JPH09204110A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of executing a quick start, even if a thick film fixing belt is used by providing a second heating means for heating the belt in a part nearer to the upstream side than a nipping part. SOLUTION: This heating device is provided with a first heating means 20, the belt 25 sliding with the first heating means 20 and a pressure member 24 for forming the nipping part together with the belt 25. A heated material P is held/carried by the belt 25 and the pressure member 24, to heat the heated material P. This device is provided with the second heating means 30 for heating the belt 25 in the part nearer to the upstream side than the nipping part. The second heating means (subheater) 30 is composed of the same member as the first heating means (main heater) 20, that is, a subheater supporting body 31, a sub-plane substrate 32, a subheading resistor 33 and a subthermistor 38 in the same way as the main heater 20. The second heating means 30 is constituted to come into press-contact with the outside surface of the fixing belt 25 by an energizing means, to heat the outside surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image heating apparatus for heating a toner image and an image forming apparatus such as a copying machine, a printer and a FAX.

[0002]

2. Description of the Related Art Conventionally, a heat roller fixing system has been widely used as a means for fixing a toner image on a recording paper. However, this heat roller fixing method has a problem that it takes a long warm-up time until the heat roller reaches a predetermined fixing temperature.

Therefore, the applicant of the present invention has filed Japanese Patent Laid-Open No. 63-313
No. 182, Japanese Patent Laid-Open No. 2-157878 and the like propose a fixing method using a heat resistant belt.

This system (hereinafter referred to as SURF system)
Provides a resistance heating layer on a substrate made of a material having a high thermal conductivity such as alumina, and applies heat to the unfixed image via a thin heat-resistant belt while pressing it with a heating roller to transfer the toner onto the recording material. Unlike the heat roller method, only the pressure contact part of the heating element and the pressure roller is heated, so the time to reach the fixing temperature is fast and preheating is not required. There is.

Therefore, the power consumption is lower than that of the heat roller method, and it has been widely accepted in the market.

However, when the color image is heat-fixed by using the SURF system, the following problems occur.

Since the color toner has a sharp melting property with a low softening point, it is easily affected by the unevenness of the paper which is the material to be heated, and the melting state of the toner is different between the concave portion and the convex portion.
A fixed image with a slight uneven gloss is output.

[0008] In a material to be heated in which several colors of color toners are superposed on an OHP sheet, the amount of heat applied between the upper layer toner and the lower layer toner is different, so that good color mixing is not performed and the OHP sheet is transparent. Sex is impaired.

Even if the fixing temperature is raised to solve the above problems, the desired effect cannot be obtained. However, neither of these problems occurs in the heat roller fixing device which is an elastic roller for both the fixing roller and the heating roller used in the conventional color image forming apparatus. From the above, in the SURF system, since the heating member which is a rigid body is brought into contact with the toner image via the heat resistant belt, whether the portion where the toner image comes into contact during fixing is an elastic body or a rigid body is fixed. It is considered that this problem is caused by the difference of. That is, as shown in FIG. 9A, when the elastic body comes into contact with the toner image and is fixed, the elastic body follows the height of the toner image and is deformed, so that heat is applied to the lower portion of the toner image. To melt. Further, as shown in FIG. 9C, since the elastic body follows the unevenness of the paper, a uniform molten state can be obtained for any toner. On the other hand, as shown in FIG. 9B, the fixing belt 25, which is a rigid body, contacts the toner image T,
When fixing is performed by heat from a resistance heating layer (not shown) formed on the substrate 22, the rigid body does not follow the height of the toner image, but contacts only the upper portion of the toner image, and heat is applied to the lower portion of the toner image. Does not melt and does not mix well. Further, as shown in FIG. 9D, since the rigid body does not follow the unevenness of the paper, uneven gloss occurs in the fixed image in the fixed image.

Therefore, when the color toner is fixed by using the SURF method, an elastic layer such as silicon rubber is formed on the surface of the heat resistant belt, and the belt is brought into close contact with the unfixed toner to fix the toner. It has been proposed to prevent it (Japanese Patent Laid-Open No. 4-240884).

