a dispersion ratio (Mw / Mn) of 5 to 15 is used. Use a masterbatch pigment in which an organic pigment is previously dispersed in a resin having a softening temperature equal to or lower than the softening temperature of a binder resin, and apply 0.3 to 1.5 wt% of inorganic fine particle powder treated with a silicone resin on a toner surface. The technical means of adding is adopted.

(Operation)

As the binder resin, a thermoplastic resin such as a styrene resin, a polyester resin, and an epoxy resin is used.

As the styrene resin, a styrene homopolymer and a copolymer with another vinyl resin are provided. Examples of the monomer for forming the copolymer include aromatic vinyls such as P-chlorostyrene and vinyl toluene, non-aromatic vinyls such as ethylene, propylene, butylene and vinyl chloride, vinyl acetate and vinyl acid. Esters, acrylic acid, methacrylic acid, unsaturated monocarboxylic acids such as α-chloroacrylic acid, esters of the above unsaturated carboxylic acids, as ester groups, methyl, ethyl, propyl, n-butyl, t-butyl, octyl, Nonyl, phenyl, 2-hydroxyethyl, 2-ethylhexyl, dimethylaminoethyl, glycidyl, etc., vinyl ethers, vinyl ketones, N-vinyls such as N-vinyl cardzol, N-vinyl pyrosodone, and unsaturated acids such as maleic acid Polycarboxylic acid, ester compound of unsaturated polycarboxylic acid, unsaturated polycarboxylic acid And the like of the acid anhydride. A resin obtained by copolymerizing one or more of these with styrene can be used. In particular, a copolymer of one or more monomers selected from unsaturated monocarboxylic acid esters and styrene is preferably used.

As a polyester resin, as an alcohol component,
Ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propyne glycol, 1,
4-butanediol, neopentyl glycol, 1,4
Non-aromatic diols such as butenediol, aromatic diols such as polyoxyethylene (6,0) -2,2-bis (4-hydroxyphenyl) propane, 1,2,4-
Trihydric or higher polyalcohols such as butanetriol, rilbitol, and pentaerythritol are exemplified. Examples of the acid component include dicarboxylic acids such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and malonic acid; A polyester resin selected from these alcohols and acids and synthesized can be used.

Further, the toner of the present invention is known for the purpose of improving image quality, pulverizability, fluidity, mold releasability, etc. within a range that does not impair the OHP translucency, anti-offset property, and fixing property of the object of the present invention. It is possible to add a resin. That is, styrene
Butadiene copolymer, styrene-isoprene copolymer,
Styrene-based copolymers such as styrene-acrylonitrile-indene copolymer, polyvinyl chloride, polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyurethane, epoxy, polyvinyl butyral, rosin, modified rosin,
Terpene resins, phenolic resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, chlorinated paraffins, paraffin waxes, solid alcohols and the like can be used alone or in combination.

In the heat roller fixing color toner of the present invention, the softening temperature at which the melt viscosity by a flow tester becomes 1.0 × 10 ₅ poise needs to be 90 ° C. or more and 120 ° C. or less. The melt viscosity of the toner is an apparent viscosity of the toner as a whole including a binder resin, a colorant, and additives as necessary. When the softening temperature at which the melting temperature becomes 1.0 × 10 ⁵ poise is lower than 90 ° C., the offset resistance is insufficient.On the other hand, when the softening temperature is higher than 120 ° C., a large amount of heat energy is used for fixing. It is necessary and it is difficult to fix translucent images on OHP sheets at sufficient speed.

In the present invention, the melt viscosity is measured, for example, using a flow tester CFT-500 (manufactured by Shimadzu Corporation) under the following conditions. That is, about 1.0 g of a sample (toner) is weighed and pressurized by an attached molding machine. The melt viscosity of this sample is determined from the Hagen-Poiseuille equation in a flow tester measurement under the following conditions to obtain the melt viscosity used in the present invention.

<Measurement conditions> Heating rate: 3.0 (° C / min) Initial temperature: 70 (° C) Maximum temperature: 200 (° C) Sampling interval: 3 (° C) Preheating time: 300 (seconds) Load: 30 (kg) Die Diameter: 1.0 (mm) Die length: 10.0 (mm) Plunger bottom area: 1.0 (cm2) The logarithm logη of the measured melt viscosity η is converted to the temperature T (1 / ゜ K
When plotted with the reciprocal of the absolute temperature), a graph that is almost a straight line is obtained. In the present invention, this straight line has a viscosity η = 1.0
The temperature crossing × 10 ⁵ was used as the softening temperature.

