JPH09171265A - Electrophotographic transfer film and color image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a color image excellent in coloring property of a halftone image part of a projected image by using an electrophotographic copying machine. SOLUTION: This electrophotographic transfer film cosists of a transparent support 11 and an image receiving layer 12 comprising a polymer which can form an image by thermal fixing of a toner comprising a coloring material and a binder resin. The binder resin of the toner to be fixed has such property that the initial temp. of flowing is 75 to 90 deg.C. The initial temp. of flowing of the polymer in the image receiving layer 12 begins to flow is higher by 0 to 10 deg.C than the initial temp. of flowing of the toner. A color image is formed on the electrophotographic transfer film by supporting the toner at <=40 deg. inclination angle t from the image receiving layer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent electrophotographic transfer film capable of forming a color image using an indirect dry electrophotographic copying machine for plain paper, a full-color electrophotographic copying machine or various printers, Especially OHP
The present invention relates to a transfer film for electrophotography that can be used in (overhead projector), and a color image forming method for forming a color image on the transfer film for electrophotography.

[0002]

2. Description of the Related Art An indirect dry electrophotographic copying machine for plain paper is used, and a transfer film for electrophotography (hereinafter also referred to as a transparent film) is used in place of the plain paper, and a toner image is formed on this film. To form a projected image (transmissive image) with an OHP (overhead projector)
This method is widely used as a method for easily obtaining a projected image. In particular, recently, with the spread of indirect dry full-color electrophotographic copying machines and various printers, a method of forming a color image on a transparent film and forming a projected image by OHP has become popular. For this reason, a transfer film for electrophotography capable of forming a projected image having excellent coloring properties has been demanded.

However, the conventionally used electrophotographic transfer film for indirect dry electrophotographic copying machines of a single color (for black and white) is considerably improved in film transportability (running performance) and toner fixability. However, there are still many problems in forming a color image. That is, when a color image is formed on the electrophotographic transfer film using an indirect dry full-color electrophotographic copying machine or various printers, the projected image obtained by the OHP does not have sufficient color development, particularly in the halftone portion. A satisfactory color image cannot be obtained and the image becomes cloudy. This is because the toner image (toner particles) formed on the transparent film causes unevenness on the surface of the transparent film.
This is development in which the projection image is turbid because the P projection light is scattered. In particular, the degree of turbidity of the image increases because the unevenness increases in the halftone portion. Therefore, it is necessary to reduce such irregularities.

Japanese Unexamined Patent Publication No. 2-263642 discloses a film having a resin layer formed of a resin having a large storage elastic modulus at the fixing temperature of toner. The toner used here has a high softening point (105 ° C.),
The resin of the resin layer also has a high softening point, and the softening point is considerably higher (116 ° C.) than the softening point of the toner. For this reason, it is difficult to immediately enter the layer after the toner is melted, the unevenness in the halftone portion and the like becomes large, and the degree of turbidity of the image also increases.

In JP-A-63-92965, a transparent resin layer having a softening point of 50 to 100 μm lower than the softening point of the toner (softening point 60 to 80) is provided on the support, in the opposite manner to the above.
C.), a toner image is formed on this transparent resin layer, and then the toner image is embedded in the layer. In Japanese Patent Laid-Open No. 4-212168, a coating layer of a resin having a flow starting temperature lower than that of the toner (flow starting temperature is 68 ° C. in the embodiment) is provided by the same idea, and the image is made glossy to give a projected image color. An electrophotographic copy sheet having improved reproducibility has been proposed. The method described in the above publication uses a resin having a lower softening point or a lower flow start temperature (outflow start temperature) than the toner binder resin for the image receiving layer (transparent resin layer), so that the toner is hardly melted, The toner is intended to be embedded in the image receiving layer so as to reduce the unevenness on the image receiving layer after image formation. in this way,
When pressed and heated by the fixing roll, the image receiving layer softens earlier than the toner, and the offset phenomenon in which the image receiving layer adheres to the fixing roll and moves easily occurs. That is, the fixed image causes fine ripples like a shell pattern, turbidity occurs in the projected image, or the image receiving layer moves to the fixing roll at the time of fixing, the image disappears, and the image receiving layer adheres to the fixing roll. As a result, troubles such as winding of the transparent film having the image receiving layer around the fixing roll occur (this phenomenon is hereinafter referred to as an offset phenomenon). Further, based on the same idea as described above, JP-A-5-88400 also discloses a transparent resin which is compatible with the binder resin of the toner at the fixing temperature of the toner and has an apparent melt viscosity lower than that of the binder resin of the toner. A transfer film for electrophotography provided with a resin layer is disclosed.

[0006]

As described above, in the method described in JP-A-4-212168, etc., the polymer of the image-receiving layer has a lower flow starting temperature or softening temperature than the toner, and therefore melts. As described above, the resin softened by the heating fixing roll is easily transferred to the fixing roll to cause an offset as described above. Further, the above-mentioned JP-A-2-263
If the softening point of the polymer of the image receiving layer described in Japanese Patent No. 642 is simply set higher than the softening point of the toner, the molten toner cannot easily penetrate into the image receiving layer. Therefore, as a result of repeated studies by the present inventor, a toner that is relatively easy to melt is used, and the polymer of the image receiving layer has a particularly small inclination angle (contact angle) with the toner (good compatibility) and is more fluid than the toner. By using a polymer whose starting temperature is slightly higher or the same as that of the toner, it is set to soften the image receiving layer so that the toner easily penetrates into the image receiving layer while advancing the melting of the toner. It has become clear that it becomes possible to reduce the surface irregularities, and it is possible to obtain an image with excellent characteristics in which both the coloring property of the halftone image portion of the projected image and the offset phenomenon are improved.

Therefore, the present invention provides an electrophotographic transfer film capable of forming a color image excellent in color development of a halftone image portion of a projected image by using an electrophotographic copying machine. To aim. Further, the present invention, by using an electrophotographic copying machine, a color image excellent in color developability of a halftone image portion of a projected image on a transfer film for electrophotography,
An object of the present invention is to provide a color image forming method that can be formed without causing an offset.

[0008]

The above object is to provide an image receiving layer made of a polymer capable of forming an image on at least one surface of a transparent support by heating and fixing a toner made of a coloring material and a binder resin. The electrophotographic transfer film, wherein the flow starting temperature of the binder resin of the toner to be fixed is 75 to 90 ° C.,
An electron which is characterized in that the flow starting temperature of the polymer of the image receiving layer is higher than the flow starting temperature of the binder resin of the toner to be fixed by 0 to 10 ° C., and the inclination angle of the toner with the image receiving layer is 40 degrees or less. This can be achieved by a photographic transfer film.