[0011]

However, as described above, when the color toner is fixed by using the SURF method, if an elastic layer such as silicone rubber is formed on the surface of the heat resistant belt, the elastic layer is generally formed. Since it is made of a polymer compound or resin having a large heat capacity such as silicon rubber of 10 μm to 200 μm, even if the heater rises to a desired temperature, the pressure contact portion between the heating element and the pressure roller reaches a fixing temperature. There is a drawback that quick start becomes impossible because it does not exist.

It is an object of the first invention of the present application to provide a heating device capable of quick start even with a thick film fixing belt.

A second object of the present invention is to provide a heating device capable of performing efficient preheating by heating only the surface of the fixing belt that contacts the material to be heated.

A third object of the present invention is to provide a heating device capable of quick start, which favorably heat-fixes a sharp melt toner such as a color toner.

A fourth object of the present invention is to provide an image forming apparatus capable of instantaneously outputting a high quality color image without uneven glossiness in a minute area.

[0016]

The structure for realizing the object of the first invention of the present application is the first heating means and the first heating means.
The heating means has a belt that slides with the heating means and a pressure member that forms a nip portion with the belt, and the material to be heated is nipped and conveyed by the belt and the pressure member to heat the material to be heated. In the heating device for performing, there is provided a second heating means for heating the belt on the upstream side of the nip portion.

The structure for realizing the second object of the present invention is the above structure, wherein the second heating means heats the surface of the belt in contact with the material to be heated. On the device.

A third aspect of the present invention is a heating device characterized in that, in the above-mentioned configuration, the belt has at least one elastic layer. In these configurations, the second heating means is characterized by performing radiant heating using a halogen heater.

In the above structure, the outer surface of the belt is black.

Further, the second heating means is characterized in that the endless belt is also used as a roller member which is stretched around the belt.

Further, the second heating means is characterized by using an electromagnetic induction heating system.

These configurations are characterized by having energization control means for energizing the second heating means after energizing the first heating means.

In these configurations, the heat generation amounts of the first heating means and the second heating means are equal or the first heating means is made larger.

According to a fourth aspect of the present invention, a heating device having the above-mentioned configuration is provided as an image heating and fixing device for heating and fixing an unfixed image on a recording material. It is in the image forming apparatus.

The image forming apparatus described above has developing means for a plurality of colors.

The developer of this developing means is characterized by being formed by a suspension polymerization method, a seed polymerization method or a direct polymerization method.

The developer is formed in a core-shell structure in which an ester wax is coated with an outer shell resin.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus using the fixing device of this embodiment as an image heating device. The image forming apparatus of this embodiment is a laser scanning type.
It is an electrophotographic color printer.

Reference numeral 3 denotes a photoconductor drum made of an organic photoconductor or an amorphous silicon photoconductor, which is rotationally driven in a clockwise direction indicated by an arrow at a predetermined peripheral speed (process speed). The peripheral surface of the rotating photosensitive drum 3 is uniformly charged to a predetermined polarity and potential by the charging roller 4. Then, the charged surface is modulated in accordance with the time-series electric digital pixel signal of the target image information output from the laser optical box 8 and input from an image signal generator such as an image reader (not shown) or a computer ( By scanning exposure with the laser light 6 that has been turned on / off, an electrostatic latent image of image information is formed. Reference numeral 7 denotes a laser light reflection mirror, which deflects the output laser light 6 from the laser optical box 8 with respect to the photosensitive drum 3.

Reference numeral 5 denotes a developing device, which comprises a yellow color developing device 5Y, a magenta toner developing device 5M, a cyan color developing device 5C, and a black color developing device 5B.

Reference numeral 16 is an intermediate transfer drum. It is arranged in contact with or close to the photosensitive drum 3, and is rotationally driven in a pure direction with rotation of the photosensitive drum 3 at substantially the same peripheral speed as the photosensitive drum 3.