In the color toner according to the present invention, the molecular weight of the binder resin is 1.5 × 10 ^{4 to} 5.0 × 1 (weight average molecular weight (Mw)).
0 ^4, a number average molecular weight ^{(Mn) 1.5 × 10 3 ~1.0} × 10 4 a and variance ratio (Mw / Mn) is necessary to use a 5 to 15. When the molecular weight (Mw) is smaller than 1.5 × 10 ⁴ , offset tends to occur. Conversely, when the molecular weight (Mw) is larger than 5.0 × 10 ⁴ , the fixability is poor. When the dispersion ratio is less than 5, the gloss of the image is large, but offset tends to occur. When the dispersion ratio is more than 15, the self-cohesive force of the toner increases, and the fixing surface is less likely to be flat.
There is a disadvantage that the light transmittance when fixed on the OHP sheet is reduced. The molecular weight of the resin can be determined by dissolving the resin in a solvent such as tetrahydrofuran and performing gel permeation chromatography (GPC). For the calibration curve, use polystyrene with a pre-determined molecular weight of the monodispersion ratio,
The molecular weight of the resin is determined as a value in terms of polystyrene.

The toner according to the present invention having the above-described thermal characteristics needs to include, as a colorant, a master batch pigment in which an organic pigment is previously dispersed in a resin having a softening temperature equal to or lower than the softening temperature of the binder resin. Dyes and pigments are known as colorants, but the dyes are compatible with the resin, and the transparency of the OHP image of the obtained toner is high. However, the dye has the drawbacks that it is susceptible to changes due to heat during the production of the toner, and that it is inferior in light resistance and bleeding property to the silicone rubber fixing roller. In addition, the pigment is not compatible with the resin and is only dispersed, but the usual dispersing method has a problem that the dispersibility is poor and the transparency of the OHP image is reduced. Therefore, as a method of uniformly dispersing the pigment in the toner, by using a master batch pigment in which the pigment is dispersed in a resin having a softening temperature equal to or lower than the softening temperature of the binder resin, the dispersibility of the pigment is extremely high. It was found that the transparency was good and the transparency of the obtained OHP image was as high as that when the dye was used. It is preferable to use a resin having high compatibility with the binder resin for the toner,
Is the softening temperature the same as the softening temperature of the binder resin?
It is desirable that the temperature is lower by about 20 ° C. If the softening temperature of the masterbatch resin is higher, sufficient dispersion cannot be obtained, the pigment is present as coarse particles in the binder, and the OHP transparency is low.

Known pigments can be used. For example, Cadmiumium Yellow, Hansa Yellow G, CI Pigment Yellow 17, Balifast Yellow 3120, Permanent Yellow NCG, Pyrazolone Orange, Benzidine Orange G, Cadmium Red, Brilliant Carmine 3B, Brilliant Carmine 6B, Fast Violet B, Quinacridone Magenta, Rhodacin 6G Lake, phthalocyanine blue, fast sky blue, malachite green lake and the like are used as needed. These pigments are preferably used in an amount of 0.5 to 10 parts by weight based on 100 parts by weight of the binder resin. As a method for producing a masterbatch pigment, the ratio of resin to pigment is preferably such that the pigment component in the masterbatch is 10 to 90 wt%,
This mixture can be produced by dispersing by applying a mechanical shear in a heat-melted state or in a state in which a solvent is added, returning the mixture to a solid state, and then pulverizing the mixture. In order to improve the dispersibility of the pigment, it is possible to add an appropriate dispersant.

In the heat roller fixing color toner according to the present invention, it is necessary that 0.3 to 1.5 wt% of inorganic fine particle powder treated with a silicone resin is added to the toner surface. It is known to add inorganic fine particle powder to the toner surface,
This is indispensable for improving the fluidity and heat-resistant storage stability of the toner. In addition, these inorganic fine particles are often hydrophobicized in order to prevent the chargeability of the toner from being lowered at high humidity.In particular, inorganic fine powder treated with silicone resin has sufficient storage stability with a smaller amount of addition. It has been found that there is an improvement effect. In order to increase the transparency of the OHP image, it is necessary to add these inorganic fine powders as little as possible.