The preferred embodiments of the electrophotographic transfer film of the present invention are as follows. 1) The flow starting temperature (outflow starting temperature) of the polymer of the image receiving layer is 80 to 95 ° C. 2) The difference between the outflow starting temperature of the polymer of the image receiving layer and the outflow starting temperature of the binder resin of the toner is 0.5 to 1
The temperature is 0 ° C (preferably 0.5 to 7 ° C). 3) The heat fixing temperature is 130 to 160 ° C.

4) Repeating dibasic acid component in which the polymer of the image-receiving layer contains at least one dicarboxylic acid unit selected from the group consisting of terephthalic acid units and 2,6-naphthalenedicarboxylic acid units, and sulfobenzenedicarboxylic acid units. The polyester comprises a unit and a repeating unit of a dihydric alcohol component including an ethylene glycol unit, a triethylene glycol unit, and an ethylene oxide adduct unit of bisphenol A. 5) In the above 4), the repeating unit of the dibasic acid component of the polyester is 60 to 95 mol% of at least one dicarboxylic acid unit selected from the group consisting of a terephthalic acid unit and a 2,6-naphthalenedicarboxylic acid unit, and Containing 5 to 17 mol% of sulfobenzenedicarboxylic acid units,
The repeating unit of the dihydric alcohol component contains 10 to 60 mol% of ethylene glycol units, 30 to 90 mol% of triethylene glycol units, and 5 to 40 mol% of ethylene oxide adduct units of bisphenol A. 6) In 4) above, the repeating unit of the dibasic acid component of the polyester comprises 60 to 95 mol% of terephthalic acid units, 0 to 35 mol% of isophthalic acid units, and 5 to 17 mol% of sulfobenzenedicarboxylic acid units. 7) In the above 4), the repeating unit of the dibasic acid component of the polyester is an isophthalic acid unit of 0 to 35 mol%, 2,
It consists of 60 to 95 mol% of 6-naphthalenedicarboxylic acid units and 5 to 17 mol% of sulfobenzenedicarboxylic acid units. 8) In the above 4), the repeating unit of the dibasic acid component of the polyester is 0 to 90 mol% of terephthalic acid unit,
Isophthalic acid unit 0 to 35 mol%, 2,6-naphthalenedicarboxylic acid unit 10 to 90 mol% and 5 to 17 mol%
Of sulfobenzenedicarboxylic acid units. 9) The number average molecular weight of polyester is 1500 to 500
It is in the range of 0. 10) The weight average molecular weight of polyester is 2500 to 15
000 range. 11) The (weight average molecular weight / number average molecular weight) of the polyester is in the range of 1.2 to 3.0.

12) The image receiving layer is 1 × 10 ⁹ to 1 × 10 ¹²
It has a surface electric resistance at 25 ° C. and 65% RH in the range of Ω. 13) The image receiving layer further contains a surfactant and a matting agent. 14) The layer thickness of the image receiving layer is in the range of 1 to 8 μm (preferably 1 to 4 μm). 15) The transparent support is made of polyethylene terephthalate.

Further, the above objects are as follows (1) to (3):
Step: (1) a step of imagewise exposing the surface of the photoreceptor to form a latent image, (2) the latent image and the flow starting temperature of the latent image being 75 to 9
A step of developing with one kind of two or more kinds of toners for forming a color image composed of a binder resin at 0 ° C. to form an image on the surface of the photoreceptor, and (3) the image on a transparent support. Of the transfer film for electrophotography, which comprises a polymer having a flow starting temperature of 0 to 10 ° C. higher than the flow starting temperature of the binder resin of the toner and an inclination angle with the toner of 40 ° or less. After the color image is transferred onto the electrophotographic transfer film by repeating the step of transferring to the image receiving layer for the number of kinds of the toner, the transfer image of the toner is heated to the fixing temperature of the toner. A color image forming method comprising forming a color image on the electrophotographic transfer film by pressing with a fixing device (eg, heat roll).

The preferred embodiments of the color image forming method of the present invention are as follows. 1) The flow starting temperature (outflow starting temperature) of the polymer of the image receiving layer is 80 to 95 ° C. 2) The difference between the outflow starting temperature of the polymer of the image receiving layer and the outflow starting temperature of the binder resin of the toner is 0.5 to 1
0 ° C. 3) The heat fixing temperature is 130 to 160 ° C.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The electrophotographic transfer film of the present invention basically has a constitution in which an image receiving layer is formed on one surface or both surfaces of a transparent support. 1 and 2 are cross-sectional views schematically showing the basic structure of the electrophotographic transfer film of the present invention. FIG. 3 is a cross-sectional view schematically showing the structure in which a conductive undercoat layer is provided between the transparent support and the image receiving layer.

FIG. 1 shows an electrophotographic transfer film having an image receiving layer 12 formed on one surface of a transparent support 11. A conductive undercoat layer may be provided between the transparent support and the image receiving layer. Also, on the opposite side of the image receiving layer, slipperiness,
You may provide a back layer for giving electroconductivity and improving a film running property. FIG. 2 shows an electrophotographic transfer film having image-receiving layers 22a and 22b formed on both surfaces of the transparent support 21. In FIG. 3, conductive undercoat layers 33a and 33a are formed on both surfaces of the transparent support 31.
b, an electrophotographic transfer film having image receiving layers 32a and 32b formed thereon is shown.

The transparent supports 11, 21 and 31 can be made of any material as long as it is transparent and has the property of withstanding radiant heat when used as an OHP. The materials include polyesters such as polyethylene phthalate; cellulose esters such as nitrocellulose, cellulose acetate, cellulose acetate butyrate,
Furthermore, polysulfone, polyphenylene oxide, polyimide, polycarbonate, polyamide, etc. can be mentioned. The heat resistant temperature of the film obtained from these materials is preferably 100 ° C. or higher. Among these, a polyethylene phthalate film is preferable because it has excellent heat resistance and transparency. The thickness of the film is
There is no particular limitation, but a particle size of 50 to 200 μm is preferable because it is easy to handle. Films with heat resistant temperature less than 100 ° C
When the toner is heated and fixed, the toner tends to be deformed, so that the plastic film is likely to wavy. Further, the film preferably has such a thickness that wrinkles hardly occur when it is softened by heating during fixing. Therefore, the thickness is preferably 50 μm or more, more preferably 75 μm or more. The upper limit of the film thickness is preferably 200 μm or less in consideration of the decrease in light transmittance, and further 150 μm.
m or less is preferable. Therefore, the thickness of the heat-resistant plastic film is preferably 50 to 200 μm, and more preferably 75 to 150 μm.