Then, formation of electrostatic latent images corresponding to the color-separated images of the target full-color image and toner development of the electrostatic latent images are sequentially executed on the rotary photosensitive drum 3, and the respective toners are developed. The images are sequentially superimposed and transferred to the intermediate transfer body drum 16, and a full-color toner image corresponding to the mirror image of the target full-color image is synthetically formed on the surface of the intermediate transfer body drum 16. A cleaner 12 cleans the surface of the photosensitive drum 3 after the toner image is transferred to the intermediate transfer drum 16.

A single transfer material P as a recording material is fed from the paper feed cassette 11 to the intermediate transfer body drum 16 by the paper feed roller 10, and the intermediate transfer body drum 16 is fed to the transfer material P. The mirror image full-color toner image on the 16 side is transferred by the transfer roller 9 to form a full-color toner image on the surface of the transfer material P. The transfer roller 9 transfers a toner image from the intermediate transfer drum 16 to the transfer material P by supplying an electric charge having a polarity opposite to that of the toner from the back surface of the transfer material P.

The transfer material P on which the full-color toner image has been transferred is separated from the intermediate transfer drum 16 and introduced into the SURF type image heating and fixing device 13, where the toner image is heated and fixed and is discharged to the paper discharge tray 14. To be done.

Next, the SUR as the heating device of this embodiment
FIG. 2 shows a schematic configuration diagram of the F-type image heating and fixing device 13.

In FIG. 2, the heat resistant belt 25 is an endless belt, and includes a driving roller 26 and a driven roller 27.
And a heater that is fixedly supported by the heater support 21 and disposed below the rollers, and is suspended between the three members that are parallel to each other.

The driven roller 27 also serves as a tension roller for the belt 25, and the belt is conveyed in a clockwise direction at a predetermined speed as the drive roller is driven to rotate in the clockwise direction in the figure, that is, from the image forming portion side (not shown). The unfixed toner image T is rotatably driven without wrinkles, meandering, or speed delay at the same peripheral speed as the conveying speed of the recording material P as a heated member having the upper surface carrying the unfixed toner image T.

The pressure roller 24 is a roller having a rubber elastic layer having a good releasability such as silicon rubber, and the belt 2
5 is sandwiched by the descending belt portion 5 and is brought into opposing pressure contact with the lower surface of the first heating member (hereinafter referred to as the main heater) 20 by an unillustrated urging means with a contact pressure of, for example, a total pressure of 4 to 10 kg. Yes, the recording material P rotates counterclockwise, which is the forward direction in the conveying direction.

Next, the fixing belt 2 used in this embodiment
5 will be described.

FIG. 3 is a schematic diagram of a layer structure of an example of a composite layer belt as the whole belt, and this example is a two-layer structure belt suitable for fixing color toner. Reference numeral 25a is a heat-resistant layer as a base layer (pace belt) of the fixing belt, 25b is an elastic layer laminated on the outer surface of the heat-resistant layer 25a (the surface facing the toner surface image), and 25c is laminated on the outer surface of the elastic layer 25b. Is a release layer (surface layer).

The heat-resistant layer 25a is made of, for example, a highly heat-resistant resin belt made of polyimide, polyetheretherketone (PEEK), polyethersulfone (PES), polyetherimide (PEI), polyparabanic acid (PPA), or the like.
Metals such as i, SUS, and Al that have excellent strength and heat resistance can be used.

The elastic layer 25b is made of a heat-resistant elastic material such as silicone rubber, urethane rubber, or fluororubber. In this example, the silicone rubber having a thickness of 300 μm (hardness 40 ° ASKER) is used.
-C). This layer preferably has a thickness of 100
It is μm to 500 μm and hardness is 15 to 60 °. further,
It is also possible to improve the thermal conductivity by adding a ceramic filler or the like to the elastic layer 25b.

The release layer 25c may be made of a fluororesin such as PTFE (polytetrafluoroethylene), PFA, FEP or the like if only the black toner image is fixed.

The resistance value of the surface of the release layer 25c may be lowered by a method of mixing a conductive agent such as carbon black, graphite or conductive whiskers. In that case, charging of the toner contact surface of the fixing belt 25 can be prevented. When the toner contact surface of the fixing belt 25 is insulative, the surface of the fixing belt is charged and disturbs the toner image on the sheet P, or the toner image is transferred to the fixing belt 25 (so-called charging offset). In some cases, this problem can be solved by reducing the resistance of the release layer. In particular, the release layer 25
The surface resistance of c is preferably 10 ¹⁰ Ω or less.