However, in order to obtain a flat fixing surface with less heat energy, the binder resin of the toner has a low softening temperature. The storability of the toner is related to the glass transition temperature of the binder resin, and a resin having a low softening temperature also has a low glass transition, so that the fixability and the storability are contradictory.

Therefore, it is necessary to add an inorganic fine powder having a high storability improving effect with a smaller addition amount, particularly for OHP toner. As the silicone resin for inorganic fine powder treatment according to the present invention, a known silicone resin such as a dealcohol type or deoxime type of straight silicon can be used.

As described above, the transparency of the OHP image according to the present invention is greatly affected by the fixing method. The color toler according to the present invention is preferably fixed by a fixing roller having the following configuration.

That is, it is desirable that the heat fixing roller has a release resin surface layer provided on the elastic layer. The elastic layer of the heat fixing roller is provided outside a core metal such as aluminum having good thermal conductivity, and silicone rubber, fluorine rubber or the like which does not lose elasticity by heat is preferably used. The thickness of the elastic layer is preferably 0.5 mm or more. If the thickness of the elastic layer is too small, it has no meaning as the elastic layer, and it is necessary to provide the elastic layer with 0.5 mm or more. In addition, from the viewpoint of heat supply, the thickness is desirably 2 mm or less.

The release resin surface layer provided outside the elastic layer of the heat fixing roller is made of polytetrafluoroethylene (PT
FE) and fluororesins such as perfluoroalkoxy-titrafluoroethylene copolymer (PFA) are preferably used.

To fix an unfixed image on an OHP sheet or film and obtain a transparent image at a relatively high fixing speed, the nip width
It is necessary to set the hardness and the pressing force of the heating roller and the pressing roller so that the pressure is 3.0 mm or more and the pressing pressure is 3 kg / cm ² or more.

In the toner according to the present invention, even if an unfixed image is formed by using the toner within the above-described range, the heating roller of the fixing roller pair that is in contact with the unfixed toner is moved away from the fixing roller. When a translucent image is obtained using a heating roller that does not have an elastic layer below the conductive surface layer, a translucent image is obtained, but the transmittance is low and the projected image differs from the color tone originally possessed by color toner. Will be.
Further, when an unfixed image on paper is fixed at the same speed, offset is likely to occur.

The reason for this is not necessarily clear, but the present inventors presume as follows. That is, the elastic layer provided on the heating roller makes the contact between the heating roller and the unfixed toner and the material to be fixed dense, and more uniform heat supply is performed. The toner deformed by the heat and pressure between the two rollers in the fixing process exerts a cohesive force to minimize the surface energy. The toner close to the elastic body has a long relaxation time of the stress, re-aggregates after fixing, and the surface becomes uneven. Such a toner layer has good offset resistance, but a heating roller (hard roller) having no elastic layer cannot form a flat OHP translucent surface. To obtain a fixed image having a flat surface with a hard roller can be achieved by lowering the softening temperature of the toner, especially by reducing the molecular weight distribution. However, such a toner has low offset resistance and is not practical.

However, in a heating roller having an elastic layer, since the elastic layer also has a certain length of stress relaxation time, it is possible to prevent the re-aggregation of the toner deformed at the time of fixing, and to apply a flat surface to the toner having offset resistance. It is considered that the image can be fixed as a fixed image having the image.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples. Hereinafter, unless otherwise specified, parts are parts by weight.

(Example 1) Styrene-n-butyl acrylate copolymer (Sanyo Chemical Co., Ltd., Hymer SBM73F) 65 parts Styrene-2 ethylhexyl acrylate copolymer (Sekisui S-Lec P) 25 parts The molecular weight of the binder resin obtained by combining these is weight average molecular weight 3.2 × 10 ⁴ , number average molecular weight 8.1 × 10 ³ , dispersion ratio 4.0.

Masterbatch pigment 10 parts This is a mixture of styrene-n-butyl acrylate copolymer (Sanyo Kasei Hymer SBM100, softening temperature 93.5 ° C) 60 parts and organic pigment (CI Pigment Yellow 12) 40 parts with solvent and dispersant (ICI Hypermer PS3) A mixture obtained by mixing and dispersing together with 3 parts of the mixture, removing the solvent, and pulverizing to 5 μm or less.