The image receiving layers 12, 22a, 22b, 32a and 32b are higher than the flow starting temperature of the binder resin of the toner to be fixed by 0 to 10 ° C., and the inclination angle of the toner with the image receiving layer is 40 degrees or less. Formed from a polymer. Further, as the polymer of the image receiving layer, the outflow starting temperature is 8
Those in the range of 0 to 95 ° C are preferable. The layer thickness is
1 to 8 μm is preferable, and 1 to 4 μm is particularly preferable. Examples of the polymer of the image receiving layer include polyester resin, polyether resin, acrylic resin, epoxy resin, urethane resin, amino resin and phenol resin. Water dispersible polymers are preferred. When the image receiving layer is used as a color toner, it is necessary to transfer and fix four color toners, and such a polymer of the image receiving layer preferably has high cohesive energy. Examples of such a polymer include at least one dicarboxylic acid unit selected from the group consisting of a terephthalic acid unit and a 2,6-naphthalenedicarboxylic acid unit, and a repeating unit of a dibasic acid component containing a sulfobenzenedicarboxylic acid unit, and ethylene. A polyester comprising a repeating unit of a dihydric alcohol component including a glycol unit, a triethylene glycol unit and an ethylene oxide adduct unit of bisphenol A is preferable.

The polymer of the present invention (preferably the above polyester) having a temperature of 0 to 10 ° C. higher than the flow starting temperature of the binder resin of the toner and having an inclination angle of 40 degrees or less with the image receiving layer of the toner has a toner fixing temperature ( (Around 150 ℃)
Since it softens moderately with, the toner softened earlier than that,
Since it is easily embedded in the image receiving layer having a low inclination angle with the toner (excellent in compatibility), a fixed image having almost no unevenness can be obtained. Further, in the polymer of the image receiving layer of the present invention, since the toner and the image receiving layer are compatible with each other at the interface, the occurrence of the interface between the toner and the image receiving layer is almost eliminated, and thus the refraction of light from the overhead projector is almost eliminated. It is possible to obtain an image having excellent color development without turbidity as a projected image.

In the polyester, the repeating units of the dibasic acid component are terephthalic acid units and 2,6-
60 to 95 mol% of at least one dicarboxylic acid unit selected from the group consisting of naphthalene dicarboxylic acid units,
And sulfobenzenedicarboxylic acid unit 5 to 17 mol%
The repeating unit of the dihydric alcohol component comprises 10 to 60 mol% of ethylene glycol units, 30 to 90 mol% of triethylene glycol units and 5 to 40 mol% of ethylene oxide adduct units of bisphenol A.
It is preferable to include. The polyester having such a composition is a water-dispersible polymer. What is a water-dispersible polymer?
It is a polymer that itself can be easily dispersed in water and maintain its dispersed state for a long period of time.

The amount of the sulfobenzenedicarboxylic acid or its alkyl or hydroxyalkyl ester used is preferably 5 to 17 mol% of the total dibasic acid component, and more preferably 6 to 15 mol%.

In the above-mentioned sulfoaryldicarboxylic acid or its alkyl or hydroxyalkyl ester, hydroxyalkyl is hydroxyethyl group,
Examples thereof include hydroxypropyl group, hydroxyisopropyl group and hydroxybutyl group, and examples of alkyl include methyl group, ethyl group, isopropyl group, propyl group and butyl group. Particularly, a hydroxyethyl group is preferred. The sulfo group is sodium,
It is preferably a potassium or lithium salt, particularly preferably a sodium salt. The sulfobenzenedicarboxylic acid or its alkyl or hydroxyalkyl ester is preferably isophthalic acid, terephthalic acid or phthalic acid having a metal base of sulfonic acid, or a lower alkyl ester or a lower hydroxyalkyl ester of these acids, particularly preferably Isophthalic acid or a lower alkyl or lower hydroxyalkyl ester thereof having a metal base of sulfonic acid, and further isophthalic acid methyl ester or hydroxyethyl ester having a metal base of sulfonic acid are preferable.

The ethylene oxide adduct of bisphenol A preferably has an ethylene oxide addition number of 1 to 5 mol (preferably 1 or 2 mol).

The number average molecular weight of the above polyester is 15
The range of 00 to 5000 is preferable. The weight average molecular weight of the polyester is preferably in the range of 2500 to 15000. The (weight average molecular weight / number average molecular weight) of the polyester is preferably in the range of 1.2 to 3.0.

In the present invention, as described above, a polymer having a flow starting temperature in the range of 80 to 95 ° C. is used. The flow start temperature is defined as follows.
For example, a high-performance flow tester as shown in FIG. 4 can be used to obtain a plastic curve of the polymer, and the outflow start temperature (that is, the flow start temperature) can be determined from this curve. That is, an appropriate amount of the polymer of the sample is put in the position of the sample filling section 44 of the heating cylinder section 43 at the center of the elevation type flow tester of FIG. When the temperature of the heating cylinder portion 43 is increased at a temperature rising rate (eg, 1, 3 or 6 ° C./minute), the temperature (time) and the drop of the blanker 41 as shown in FIG. A relationship diagram with quantity is drawn. In FIG. 4, 41 is a blanker, 42 is a mercury thermometer, 45 is a pressure screw, and 47 is a die.

In FIG. 5, AB is the softening region of the polymer, T _s is the softening temperature, BC is the stopping region, T _fb is the outflow onset temperature (ie flow onset temperature), and CDE is It is a flow region. The flow start temperature is
After a slight rise of the blanker due to the thermal expansion of the sample, it is the temperature at which the blanker clearly starts to fall again, which can be read by the dial gauge at a 1/100 mm drop. Regarding the measurement of the flow initiation temperature, the polymer material test method (Polymer Engineering Course 14, 36
4 to 369, edited by The Polymer Society of Japan, Jijijinshokan Co., Ltd., 1938). In this polymeric material testing method, the term "flow start temperature" is "outflow start temperature".
It is described.