The fixing belt 25 is not limited to the three-layer structure as described above, but may have a two-layer structure in which at least the surface in contact with the toner image is a silicone rubber layer, and if necessary, a filler / filler. It is also possible to prepare a single-layer belt of silicone rubber that has been subjected to strength-enhancing treatment by blending the above.

Generally, in fixing a color image, a fixed image having high gloss is often required in terms of color reproducibility and appearance. The belt heating method of the present embodiment is particularly effective for fixing a color image requiring such high image glossiness,
High glossiness can be obtained by making the surface of the fixing belt 25 (the surface of the recording material in contact with the toner image) less rough. Conversely, by roughening the surface of the fixing belt 25, it is possible to obtain an image with less gloss.

Such a difference in the surface state may be roughened by blasting or the like after the fixing belt is prepared. To make the surface smooth, the fixing belt is prepared by forming a fixing belt using a conventionally known inner mirror surface molding die. This can be done by a method such as finishing the surface to have high smoothness, but the method is not particularly limited to this.

The flat substrate 22 of the main heater 20, which is the first heating member, is made of a material having high thermal conductivity and high electrical resistivity, such as alumina, and has a thickness of 0.6 mm and a width of 10 mm, for example.
The resistance heating element 23 is provided in the longitudinal direction on the surface in contact with the belt 25. For example, an electric resistance material such as Ag / Pd, PuO ₂ , Ta ₂ N or the like is applied in a linear or strip shape by screen printing or the like. In addition, power supply electrodes (not shown) are formed at both ends of the resistance heating element 23, and the resistance heating element generates heat over the entire length by energizing between the electrodes.

The heater support 21 is, for example, phenol resin, PPS (polyphenylene sulfide), PAI.
(Polyamide imide), PI (polyimide), PEEK
(Polyether ether ketone), a high heat resistant resin such as a liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass or the like.

The thermistor 28 is bonded to the side of the flat substrate 22 of the main heater 20 opposite to the heating element with an adhesive having high thermal conductivity, detects the temperature of the main heater, and transmits information about the temperature (not shown). It is transmitted to the temperature control device by the means, and the temperature of the main heater 20 is controlled.

Reference numeral 30 denotes a second heating member (hereinafter referred to as a sub-heater), which is composed of the same member as the main heater 20, and comprises a sub-heater support 31, a sub-planar substrate 32, a sub-resistance heating element 33 and a sub-thermistor 38. It has the same structure as the main heater 20 and presses and heats the outer surface of the fixing belt 25 by a biasing means (not shown).

Electric power is simultaneously input to the main heater 20 and the sub-heater 30 of the present embodiment, and the time required for actually fixing the three-color image is measured, and the results are shown in Table 1.

[0053]

[Table 1]

In Table 1, as in the examples of
By heating the outer surface of the fixing belt 25 with the sub-heater 30, the time required for fixing is significantly shortened as compared with the embodiment. Since the fixing belt 25 has a relatively large thickness of 300 μm, it takes a long time to fix the outer surface of the fixing belt 25 at the nip portion by heating only the main heater 20. On the other hand, by heating the outer surface of the fixing belt 25 using the sub heater 30, the temperature rises in a short time. Moreover, even if the total electric power input to the main heater 20 and the sub-heater 30 is the same, it can be seen that the fixing time can be reached earlier by heating with two heaters from the front and back than when heating with one heater. In the case of, if the total power is 1000 W, the main heater: 700
W, sub-heater: When it is 300 W, fixing is possible in the shortest time.

In this embodiment, the fixing possible time is shown reduced for a three-color image, but it goes without saying that the fixing possible time can also be shortened for a single color image and a black toner image. In addition, the main heater 20 and the sub heater 30
The size, shape, etc. of may be different.

