JP2821156B2 - Heat fixing method and heat fixing toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used in a fixing method for fixing a visible image formed with a toner on a recording material in electrophotography, electrostatic printing, magnetic recording and the like, and used in the fixing method. Related to toner.

[Conventional technology]

Conventionally, as a method of fixing a toner visible image to a recording material, an unfixed toner visible image is fixed by a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and pressing against the heating roller. A heat roll fixing method of heating the recording material holding the recording material while nipping and conveying the recording material is often used.

Also, a belt fixing system described in US Pat. No. 3,578,797 is known.

[Problems to be solved by the invention]

However, in the above-described conventional heat roller fixing, (1) there is a so-called wait time during which the image forming operation is prohibited until the heat roller reaches a predetermined temperature.

(2) The heating roller is maintained at an optimum temperature in order to prevent a fixing failure due to a change in the temperature of the heating roller due to the passage of the recording material or other external factors and a transfer of toner to the heating roller, that is, an offset phenomenon. Need
For this purpose, the heat capacity of the heating roller or the heating element must be increased, which requires a large amount of electric power and causes a rise in the temperature inside the image forming apparatus.

(3) When the recording material is discharged through the heating roller because the roller is at a constant temperature, the recording material and the toner on the recording material are cooled slowly, so that the toner has a high tackiness, May be offset, or a paper jam may occur due to the recording material being entangled.

(4) The configuration is such that the high-temperature heating roller is directly in contact with the hand, which causes a problem in safety or requires a protection member.

Further, even in the belt fixing method described in US Pat. No. 3,578,797, the above-mentioned problems (1) and (2) of heat roll fixing have not been fundamentally solved.

In Japanese Patent Application No. 62-144784 previously proposed by the present applicant, a toner visible image is heated via a heat-resistant sheet that is moved by a low-heat-capacity heating element that is energized and heated in a pulse form, and is fixed on a recording material. An image forming apparatus which has a short wait time and low power consumption depending on a fixing device to be used has been proposed. Similarly, in Japanese Patent Application No. 63-12069 previously proposed by the present applicant, in a fixing device for heating and fixing a visible image of a toner to a recording material via a heat-resistant sheet, the heat-resistant sheet has a heat-resistant layer. There has been proposed a fixing device having a release layer or a low-resistance layer to effectively prevent the offset phenomenon.

However, in order to achieve an excellent fixing method of toner visible images on a recording material, prevention of offset, etc., and a fixing method with a short wait time and low power consumption, in addition to the fixing device as described above, Greatly depends on the characteristics of the toner.

[Means for solving the problem]

A method of heating and fixing a visible image of a toner on a recording material, comprising: a) the toner contains 1 to 33% by number of toner particles having a particle size of 8 to 12.7 μm, and contains toner particles having a particle size of 16 μm or more; 2.0% by volume or less, the volume average particle diameter of the toner particles is 4 to 10 μm, and b) a fixedly supported heating element, and a recording material which is in pressure contact with the heating element via a fixing film, and And a pressure member for bringing the toner image into close contact with the heating member, and fixing the visible image of the toner on the recording material by heating. C) The pressing member is applied to the heating member via a fixing film. D) the surface temperature (T ₃ ) of the fixing film is higher than the maximum temperature (T _D ) of the endothermic peak of the toner measured by DSC. By peeling the fixing film from the fixing surface of the toner, the conventional Has proposed a fixing method in which the problems in the fixing method described above have been solved.

[Summary of the Invention]

The present invention relates to a method for heating and fixing a visible image of a toner on a recording material, comprising: a) the toner contains 1 to 33% by number of toner particles having a particle size of 8 to 12.7 μm, and has a particle size of 16 μm or more; B) the toner particles have a volume average particle diameter of 4 to 10 μm, and b) a fixedly supported heating element is opposed to and pressed against the heating element via a fixing film. And a pressure member for bringing the recording material into close contact with the heating member to heat and fix the visible image of the toner on the recording material. C) The pressing member is fixed to the heating member via a fixing film. The applied total pressure is 4 to 20 kg per 240 mm. D) The surface temperature (T ₃ ) of the fixing film is higher than the maximum temperature (T _D ) of the endothermic peak of the toner measured by DSC. It is characterized in that the fixing film is peeled from the fixing surface of the toner under temperature conditions. The present invention relates to a heat fixing method.

Further, according to the present invention, the visible image of the toner is recorded by a fixedly supported heating member and a pressing member which is pressed against the heating member and closely adheres the recording material to the heating member via a fixing film. The heating member is heated and fixed to the material, and the total pressure applied by the pressing member to the heating body via the fixing film is 4 to 2 per 240 mm.
0 kg, and the surface temperature (T ₃ ) of the fixing film is higher than the maximum temperature (T _D ) of the endothermic peak of the toner measured by DSC. A toner for heat fixing used in a heat fixing method for peeling, wherein the toner contains 1 to 33% by number of toner particles having a particle diameter of 8 to 12.7 μm, and has a particle diameter of 16 μm or more. And a toner having a volume average particle size of 4 to 10 μm.