The inclination angle of the toner with respect to the image receiving layer (toner inclination angle) is measured as follows. 1) Disk molding of toner or toner binder A tablet frame having a diameter of 13 m as shown in FIG. 7 of a tablet molding machine (Hand Press SSP-10 type, Shimadzu Corporation).
m, height 3.3 mm, the non-magnetic two-component toner is filled with the toner itself, and the magnetic one-component toner is filled with the binder resin, and a hand press applies a load of 1 ton for 1 minute. In addition, a disc as shown in FIG. 8 was molded. The above disc has a diameter of 13 mm and a thickness of 1.2.
mm, and weighed 183 mg.

2) Melting and Solidification of the Disc As shown in FIG. 9, the disc 103 is placed on the electrophotographic transfer film 102, and the toner disc is heated and melted for 90 seconds (for electrophotography). When the transferred film is passed through the fixing device, the temperature of the film is about 20 ° C. lower than the temperature of the fixing device.
℃). This laminate has a thickness of 1 mm and 420 mm x 2
It was placed on an aluminum plate 101 having a size of 97 mm for 1 minute and rapidly solidified.

3) Measurement of toner inclination angle Using a contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd.),
The angle (contact angle) formed by the cut line drawn on the toner and the film surface at the contact point with the solidified electrophotographic transfer film of the toner (disc) was measured on each of the left and right sides, and the average value was taken as the melted toner inclination angle. .

The image receiving layer may contain a matting agent. Since the addition of the matting agent can improve the slipperiness, it also has a good effect on abrasion resistance and scratch resistance. As the material used for the flat matting agent, fluororesin, low molecular weight polyolefin organic polymer (eg, polyethylene matting agent, paraffinic or microcrystalline wax emulsion), substantially spherical matting agent Examples of the material to be used include bead-shaped plastic powder (material example, cross-linked PMMA, polycarbonate, polyethylene terephthalate, polyethylene or polystyrene), and inorganic fine particles (eg, SiO 2).
₂ , Al ₂ O ₃ , talc or kaolin). The content of the matting agent is preferably 0.1 to 10% by weight based on the polymer.

The image receiving layer preferably has a surface electric resistance in the range of 1 × 10 ⁹ to 1 × 10 ¹³ Ω (under the conditions of 25 and 65% RH). If it is less than 1 × 10 ⁹ Ω, the toner amount when the toner is transferred to the image receiving layer of the electrophotographic transfer film is not sufficient and the density of the obtained toner image is low, while 1 × 10 ¹³ Ω is set. If it exceeds the above range, an excessive charge is generated during transfer, the toner is not transferred sufficiently, and the image density becomes low. The electrophotographic transfer film is charged with static electricity during the handling of the electrophotographic transfer film, and is liable to be adhered to the film. In addition, misfeed, double feed, discharge mark, toner transfer drop, and the like are liable to occur during copying.

The image receiving layer may contain a surfactant for the purpose of adjusting the surface electrical resistance of the image receiving layer.
Examples of the surfactant include alkylbenzene imidazole sulfonate, naphthalene sulfonate, carboxylate sulfonate, phosphate, heterocyclic amines, ammonium salts, phosphonium salts and betaine amphoteric salts, or ZnO, SnO ₂ , Al ₂ O ₃ ,
Mention may be made of metal oxides such as In ₂ O ₃ , MgO, BaO and MoO ₃ .

For the image-receiving layer, if desired, known materials such as a colorant, an ultraviolet absorber, a cross-linking agent and an antioxidant may be used as long as they do not impair the characteristics of the electrophotographic transfer film of the present invention. it can.

The image-receiving layer is formed, for example, by dispersing or dissolving the polymer, matting agent, antistatic agent, etc. in water or an organic solvent, coating the resulting coating solution on the transparent support, and heating and drying. Can be carried out. The coating can be performed by a known coating method such as an air doctor coater, a bread coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, and a bar coater.

The transfer film for electrophotography described above has a structure in which an image receiving layer is provided on a transparent support.
When the desired surface electric resistance cannot be obtained, an antistatic agent may be used, or a conductive undercoat layer may be provided between the transparent support and the image receiving layer. As a method for obtaining a desired surface electric resistance, it is preferable to adopt the installation of a conductive undercoat layer. The conductive undercoat layer is a layer in which conductive metal oxide particles are dispersed in a binder. Materials for the conductive metal oxide particles include ZnO, TiO, SnO ₂ , Al ₂ O ₃ and I.
Mention may be made of n ₂ O ₃ , SiO ₂ , MgO, BaO and MoO ₃ . These may be used alone or as a composite oxide of these. Further, it is preferable that the metal oxide further contains a different element, for example, ZnO is Al, In, or the like, and TiO is N.
b, Ta and the like, SnO ₂ is preferably one containing Sb, Nb, a halogen element or the like (doping).
Among these, SnO ₂ doped with Sb is particularly preferable. The particle size of the conductive metal oxide particles is 0.2.
μm or less is preferred.

As the material for the binder of the conductive undercoat layer, polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyhydroxyethyl acrylate, polyvinylpyrrolidone, water-soluble polyester, water-soluble polyurethane, water-soluble nylon, water-soluble epoxy. Water-soluble polymers such as resins, gelatin, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and their derivatives; water-dispersible resins such as water-dispersed acrylic resins and water-dispersed polyesters; acrylic resin emulsions, polyvinyl acetate emulsions, SBR (styrene -Butadiene / rubber) emulsions such as emulsions; organic solvent-soluble resins such as acrylic resins and polyester resins. Water-soluble polymers, water-dispersible resins and emulsions are preferred. It is preferable to add the above-mentioned nonionic surfactant to these polymers. Further, a cross-linking agent or other surfactant may be added. The conductive undercoat layer can be formed in the same manner as in the image receiving layer.

The electrophotographic transfer film thus obtained can be heat-fixed in the next step using a color toner to form an image. (1) a step of imagewise exposing the surface of the photoconductor to form a latent image, (2) coloring the latent image with a coloring material at a flow starting temperature of 75 to 9
A step of developing with one kind of two or more kinds of toners for forming a color image composed of a binder resin at 0 ° C. to form an image on the surface of the photoreceptor, and (3) the image on a transparent support. Of the transfer film for electrophotography, which comprises a polymer having a flow starting temperature of 0 to 10 ° C. higher than the flow starting temperature of the binder resin of the toner and an inclination angle with the toner of 40 ° or less. After the color image is transferred onto the electrophotographic transfer film by repeating the step of transferring to the image receiving layer for the number of kinds of the toner, the transfer image of the toner is heated to the fixing temperature of the toner. A color image is formed on the electrophotographic transfer film by pressing with a fixing device (heat roll or the like). In the present invention, as described above, as the polymer of the image receiving layer, the flow starting temperature is higher than the flow starting temperature 0 to 10 ° C. of the binder resin of the toner, and the inclination angle with the toner of the image receiving layer is 40 degrees or less. It is characterized by using different polymers.