(Second Embodiment) This embodiment relates to the energization control of the main heater and the sub-heater. The control means for controlling the energization of the heater first starts up the main heater and then rises to the target temperature. , A structure for inputting electric power to the sub heater. Since the main heater is in the temperature control state after reaching the target temperature, the power that is lower than the startup power is input, so a relatively large amount of power is input to the sub-heater compared to the case of simultaneous input. it can. By adopting such a configuration, it is possible to further shorten the time until the fixing possible time is reached and reduce the maximum power of the entire apparatus. Further, the same effect can be obtained even if the sub-heater rises first.

(Third Embodiment) FIG. 4 shows a third embodiment.

In this embodiment, the halogen heater 40 is used as a sub-heater, and a part of the outer surface of the film is radiantly heated by the reflection shade 41. At this time, the outer surface of the fixing belt 25 is painted black in order to improve thermal efficiency.

(Fourth Embodiment) FIG. 5 shows a fourth embodiment, in which the tension roller 42 is formed of a roller-shaped heating body. The tension roller 42, which is a roller-shaped heating element, may be a ceramic tube or a glass tube having a resistance heating element wound around the surface thereof. (Fifth Embodiment) FIG. 6 shows a fifth embodiment in which a ceramic heater 50 is used as a sub-heater, and an endless belt 43 externally mounted on the ceramic heater 50 is interposed between the ceramic heater 50 and the outer surface of the fixing belt 25. It was made. With this configuration, the outer surface of the fixing belt 25 is not rubbed by the ceramic heater 50, so that the life of the fixing belt is extended.

(Sixth Embodiment) FIG. 7 shows a sixth embodiment in which electromagnetic induction heating is used as a sub-heater, and when electric power is input to the coil 53, electromagnetic (magnetic) induction is applied to the metal belt 51. Eddy current is generated and heat is generated. This heat heats the outer surface of the fixing belt 25.

(Seventh Embodiment) In this embodiment, a toner obtained by a polymerization method is used as a toner to be transferred onto a material to be heated. The method for producing the polymerized toner used in the present embodiment includes a method described in Japanese Patent Publication No. 56-13945, in which a molten mixture is atomized into the air using a disk or a multi-fluid nozzle to obtain a spherical toner, and Japanese Patent Publication No.
No. -10231, JP-A-59-53856,
A method of directly producing a toner by using the suspension polymerization method described in JP-A-59-61842, or a direct toner using an aqueous organic solvent in which a monomer is soluble but the obtained polymer is insoluble. Polymerization method such as dispersion polymerization method or soap-free polymerization method of directly polymerizing in the presence of a water-soluble polar polymerization initiator to produce a toner, or after preparing primary polar emulsion polymerization particles in advance, the opposite charge It is possible to manufacture a toner by using a hetero-aggregation method or the like in which polar particles having the above are added and associated.

However, in the dispersion polymerization method, the toner obtained has an extremely sharp particle size distribution, but the selection of materials to be used is narrow and the use of organic solvents affects the treatment of waste solvents and the flammability of solvents. From the viewpoint, the manufacturing device is complicated and easily complicated. The emulsion polymerization method represented by soap-free polymerization is effective because the particle size distribution of the toner is relatively uniform, but when the used emulsifier and initiator terminal are present on the surface of the toner particles, the environmental characteristics are easily deteriorated.

In the present invention, the suspension polymerization method under atmospheric pressure or under pressure is particularly preferable because it can relatively easily obtain a fine particle toner having a sharp particle size distribution. A so-called seed polymerization method in which a monomer is further adsorbed on the polymer particles once obtained and then polymerized using a polymerization initiator can also be suitably used in the present invention.