(Detailed description of the present invention)

One feature of the constitution of the heat fixing method of the present invention is that the volume average particle diameter of the applied toner is 4 to 10 μm. As a result of intensive studies, the present inventors have found that the fixing method according to the present invention can be achieved by applying a toner having a particle size of 4 to 10 μm, which is smaller than the particle size that has been widely used conventionally. It was found that the fixing property was improved and an offset preventing effect was produced. This is not always clear,
The present inventors presume as follows.

That is, by setting the particle diameter of the toner particles to 4 to 10 μm, the arrangement of the toner particles in the toner visible image on the recording material before fixing is conventionally widely used as shown in FIG. In the case of the toner having a particle diameter (11 to 15 μm) (FIG. 1 (a)), the toner is arranged in a densely packed state with less unevenness on the surface and uniformity and relatively less air layer in the arrangement. Therefore, it is considered that the contact area between the toner particles is also increased.

If the toner layer that forms the visible image of the toner contains many air layers depending on the arrangement / aggregation state, the heat transfer efficiency in the toner layer is significantly reduced, and sufficient heat transfer is performed in the lower part of the toner layer. Therefore, a sufficient adhesive force cannot be obtained between the toner particles in the lower layer portion of the toner layer and the recording material, thereby deteriorating the fixing property or inducing an offset phenomenon. On the other hand, in the case of the present invention, the air layer contained in the toner layer is
The heat transfer from the heating element to the lower layer of the toner layer is performed efficiently by being reduced as compared with the toner having the conventional particle diameter, and the entire toner layer quickly becomes a molten state and exhibits good fixability. The offset phenomenon is less likely to occur.

FIG. 2 shows an unfixed toner visible image. When applied to an example of a fixing device that is preferable for use in the fixing method of the present invention, the toner particles quickly reach a molten state. At this time, the toner particles that are in contact with each other fuse almost simultaneously, so that a strong adhesive state is reached. If the adhesive strength is lower than the adhesive strength between the fixing member and the molten toner, an offset phenomenon occurs.

As in the present invention, the toner has a volume average particle diameter of 4 to
When the contact area between the toner particles is increased because the toner particles are as small as 10 μm, when the toner particles in contact with each other melt almost simultaneously, the adhesive force between the toner particles becomes larger as the contact area between the toner particles increases. It is considered that the fixing property is lowered and the offset phenomenon is suppressed because the toner becomes strong.

Such a remarkable difference in the fixing property and the offset phenomenon due to the aggregation and arrangement of the toner particles forming the visible image of the toner on the unfixed recording member is caused by the difference between the fixed and supported heating element in the present invention and the heating and heating. This has been observed in a heat fixing method in which a visible image of a toner is heat-fixed to a recording material by a pressing member which is in pressure contact with the body and presses the recording material against the heating member via a film. However, such a remarkable effect was not seen in the hot roll fixing which has been used more often than before. When the volume average particle size of the toner is larger than 10 μm, the above-mentioned effects cannot be sufficiently obtained, and
If the ratio is less than the above, there is a difficulty in toner productivity.

Another feature of the configuration of the heat fixing method of the present invention is 8
A toner containing 1 to 33% by number of toner particles having a particle size of 12.7 μm is used.

In an electrostatic latent image in an electrophotograph or the like, the electric field intensity at an edge portion around the latent image itself is higher than that at a central portion, so that the toner particles on the inside of the latent image become thinner than the edge portion, and toner on the recording material is removed. Also in the visible image, the toner inside the image is weakly mounted on the edge portion of the image, and the aggregation and arrangement state of the toner particles also has many irregularities on the surface, and it is likely to be in a disordered state with uneven density, The relationship between the state of aggregation and arrangement of toner particles and the fixability / offset phenomenon described above is disadvantageous in improving the fixability and preventing the offset phenomenon.

However, the present inventors have found that this problem can be solved by including 1 to 33% by number of toner particles having a particle size in the range of 8 to 12.7 μm. That is,
In the toner used in the present invention having a volume average particle diameter of 4 to 10 μm, it is considered that toner particles having a particle diameter in the range of 8 to 12.7 μm have a moderately controlled charge amount. Is supplied to the inner side where the electric field strength is smaller than that of the edge portion, thereby compensating for the small amount of the toner particles on the inner side with respect to the edge portion, thereby obtaining a toner visible image in which the toner particles are uniformly and densely gathered. Particle size 4 ~
The effect of improving the fixing property and preventing the offset development by the toner used in the present invention, which is 10 μm, is more effective.