The toner used in the indirect dry full-color electrophotographic copying machine is required to have good melting property and color mixing property when heat is applied. Therefore, it is preferable to use a sharp-melting toner. . Considering the relationship with the image receiving layer of the electrophotographic transfer film, the binder resin of the toner is preferably a polyester resin. The toner can be produced, for example, by melt-kneading, pulverizing, and classifying a toner-forming material such as a binder resin such as polyester, a colorant (dye or pigment), and a charge control agent. The flow starting temperature of the binder resin of the toner used in the present invention is 75 to 90 ° C., which is lower than the flow starting temperature of the polymer of the image receiving layer by 0.5 to 10 ° C. Further, the difference between the flow starting temperature of the polymer of the image receiving layer and the flow starting temperature of the binder resin of the toner,
0.5-10 degreeC is preferable.

Next, the color image forming method will be specifically described. FIG. 6 is a schematic sectional view showing an example of an electrophotographic copying machine (apparatus) capable of forming a full-color image which can be used in the present invention. In an electrophotographic copying machine, a transfer material conveying system is provided from the lower side of the main body of the copying machine to a substantially central portion of the main body of the copying machine, and the transfer material conveying system is arranged in a substantially central portion of the main body of the copying machine. The latent image forming section is provided in the vicinity of the transfer drum 70, and the developing device is provided in the vicinity of the latent image forming section.

The transfer material conveying system is composed of supply trays 75 and 76 arranged on the lower side of the copying machine main body, and paper feed rollers 77 and 7 arranged substantially directly above the trays.
8 and sheet feeding guides 79 and 80 disposed in the vicinity of these sheet feeding rollers, and the transfer device 71 and the electrode 84 are disposed on the inner peripheral side. A transfer drum 70 that is freely movable, a transfer material separating charger 81 near the outer peripheral surface thereof, a contact roller 83 that is in contact with the outer peripheral surface thereof, a conveying device 73, and a conveying device 73. The fixing device 74 and the removable discharge tray 82 are provided.

The outer peripheral surface of the latent image forming portion is the transfer drum 7
An electrostatic latent image holding member (photosensitive drum) 90 which is arranged in contact with the outer peripheral surface of 0 and is rotatable in the arrow direction,
An image exposing unit such as a laser beam scanner or the like for forming an electrostatic latent image on the outer peripheral surface of the electrostatic latent image carrier, and a charger 98 disposed near the outer peripheral surface of the electrostatic latent image carrier. And a cleaning device 72, and a writing device 99 having image exposure reflection means such as a polygon mirror.

The developing device comprises a developer holding member 97 and a housing 96, and the electrostatic latent image holding member 9 is provided.
A black developing machine 92, a magenta developing machine 93, and a cyan developing machine for visualizing (that is, developing) the electrostatic latent image formed on the outer peripheral surface of the electrostatic latent image holder at a position facing the outer peripheral surface of 0. It has a 94 and a yellow developing machine 95.

An image forming sequence by the electrophotographic apparatus having the above configuration will be described by taking the case of the full color mode as an example. When the electrostatic latent image holder 90 described above rotates in the direction of the arrow, the surface of the electrostatic latent image holder is charged by the charger 9.
8 is uniformly charged. When the charging device 98 performs uniform charging, an electrostatic image is formed on the electrostatic latent image holding member 91 through the writing device 99 by the laser light modulated by the black image signal of the document (not shown). The black developing machine 92 develops the electrostatic latent image. On the other hand, from the supply tray 75 or 76 to the paper feed roller 77.
Or 78, the transfer material (transferred film for electrophotography) conveyed through the paper feed guide 79 or 80 is electrostatically transferred to the transfer drum 70 by the electrode 84 facing the contact roller 83. Wrapped around. Transfer drum 70
Are rotated in the direction of the arrow in synchronization with the electrostatic latent image holder 90, and the visible image (unfixed toner image) developed by the black developing device 92 is the outer peripheral surface of the electrostatic latent image holder 91. And the outer peripheral surface of the transfer drum 70 are in contact with each other, and are transferred by the transfer device 71. The transfer drum 70 continues to rotate and prepares for transfer of the next color (magenta in FIG. 6). On the other hand, the electrostatic latent image holding member 90 is destaticized by a destaticizing charger (not shown), cleaned by the cleaning device 72, and then recharged by the charger 98, as described above by the next magenta image signal. Receive a latent light. The electrostatic latent image formed by imagewise exposure with the magenta image signal is developed by the magenta developing device 93 and becomes a visible image. Subsequently, the above-described process is carried out for cyan color and yellow color respectively, and when the transfer of four colors is completed, the multicolor image formed on the transfer material is discharged by the charger 81. Then, the sheet conveying device 73 sends the sheet to the fixing device 74, and a series of full-color image forming sequence is completed even if fixing is performed by heat and pressure.

The main part of the fixing device 74 is composed of a heat roll 74a and a pressure roll 74b having the same structure. The heat roll 74a has 50 inside.
A substrate roll provided with a 0 W Colts lamp and formed of a steel core material having an outer diameter of 44 mmφ, and a rubber hardness provided on the substrate roll via an appropriate primer according to JIS.
It is composed of a fluorine-based rubber having a hardness of 60 degrees and a thickness of 40 μm (for example, Viton rubber manufactured by DuPont). On the other hand, the pressure roll has the same configuration, and uses a substrate roll formed of a steel core material having an outer diameter of 48 mmφ and an inner elastic layer having a thickness of 1 mm made of silicon rubber provided on the substrate roll. Except for, the configuration is exactly the same.

The heat roll is supplied with a release agent composed of dimethylpolysiloxane containing a functional group (for example, amino group) in order to modify the surface of the fluororubber into a high release surface. As a means, an oil donor roll made of silicone rubber is in contact. The oil donor roll is supplied with a release agent by an oil pickup roll immersed in an oil pan. The heat roll 74a and the pressure roll 74b are brought into pressure contact with each other by a pressurizing mechanism, and 6 m at the central portion.
A nip width of m is formed. Further, both rolls are set to have a surface temperature of 150 ° C. and are configured to rotate in a direction of an arrow at a surface speed of 60 mm / sec.