A more preferable toner used in the present embodiment is a toner tomographic surface measurement method using a transmission electron microscope (TEM), and in particular, a direct polymerization method in which an ester wax is encapsulated in an outer resin layer. It is manufactured. It is necessary to incorporate a large amount of ester wax into the toner from the viewpoint of fixability, and it is necessary to include the necessary ester wax in the outer shell resin. Unless the toner is not encapsulated, the toner cannot be sufficiently pulverized unless a special freeze-pulverization is used in the pulverization process, resulting in only a toner having a wide particle size distribution. This is extremely undesirable. In addition, in the case of freeze grinding, the equipment becomes complicated to prevent dew condensation on the equipment, and if the toner absorbs moisture, the workability of the toner is reduced, and it is necessary to add a drying step. It becomes a problem. As a specific method for encapsulating the ester wax, the polarity of the material in the aqueous medium is set to be smaller for the ester wax than for the main monomer, and a small amount of resin or monomer with a large polarity is added. As a result, a toner having a so-called core-shell structure (see FIG. 8) in which an ester wax is coated with an outer shell resin can be obtained. Toner particle size distribution control and particle size control are performed by changing the type and addition amount of sparingly water-soluble inorganic salts and dispersants that act as protective colloids, and mechanical device conditions such as rotor speed, number of baths, stirring blades. The toner according to the present exemplary embodiment can be obtained by controlling the stirring conditions such as the shape, the shape of the container, the solid content concentration in the aqueous solution, and the like.

As a specific method of measuring the tomographic plane of the toner in the present embodiment, the toner may be sufficiently dispersed in a room temperature curable epoxy resin and then cured in an atmosphere at a temperature of 40 ° C. for 2 days. Ruthenium tetraoxide,
If necessary, osmium tetroxide was also used for dyeing, and then a flaky sample was cut out using a microtome equipped with diamond teeth, and the tomographic morphology of the toner was measured using a transmission electron microscope (TEM). In this embodiment,
It is preferable to use the ruthenium tetroxide dyeing method in order to make a contrast between the materials by utilizing a slight difference in crystallinity between the ester wax used and the resin constituting the outer shell. A typical example is shown in the figure. Obviously, it was observed that the ester wax was encapsulated by the outer shell resin.

When the direct polymerization method is used in the toner manufacturing method of this embodiment, the toner can be specifically manufactured by the following manufacturing method. Ester wax, colorant, charge control agent, polymerization initiator and other additives are added to the monomer, and the monomer system is uniformly dissolved or dispersed by a homogenizer, ultrasonic disperser, etc., containing a dispersion stabilizer. It is dispersed in the aqueous phase to be used by a usual stirrer, a homomixer, a homogenizer or the like. Preferably, the stirring speed and time are adjusted so that the monomer droplets have the desired size of the toner particles, and the granulation is performed. Thereafter, by the action of the dispersion stabilizer, the particles may be stirred to such an extent that the particle state is maintained and the particles are prevented from settling. The polymerization is performed at a polymerization temperature of 40 ° C. or higher, generally 50 to 90 ° C. In addition, the temperature may be raised in the latter half of the polymerization reaction, and further, in the latter half of the reaction, or after the The aqueous medium may be partially distilled off later. After completion of the reaction, the generated toner particles are collected by washing and filtration, and dried. In the suspension polymerization method, the monomer system 1 is usually used.
It is preferable to use 300 to 3000 parts by weight of water with respect to 00 parts by weight as a dispersion medium.

When the toner is directly obtained by the polymerization method, the polymerizable monomer is styrene, o (m-, p).
Styrene monomers such as-)-methylstyrene and m (p-)-ethylstyrene; methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate,
Butyl (meth) acrylate, octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, dimethyl (meth) acrylate (Meth) acrylate monomers such as aminoethyl and diethylaminoethyl (meth) acrylate; and ene monomers such as butadiene, isoprene, cyclohexene, (meth) acrylonitrile, and acrylamide are preferably used.

In the present embodiment, in order to form the core-shell structure, it is essential to use a polar resin together, and the polar polymers and copolymers which can be used in the present embodiment are exemplified below. .

Polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl methacrylate, copolymers with styrene-unsaturated carboxylic acid esters, etc., nitrile monomers such as acrylonitrile, vinyl chloride etc. Halogen-containing monomers, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, other unsaturated dibasic acids,
Unsaturated dibasic acid anhydrides, polymers such as nitro monomers or copolymers with styrene monomers, polyesters,
Epoxy resin etc. are mentioned. More preferred are a copolymer of styrene and (meth) acrylic acid, a maleic acid copolymer, a saturated polyester resin, and an epoxy resin.