Load control agent (Pondlon E-88 manufactured by Orient Chemical) 1 part The components of the above formulation were kneaded using a three-roll mill, cooled, and then pulverized with a hammer mill and a jet mill. 0.7 parts of colloidal silica (# 130 manufactured by Nippon Aerosil) coated with a silicone resin (SR2410 manufactured by Dow Corning Toray Silicone) was mixed with a Henschel mixer, and classified into a particle size of 5 to 15 μm by a zigzag classifier. Of yellow toner (toner A) was obtained.

This toner A was measured by the flow tester, and η
The softening temperature that resulted in = 105 poise was 104 ° C.

For 3.5 parts by weight of this yellow toner, Ni carrier 1
00 parts by weight were mixed to obtain a developer. This developer was applied to a color copying machine (Model 6800 manufactured by Fuji Xerox) to obtain a red unfixed image.

This unfixed image was fixed by the following hot roll fixing machine. The heating roller has a fluoro rubber layer 1.0 mm on a 29 mm diameter aluminum cored bar, and a 20 μm perfluoroalkoxy-tetrafluoroethylene copolymer (PFA) on the surface.
Those having a thickness of m were used. Outer diameter as pressure roller
Using a 25 mm iron core bar having a 3.5 mm thick silicon rubber sheet layer, a fixing device with a variable fixing speed using a 900 W halogen lamp as a heat source was assembled. The nip width of this fuser is
4 mm and a pressure contact force of 4.0 kg / cm ² .

Using this fixing machine, heat roller surface temperature to 190 ℃
Transport speed 63mm / sec, 100mm / sec, 133mm / s
Established at ec. When the material to be fixed was paper (64 g paper), there was no offset at any speed, a glossy image was obtained, and the fixing rate by tape peeling was 90% or more.

The material to be fixed was changed to an OHP sheet (manufactured by Gakken), and the fixing speed was similarly changed to perform fixing. At any speed, fixing was possible without offset. OHP projection images are 63, 100, 133 mm / se
All were clear at a fixing speed of c.

The above-mentioned heating roller fixing machine was incorporated into a commercially available copier (Leo Dry 4121 manufactured by Toshiba), and the size of 64 g paper A4 size 1
A 10,000-sheet running test was performed. A good image was obtained even after the running test, and there was no change in the fixing property and the translucency of the image on the OHP sheet as compared with the initial level. Also, almost no stain was observed on the web provided as a knurling means for the heating roller.

In addition, 5 g of this toner was placed in an open cup, exposed after being exposed to a constant temperature bath controlled at 55 ° C. for 24 hours, and then taken out.The heat resistance storage stability of the toner was examined. Was.

(Example 2) Polyester resin (KTR1110 manufactured by Kao) 85 parts Polywax (BESQURE195 manufactured by BARECO) 5 parts Master batch pigment 10 parts 4 parts CI pigment red 122, 6 parts styrene acrylic resin (SBM100 manufactured by Sanyo Chemicals), and dispersion 0.3 parts of material (Hypermer P53 manufactured by ICI) previously dispersed, mixed and pulverized Charge control agent (E-84 manufactured by Orient Chemical) 1 part Magenta toner in the same manner as in Example 1 except that the components of the above formulation were used. And a developer.

The softening temperature (η = 10 ⁵ poise) of this toner was 100 ° C. The molecular weight of the binder resin is the weight average molecular weight.
1.5 × 10 ⁴ , number average molecular weight 2.5 × 10 ³ , dispersion ratio was 6. Using this developer, an unfixed image was formed in the same manner as in Example 1, and a fixing test was performed on paper and an OHP sheet. Was. At any of the fixing speeds, there was no offset and a clear translucent image could be fixed on the OHP sheet.

Furthermore, even after a 10,000-sheet running test with a copier,
The same image and fixability as in the initial stage were obtained, and almost no stain on the web was observed.

(Example 3) Styrene-metal methacrylate-n-butyl methacrylate copolymer 10 parts Styrene-acrylic resin (FB resin manufactured by Mitsubishi Rayon) 75 parts Polypropylene (Viscol 660P manufactured by Sanyo Chemical) 4 parts Master batch pigment 10 parts CI as a pigment Pigment Blue 15-3 except that Pigment Blue 15-3 was used. A charge control material (Orient Chemical E-88) 1 part A blue toner and a developer were obtained in the same manner as in Example 1 except that the above-mentioned components were used. Was. The softening temperature of this blue toner was 110 ° C. The molecular weight distribution of the binder resin is such that the weight average molecular weight is 4.0 × 10 ⁴ and the number average molecular weight is 4.
The dispersion ratio was 9 × 10 ³ .