However, the indirect dry type full-color electrophotographic copying machine used in the present invention is the one shown above (FIG. 6).
Not only that, the electrostatic latent images corresponding to the respective colors sequentially formed on the image carrier are sequentially developed with the toners of the respective colors, and the developments are electrostatically sequentially superposed on the belt-shaped intermediate transfer member to form a primary image. At the same time as the transfer, the toner images multiply transferred onto the intermediate transfer member are secondarily transferred onto a recording medium by a bias transfer roll to which a transfer voltage having a polarity opposite to the charging polarity of the toner is applied. An indirect dry full-color electrophotographic copying machine that forms an image and the process of developing with multiple developing devices are performed multiple times to form a multicolor image on the image carrier, and the multicolor image is formed on the recording medium. On an indirect dry full-color electrophotographic apparatus that transfers a batch of images onto a recording medium to which a plurality of image carriers are juxtaposed and the images formed on the image carriers are conveyed to a transfer belt. To the color image It can also be used indirect dry full-color electrophotographic copying machine for performing the formation.

[0046]

【Example】

Example 1 A 100 μm-thick polyethylene terephthalate film heat-fixed by biaxial stretching was subjected to corona discharge treatment to prepare a coating solution for forming an image receiving layer having the following composition.

[Image-Receiving Layer Forming Coating Liquid] * Aqueous dispersion of polyester resin having the following composition: 75 parts by weight (solid content: 20% by weight) Crosslinking PMMA matting agent: 0.075 parts by weight (MR-7G; average particle size) Diameter: 7 μm, Soken Chemical Co., Ltd. Surfactant 0.13 parts by weight (Sandet BL, Sanyo Kasei Co., Ltd., solid content 44.6% by weight) Pure water 24.8 parts by weight

* The above polyester resin composition is shown in Table 1.

[0050]

[Table 1] Table 1 ──────────────────────────────────── Polyester composition (mol%) Number average Weight average T _fb contact IP NDC SSIA EG TEG BA Molecular weight Molecular weight Angle (Mn) (Mw) ─────────────────────────────── ────── 10.0 90.0 10.0 20.0 60.0 10.0 2130 3670 88.0 34 ────────────────────────────────── --Note) TP: terephthalic acid unit, IP: isophthalic acid unit, NDC: naphthalene dicarboxylic acid unit, SSIA: 5-sodium sulfoisophthalic acid unit, EG: ethylene glycol unit, TEG: triethylene glycol unit, B
A: Monoethylene oxide adduct unit of bisphenol A Preparation of aqueous dispersion of polyester resin having the above composition While stirring 200 g of the above polyester in 800 g of distilled water heated to 90 ° C with a disper (1000 rp
m), and stirring was continued at this temperature for 3 hours to obtain an aqueous polyester resin dispersion.

The above image receiving layer forming coating solution was applied onto one surface of the above polyethylene terephthalate film using a bar coater # 12 at an application rate of 105 m / min.
It was dried at 20 ° C. for 1 minute. The layer thickness was 3.0 μm.

[Coating Liquid for Forming Conductive Undercoat Layer] Water-soluble acrylic resin 1.55 parts by weight (JULIMER ET-410; manufactured by Nippon Pure Chemical Co., Ltd.) 1.80 parts by weight tin dioxide (SN-88; average) Particle size = 88 nm; Ishihara Sangyo Co., Ltd.) Nonionic surfactant 0.125 parts by weight (EMALEX / NP8.5; Nippon Emulsion Co., Ltd.) Pure water 96.4 parts by weight

The coating solution for forming the conductive undercoat layer was applied to the surface of the polyethylene terephthalate film on which the image receiving layer was not formed, using a bar coater # 2.4.
The coating was performed at a coating speed of 105 m / min and dried at 120 ° C. for 1 minute. The layer thickness was 0.15 μm.

[Coating Liquid for Forming Friction Coefficient Reducing Layer] 3.00 parts by weight of ethylene / methacrylic acid ionomer aqueous dispersion (Chemipearl S-120; manufactured by Mitsui Petrochemical Co., Ltd., solid content: 27% by weight) Crosslinked PMMA Matting agent 0.04 parts by weight (MR-2G-20-5; average particle size: 3 μm, manufactured by Soken Chemical Co., Ltd.) Low molecular weight polyolefin matting agent 0.165 parts by weight (Chemipearl W-100; average particle size: 3 μm, Mitsui Petrochemical Co., Ltd., solid content 40% by weight) Surfactant 0.077 parts by weight (Emarex NR8.5, Nippon Emulsion Co., Ltd.) Pure water 99.6 parts by weight

The coating liquid for forming the friction coefficient reducing layer was applied to the surface of the conductive undercoat layer using a bar coater # 2.4 at a coating speed of 105 m / min and dried at 120 ° C. for 1 minute. . The layer thickness was 0.4 μm.

Thus, a transfer film for electrophotography having an image receiving layer formed on one side of a polyethylene terephthalate film and a back layer consisting of a conductive undercoat layer and a friction coefficient reducing layer formed on the other side of the film. Created.

[Examples 2 and 3 and Comparative Example 1] An electrophotographic substrate was prepared in the same manner as in Example 1 except that the polyester resin for forming the image receiving layer shown in Table 2 was used. A transfer film was prepared.

[0058]

[Table 2] Table 2 ──────────────────────────────────── Polyester composition (mol%) Number average Weight average T _fb contact IP NDC SSIA EG TEG BA Molecular weight Molecular weight Angle (Mn) (Mw) ─────────────────────────────── ────── Example 2 10.0 90.0 10.0 40.0 40.0 10.0 2240 3910 93.9 35 Example 3 10.0 90.0 10.0 10.0 60.0 20.0 2110 3780 92.4 37 ────────────────── ────────────────── TP IP SSIA EG TEG BA COMPARATIVE EXAMPLE 1 90.0 10.0 10.0 20.0 60.0 10.0 2040 3750 78.7 43 ───────────── ───────────────────────

[Polyester Composition] The polyesters used in Examples 1 to 3 and Comparative Example 1 were obtained by an ordinary synthesis method. The compositions shown in Tables 1 and 2 were obtained by the proton method NM.
It was determined from the measured value by R.