Examples of the polymerization initiator include 2,2'-
Azobis- (2,4-dimethylvaleronitrile), 2,
2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2 '
-Azobis-4-methoxy-2,4-dimethylvaleronitrile, azo-based or diazo-based polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butylhydro Peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis (4,4-t-butylperoxycyclohexyl) propane, tris- (t-butylperoxy) Peroxide-based initiators such as triazine, polymer initiators having a peroxide in the side chain, persulfates such as potassium persulfate and ammonium persulfate, and hydrogen peroxide are used.

The polymerization initiator is 0.5 to 20 of the polymerizable monomer.
The addition amount is preferably in parts by weight, and may be used alone or in combination.

In the present invention, in order to control the molecular weight, known crosslinking agents and chain transfer agents may be added, and the preferable addition amount is 0.001 to 15 parts by weight. In the present embodiment, any suitable stable dispersion medium can be used in the production of the polymerization toner by emulsion polymerization, dispersion polymerization, suspension polymerization, seed polymerization, a polymerization method using a hetero-aggregation method, or the like. Use agents. For example, as the inorganic compound, tricalcium phosphate, magnesium phosphate, ammonium phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate. , Bentonite, silica, alumina and the like. As organic compounds, polyvinyl alcohol, gelatin, methylcellulose, methylhydroxypropylcellulose, ethylcellulose, sodium salt of carboxymethylcellulose, polyacrylic acid and its salts, starch, polyacrylamide, polyethylene oxide, poly (hydroxystearic acid-g-methacrylic acid) A methyl-eu-methacrylic acid) copolymer or a nonionic or ionic surfactant is used.

When the emulsion polymerization method or the heteroaggregation method is used, an anionic surfactant, a cationic surfactant, a zwitterionic surfactant and a nonionic surfactant are used. It is preferable to use 0.2 to 30 parts by weight of these stabilizers based on 100 parts by weight of the polymerizable monomer.

When an inorganic compound is used among these stabilizers, a commercially available product may be used as it is, but the inorganic compound may be produced in a dispersion medium in order to obtain fine particles.

For fine dispersion of these stabilizers, 0.001 to 0.1 part by weight of surfactant may be used. This is to promote the intended action of the dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate,
Examples include sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like.

As the colorant used in the toner for polymerization in the present embodiment, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the colorant. It is better to perform a hydrophobizing treatment that does not inhibit the quality, for example, polymerization. In particular, many dyes and carbon blacks have polymerization inhibitory properties, so care must be taken when using them. As a preferable method for surface-treating the dye system, there is a method in which a polymerizable monomer is polymerized in advance in the presence of these dyes, and the obtained colored polymer is added to the monomer system. The carbon black may be treated with a substance that reacts with the surface functional group of the carbon black, such as polyorganosiloxane, in addition to the same treatment as the above-described dye.

In the present embodiment, the polymerized toner has the core-shell structure as shown in FIG.
Since the wax is contained inside, the member to be heated to which the polymerized toner has been transferred passes through the nip portion of the heating device of the present invention as shown in FIG. The wax adheres to the fixing belt 25 and further contacts the outer surface of the fixing belt 25.
Since the wax adheres to the fixing belt 25, the wax acts as a lubricant between the outer surface of the fixing belt 25 and the contact surface of the sub-heater 30 with the fixing belt 25, and the amount of wear of the fixing belt 25 and the sub-heater 30 is reduced. A longer life is realized.

[0078]

According to the invention of claim 1, since the belt entering the nip portion can be heated in advance, a heating device capable of quick start even when the belt is relatively thick is provided. it can.

According to the invention of claim 2, the belt is preheated only on the surface in contact with the material to be heated, so that the heating can be performed efficiently. Further, preheating can be performed regardless of the thickness of the belt. Further, it is possible to improve the fixing performance during continuous paper feeding.

According to the third aspect of the present invention, it is possible to provide a heat fixing apparatus capable of performing quick fixing of color toner without causing uneven gloss in a minute region and enabling quick start. According to the inventions of claims 4 and 5, it is possible to efficiently heat with a simple configuration.