An unfixed image was formed using this developer in the same manner as in Example 1, and a fixing test was performed on paper and an OHP sheet. As a result, there is no offset at any fixing speed and OH
A clear translucent image could be fixed on the P sheet. Also,
The heat resistance storage stability of this toner with an open cup was also sufficient.

(Comparative Example 1) Styrene-acrylic resin (Hymer SBM-100 manufactured by Sanyo Chemical Industries) 90 instead of 90 parts of styrene-acrylic resin of Example 1
A yellow toner was obtained according to the same formulation as in Example 1 except that the parts were used. The softening temperature of this toner is 93.5 ° C., the molecular weight is 1.5 × 10 ^{4 for} weight average molecular weight, 5 × 10 ^{3 for} number average molecular weight,
The dispersion ratio was 3. An unfixed image was formed using this toner, and the fixing was evaluated using the same fixing machine as in Example 1. As a result, offset occurred in both cases where paper and the OHP sheet were used as the material to be fixed. Also, OHP
The projected image was also a dark image due to the unevenness of the fixed image surface.

(Comparative Example 2) Instead of 90 parts of the binder resin of Example 1, styrene-
A yellow toner was obtained according to the same formulation as in Example 1 except that 90 parts of an acrylic resin (Emarek P manufactured by Sekisui) was used. This toner had a softening temperature of 107 ° C., a molecular weight of 1.2 × 10 ⁵ , a number average molecular weight of 5.7 × 10 ³ and a dispersion ratio of 20. An unfixed image was formed using this toner, and the same fixing evaluation as in Example 1 was performed. As a result, a translucent OHP image was not obtained at a speed of 100 mm / sec or more. But,
No offset was observed.

(Comparative Example 3) Fixing evaluation was performed using the same fixing machine as in Example 1, except that the yellow toner of Example 1 was used and a conventional roller having no rubber elastic layer was used as a heating roller. As a result, when the material to be fixed was paper, an offset was produced, and when the material was OHP, no offset was produced, but an image having irregularities on the surface was obtained, and the projected image of the OHP was not clear.

Comparative Example 4 In the magenta toner of Example 2, polystyrene (Picola Stick D-12) was used as the resin for the master batch.
A toner was prepared and evaluated using the same formulation and method as in Example 2 except that 5) was used. As a result, when fixed on paper, there was no change in color tone, but in the case of OHP images,
The projected image became dark. When the pigment in the toner particles was observed by an electron microscope using an ultra-thin section method, the pigment was insufficiently dispersed and aggregates were observed.

Comparative Example 5 A toner was prepared in the same manner as in Example 3, except that 1 part of hydrophobic silica (Nippon Aerosil R972) was used as the external additive on the toner surface in the cyan toner of Example 3. . Although the image characteristics of the obtained toner were good, caking occurred in the accelerated heat storage stability test (55 ° C. × 24 hours).

〔The invention's effect〕

The heat roller fixing color toner of the present invention has the configuration and operation as described above, and of course, it is possible to fix a glossy color image with sufficient color mixture without offset,
There is an effect that a clear OHP translucent color image can be obtained over a wide speed.

Claims (1)

(57) [Claims] An electrostatic latent image formed on at least a binder resin and an organic pigment in a color toner for developing an electrostatic latent image formed on a photoconductive conductor and fixing the electrostatic latent image by heat roller fixing. The toner for development, which has a melt viscosity of 10 ⁵ poise by a flow tester, has a softening temperature of 90 to 120 ° C., a molecular weight of 1.5 × 10 ^{4 to} 5 × 10 ⁴ , and a number average molecular weight (Mw) of 1.5 × 10 ^{4 to} 5 × 10 ⁴ . Molecular weight (Mn) 2 × 10 ³
A masterbatch in which an organic pigment is previously dispersed in a resin having a softening temperature equal to or lower than a softening temperature of a binder resin using a binder resin having a dispersion ratio (Mw / Mn) of 1 to 10 ⁴ and a dispersion ratio (Mw / Mn) of 5 to 15. 0.3-1.5 wt.% Of inorganic fine particles containing pigment and treated with silicone resin on the toner surface
A color toner for heat roll fixing, characterized by being added.