[Number average molecular weight and weight average molecular weight] Table 1
The number average molecular weight and the weight average molecular weight shown in 2 and 2 were measured as follows. Gel permeation chromatography (SCL-6B, manufactured by Shimadzu Corporation) is used as a column of GPC for Shodex-K.
8 mg / m 2 using F804 at 40 ° C. while flowing the solvent (tetrahydrofuran) at a flow rate of 0.8 ml / min.
15 μl of a sample having a concentration of 1 (sample) / 20 ml (tetrahydrofuran) was injected. In addition, polystyrene was used as a standard substance.

The electrophotographic transfer film thus obtained was evaluated for its characteristics by the following methods.

(1) Preparation of toner To 96 parts by weight of a polyester resin (weight average molecular weight: 11000, number average molecular weight / weight average molecular weight: 2.9), 1 part by weight of a charge control agent and 3 parts by weight of a cyan pigment were added, Cyan toner was prepared by mixing. Magenta toner was prepared by adding 1 part by weight of charge control agent and 3 parts by weight of magenta pigment to 96 parts by weight of polyester resin in the same manner as cyan toner, and similarly 3 parts by weight of yellow pigment was used instead of 3 parts by weight of magenta pigment. To prepare a yellow toner, and 3 parts by weight of a black pigment in place of 3 parts by weight of a magenta pigment to prepare a black toner. The volume average particle diameters of these toners were all 7 μm. The volume average particle diameter of the toner is obtained by measuring the particle size distribution of particles having a particle diameter of 2 to 50 μm with a 100 μm aperture using a Coulter Counter TA-II type (manufactured by Coulter Co.). It was

(2) Toner Inclination Angle (degree) Using the toner obtained above, the toner inclination angle was measured in accordance with the measuring method. 1) Disk molding of toner or toner binder A tablet frame having a diameter of 13 m as shown in FIG. 7 of a tablet molding machine (Hand Press SSP-10 type, Shimadzu Corporation).
m, height 3.3 mm, the non-magnetic two-component toner is filled with the toner itself, and the magnetic one-component toner is filled with the binder resin, and a hand press applies a load of 1 ton for 1 minute. In addition, a disc as shown in FIG. 8 was molded. The above disc has a diameter of 13 mm and a thickness of 1.2.
mm, and weighed 183 mg.

2) Melting and solidification of the disk As shown in FIG. 9, the disk 103 is placed on the electrophotographic transfer film 102, and the toner disk is heated to 125 ° C. for 90 seconds to be melted. This laminated body was placed on an aluminum plate 101 having a thickness of 1 mm and a size of 420 mm × 297 mm for 1 minute to be rapidly cooled and solidified.

3) Measurement of Toner Inclination Angle Using a contact angle measuring device (manufactured by Kyowa Interface Science Co., Ltd.),
The angle between the film surface and the cutting line drawn to the toner at the contact point with the electrophotographic transfer film where the toner (disk) was solidified was measured on each of the left and right sides, and the average value was taken as the molten toner contact angle. The obtained values are shown in Tables 1 and 2 above.

(3) Flow Start Temperature The flow start temperatures of the polyester used as the image receiving layer of the electrophotographic transfer films obtained in the above Examples and Comparative Examples and the polyester as the binder resin of the toner were measured as follows. did. As a flow tester (see Fig. 4), a flow tester CFT-500 manufactured by Shimadzu Corporation
Temperature (time) and blanker 41 under the following conditions.
Was measured to determine the outflow start temperature. Measurement start temperature: 50 ° C, heating rate: 3.0 ° C / min,
Preheating time: 300 seconds, cylinder pressure: 10.0 kgf / cm ² , die: L = 1.00 mm, D = 1.00 mm, shear stress: 2.451 × 10 ^6.

(4) PE (Ratio of specularly transmitted light) Indirect dry full-color electrophotographic copying shown in FIG. 6 using the transfer films for electrophotography obtained in the above Examples and Comparative Examples and the toner obtained above. the machine, on the transfer film, the toner amount of the input halftone dot area rate of 100% portion, black 1.0 mg / cm ^2, and yellow, was adjusted to magenta and cyan 0.65 mg / cm ² deposition.
Then, patches with input halftone dot area ratios of 100% and 36% of yellow, magenta, and cyan toners are output as an unfixed image, and this unfixed toner image is heated to a fixing roller temperature 14
A full-color fixed image was formed on the transfer film by heating and pressing under the conditions of 5 ° C. and an average heating time of 60 msec. Input halftone dot area ratio of the obtained fixed image is 100%
(Cin 100%) part and input halftone dot area ratio 36% (Ci
n36%) Proportion of regular transmitted light (Projection Efficienc
y; hereinafter referred to as PE) was measured. Since the same result was obtained for each color, only the yellow result is shown in Table 2. The ratio PE of the specularly transmitted light is 2 ° field of view as a color matching function, A light source is used as standard light, and the angle of view of the aperture of the integrating sphere is 7 °.
The specular photometer was used to measure the regular transmittance and the diffuse transmittance, which were determined by the following formula. PE = log [{P (λ) + N (λ)} / n] / log {ΣP
(Λ) / n｝ where λ represents wavelength, P (λ) represents specular transmittance at wavelength λ, N (λ) represents diffuse transmittance at wavelength λ, and n is sampling in the visible light region. Represents a number. That is, the larger the PE, the more specularly transmitted light components, and thus the more vivid the projected image by OHP. As for the relationship between the PE value (%) and the visual evaluation of the projected image, it was found that if the PE value was 75% or more, the color reproducibility of the projected image was excellent.

(5) Offset In the heat fixing of (4) above, the presence or absence of offset was observed. And it evaluated as follows. AA: No offset is observed BB: The fixed image (image receiving layer) is slightly floating CC: The image receiving layer is moving to the fixing roll

(6) Toner transfer property With respect to ten obtained copy films, yellow (Y), magenta (M), cyan (C) and black (K) input halftone dot area ratio 100% (Cin 100%) part The optical density in the optical densitometer (X-Rite310
TR, manufactured by X-Rite) to evaluate the degree of transfer of the toner image. The larger the value, the better.

[Comparative Example 2] As a binder resin (polyester resin) of the toner, a toner having T _fb higher than T _fb of the image receiving layer of 95.5 ° C was used to prepare a toner in the same manner as above, and this toner was used. Then, in the same manner as in (4) PE above, toner was fixed on the electrophotographic transfer film of Example 1 to form a full-color fixed image. (4) to (6) above
Was evaluated.

The measurement results are shown in Table 3 below.