According to the invention of claim 6, space can be saved and the life of the belt can be extended.

According to the invention of claim 7, it is possible to form a magnetic body that is heated by electromagnetic induction according to the shape of the heating surface of the belt to be heated, and it is possible to heat efficiently.

According to the inventions of claims 8 and 9, the time required for fixing can be shortened and the maximum power consumption of the entire apparatus can be reduced.

According to the tenth, eleventh, twelfth, and thirteenth aspects of the present invention, a high-quality color image that does not cause uneven gloss in a minute area is instantaneously output.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an image forming apparatus showing a first embodiment of the present invention.

2 is an enlarged cross-sectional view of a heating device provided in the image forming apparatus shown in FIG.

3 is a cross-sectional view showing a layer structure of a belt provided in the heating device of FIG.

FIG. 4 is a transverse cross-sectional view of a heating device showing a third embodiment.

FIG. 5 is a cross-sectional view of a heating device showing a fourth embodiment.

FIG. 6 is a transverse cross-sectional view of a heating device showing a fifth embodiment.

FIG. 7 is a transverse cross-sectional view of a heating device showing a sixth embodiment.

FIG. 8 is a transverse cross-sectional view of a heating device showing a seventh embodiment.

FIG. 9 is a diagram showing a heating state by a conventional heating device.

[Explanation of symbols]

3 ... Photosensitive drum 4 ... Charging roller 5M, 5Y, 5C, 5K ... Developing device 6 ... Laser light 7 ... Mirror 8 ... Laser optical box 9 ... Transfer roller 10 ... Paper feeding roller 11 ... Paper feeding cassette 12 ... Cleaner 13 ... Fixing device 14 ... Paper discharge tray 16 ... Intermediate transfer drum 20 ... Main heater 21 ... Support 22 ... Substrate 23 ... Heating element 24 ... Pressure roller 25 ... Fixing belt 26 ... Driving roller 27 ... Followed roller (tension roller) 28 ... Thermistor 30 ... Sub heater 31 ... Support 32 ... Substrate 33 ... Heating element 38 ... Thermistor 40 ... Halogen heater 41 ... Reflector 42 ... Roller heating element 43 ... Belt 50 ... Ceramic heater 51 ... Metal belt 52 ... Core 53 ... Coil T ... Toner P ... Transfer material

Claims (13)

[Claims] 1. A first heating means, a belt that slides on the first heating means, and a pressure member that forms a nip portion with the belt, and the belt and the pressure member cover the belt. In a heating device that heats a material to be heated by sandwiching and transporting the heating material, a second heating device that heats the belt upstream of the nip portion.
A heating device comprising: 2. The heating device according to claim 1, wherein the second heating means heats a surface of the belt that is in contact with a material to be heated. 3. The heating device according to claim 1, wherein the belt has at least one elastic layer. 4. The heating device according to claim 1, wherein the second heating means radiatively heats using a halogen heater. 5. The heating device according to claim 4, wherein the outer surface of the belt is black. 6. The second heating means according to claim 1,
A heating device characterized in that the endless belt is also used as a roller member which is stretched around. 7. The heating device according to claim 1, 2 or 3, wherein the second heating means uses an electromagnetic induction heating system. 8. The method according to claim 1, wherein
A heating device comprising an energization control means for energizing the second heating means after energizing the first heating means. 9. The method according to claim 1, wherein
A heating device characterized in that the amounts of heat generated by the first heating means and the second heating means are equal to each other, or that of the first heating means is larger. 10. An image forming apparatus comprising the heating device according to claim 1 as an image heating and fixing device for heating and fixing an unfixed image on a recording material. 11. The image forming apparatus according to claim 10, further comprising developing means for a plurality of colors. 12. The image forming apparatus according to claim 11, wherein the developer of the developing means is formed by a suspension polymerization method, a seed polymerization method or a direct polymerization method. 13. The image forming apparatus according to claim 12, wherein the developer is formed in a core-shell structure in which an ester wax is covered with an outer shell resin.