[0072]

[Table 3] Table 3 ──────────────────────────────────── Evaluation items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 ───────────────────────────────────── Image-receiving layer polymer T _fb 88.0 93.9 92.4 78.7 88.0 Toner binder T _fb 85.5 85.5 85.5 85.5 95.5 Toner inclination angle (°) 34 35 37 37 43 38 ──── ──────────────────────────────── PE (%) Yellow-toner-, Cin = 100% part 87.5 88 .3 83.2 72.4 70.3 Yellow toner, Cin = 36% part 84.3 83.8 79.4 68.9 66.1 ─────────────── ────────────────────── Office Toner AA AA AA CC CC AA ───────────────────────────────────── Toner transfer density Y 1.28 1.24 1.21 1.19 1.03 M 1.24 1.24 1.19 1.23 1.08 C 1.09 1.11 1.04 1.02 0.96 K 1.14 1. 09 1.08 1.05 0.99 ───────────────────────────────────── In addition, 1 to 3 and T _{fb of} the toner itself used in Comparative Example 1, K = 86.7 ° C., Y = 85.9 ° C., M = 8.
It was 6.3 degreeC and C = 86.5 degreeC.

[0073]

The transfer film for electrophotography of the present invention is
As the polymer of the image receiving layer, the flow starting temperature is higher than the outflow starting temperature of the binder resin of the toner 0 to 10 ° C., and the inclination angle with the toner of the image receiving layer is 40 degrees or less, that is, the compatibility with the toner is obtained. It uses a good polymer.
This allows the toner to melt before fixing,
Since the image receiving layer is also softened so that the toner easily penetrates into the image receiving layer, it is possible to obtain an image with excellent characteristics in which both the coloring property and the offset phenomenon of the halftone image portion of the projected image are improved. You can Needless to say, the electrophotographic transfer film of the present invention is also useful as a conventional monochromatic electrophotographic transfer film. In addition, by using a binder resin toner having a specific flow start temperature, the binder resin toner of the toner is 0 to more than the outflow start temperature.
Projection on a transfer film for electrophotography by the method of the present invention for forming a color image on the transfer film for electrophotography having an image receiving layer using a polymer having a flow start temperature of 10 ° C. higher. It is possible to form a color image having excellent color developability in the halftone image portion of the image.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of the basic configuration of a transfer film for electrophotography of the present invention.

FIG. 2 is a schematic cross-sectional view showing another example of the basic structure of the electrophotographic transfer film of the present invention.

FIG. 3 is a schematic cross-sectional view showing another example of the basic configuration of the transfer film for electrophotography of the present invention.

FIG. 4 is a schematic cross-sectional view showing an elevation type flow tester used for measuring the outflow starting temperature of the present invention.

FIG. 5 is a graph showing the relationship between the temperature and the amount of drop of the blanker, which is obtained by using the elevation type flow tester.

FIG. 6 is a schematic cross-sectional view of an example of an electrophotographic copying machine capable of forming a full-color image that can be used in the present invention.

FIG. 7 is a schematic cross-sectional view showing a tablet molding machine used for preparing a sample (toner disk) for measuring the contact angle between the image receiving layer and the toner of the electrophotographic transfer film of the present invention.

FIG. 8 is a perspective view showing the shape of a toner disk produced by a tablet molding machine.

FIG. 9 is a schematic cross-sectional view showing a state in which the toner disk is placed on an aluminum plate in order to rapidly solidify the toner disk.

[Explanation of symbols]

 11, 21, 31 Transparent support 12, 22a, 22b, 32a, 32b Image receiving layer 33a, 33b Conductive undercoat layer 41 Blanker 42 Mercury thermometer 43 Heating cylinder part 44 Sample filling part 45 Pressing screw 46 Pressing body 47 Die 70 Transfer drum 71 Transfer device 72 Cleaning device 73 Conveying device 74 Fixing device 75, 76 Supply tray 77, 78 Paper feeding roller 79, 80 Paper feeding guide 81 Transfer material separating charger 82 Discharging tray 83 Contact roller 84 Electrode 91 Electrostatic Latent Image Holder (Photosensitive Drum) 92 Black Developer 93 Magenta Developer 94 Cyan Developer 95 Yellow Developer 96 Housing 97 Developer Holder 98 Charger 99 Writing Device 101 Aluminum Plate 102 For Electrophotography Transferred film 103 Disc

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Hosui 2274 Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd.Ebina Business Office (72) Inventor Katsumi Harada 2274, Hongo, Ebina City, Kanagawa Prefecture Fuji Xerox Co., Ltd. Ebina Business In-house (72) Inventor Fumiyuki Suzuki 200, Onakazato, Fujinomiya-shi, Shizuoka Prefecture Fuji Photo Film Co., Ltd.

Claims (5)

[Claims] 1. A transparent support on at least one surface thereof,
A transfer film for electrophotography, comprising an image receiving layer made of a polymer capable of forming an image by heat fixing of a toner made of a coloring material and a binder resin,
The flow starting temperature of the binder resin of the toner to be fixed is 75 to 90 ° C., the flow starting temperature of the polymer of the image receiving layer is 0 to 10 ° C. higher than the flow starting temperature of the binder resin of the toner to be fixed, A transfer film for electrophotography, wherein the inclination angle of the toner with respect to the image receiving layer is 40 degrees or less. 2. The electrophotographic transfer film according to claim 1, wherein the polymer in the image receiving layer has a flow initiation temperature of 80 to 95 ° C. 3. The difference between the flow starting temperature of the polymer of the image receiving layer and the flow starting temperature of the binder resin of the toner is
The transfer film for electrophotography according to claim 1, which has a temperature of 0.5 to 10 ° C. 4. The electrophotographic transfer film according to claim 1, wherein the image receiving layer has a layer thickness of 1 to 4 μm. 5. The following steps (1) to (3): (1) a step of imagewise exposing the surface of the photoconductor to form a latent image, (2) the latent image of the latent image and a flow starting temperature. 75-90 ° C
The step of developing with one of two or more types of toner for forming a color image composed of the binder resin of (1) above to form an image on the surface of the photoconductor, and (3) the image on a transparent support, The image-receiving layer of a transfer film for electrophotography, which comprises a polymer having a flow-starting temperature which is 0 to 10 ° C. higher than the flow-starting temperature of a binder resin of a toner and has an inclination angle with the toner of 40 ° or less. After the color image is transferred onto the electrophotographic transfer film by repeating the step of transferring the toner onto the electrophotographic transfer film, the transfer image of the toner is fixed to the fixing temperature of the toner. A color image forming method comprising forming a color image on the transfer film for electrophotography by pressing with.