1% by number of toner particles having a particle size in the range of 8 to 12.7 μm
If it is less than the above, the effect as described above cannot be obtained, and
If the amount is more than the number%, development beyond necessity, that is, excessive application of the toner on the recording material occurs, and the upper layer portion of the toner layer is in a molten state at the time of heating and fixing, but the lower layer portion is sufficiently transmitted with heat. Therefore, it is difficult to obtain a molten state, and the lower layer portion of the toner layer does not show sufficient adhesiveness, so that the fixing property is deteriorated and an offset phenomenon is easily caused.

Further, another characteristic of the heat fixing method of the present invention is 16 μm.
m is used, a toner containing 2.0% by volume or less of toner particles having a particle size of not less than m.

If the amount of toner particles having a particle diameter of 16 μm or more is more than 2.0% by volume, coarse toner particles of 16 μm or more protrude in a thin layer of toner particles developed on a latent image carrier in electrophotography or the like. By doing so, the delicate state of adhesion between the latent image carrier and the recording material via the toner layer is made irregular, causing a change in the transfer condition of the toner visible image from the latent image carrier to the recording material, and recording. The state of aggregation and arrangement of toner particles forming a toner visible image on the material is significantly disturbed, and the fixing performance is impaired, and an offset phenomenon is easily induced.

Therefore, toner particles having a particle size of 16 μm or more are 2.0% by volume.
The following is preferred, and it is preferable that the number is as small as possible.

Although the particle size distribution of the toner can be measured by various methods, in the present invention, the measurement was performed using a Coulter counter.

In other words, the Coulter Counter TA is used as a measuring device.
-Use type II (manufactured by Coulter), connect an interface (manufactured by Nikkaki) and a CX-1 personal computer (manufactured by Canon) that output the number distribution and volume distribution, and use primary sodium chloride as the electrolyte. Prepare 1% NaCl aqueous solution. As a measuring method, 0.1 to 5 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 2 to 20 mg of a measurement sample is further added. The electrolyte in which the sample was suspended was treated with an ultrasonic
After a dispersion treatment for minutes, the Coulter Counter TA-II
According to the mold, the particle size distribution of particles of 2 to 40 μ was measured on the basis of the number, using a 100 μ aperture as the aperture, and then the value according to the present invention was determined.

As the binder resin used in the toner of the present invention, the following binder resins for toner can be used.

For example, polystyrene, poly-p-chlorostyrene,
Styrene such as polyvinyltoluene and its substituted homopolymers; styrene-p-chlorostyrene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-acrylate copolymer, styrene -Methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone Styrene copolymers such as copolymers, styrene-butadiene copolymers, styrene-isoprene copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resins, naturally-modified phenolic resins, and naturally-modified maleic resins Acid resin, Le resin, methacrylic resin, polyvinyl acetate, silicone resins, polyester resins, polyurethane, polyamide resins, furan resins, epoxy resins,
Xylene resin, polyvinyl butyral, terpene resin,
Coumarone indene resin, petroleum resin and the like can be used.

In the toner of the present invention, it is preferable that a charge control agent is mixed (internally added) to the toner particles or mixed (externally added) with the toner particles before use. Examples of the positive charge control agent include denatured products such as nigrosine and fatty acid metal salts; quaternary ammonium salts such as tributylbenzylammonium-1-hydroxy-4-naphthosulfonate and tetrabutylammonium tetrafluoroborate; dibutyltin oxide and dioctyltin oxide And diorganotin oxides such as dicyclohexyltin oxide; diorganotin borates such as dibutyltin borate, dioctyltin borate and dicyclohexyltin borate can be used alone or in combination of two or more. Among these, charge control agents such as nigrosine and quaternary ammonium salts are particularly preferably used.

Also, the general formula R ₁ : H, CH ₃ R ₂ , R ₃ : a substituted or unsubstituted alkyl group (preferably C ₁
Homopolymers of monomers represented by -C _4); or styrene as described above, can be used acrylic acid esters, a copolymer of a polymerizable monomer such as methacrylic acid ester as a positive charge positive control agent, this In these cases, these charge control agents also have an action as (all or part of) the binder resin.

As the negative charge controlling agent that can be used in the present invention, for example, an organometallic complex and a chelate compound are effective, and examples thereof include aluminum acetylacetonate, iron (II) acetylacetonate, and 3,5-ditertiary. There are chromium butylsalicylate and the like, particularly preferred are acetylacetone metal complexes, salicylic acid-based metal complexes or salts,
Particularly, a salicylic acid-based metal complex or a salicylic acid-based metal salt is preferable.

The above-mentioned charge control agent (having no action as a binder resin) is preferably used in the form of fine particles. In this case, specifically, the number average particle diameter of the charge control agent is preferably 4 μm or less (more preferably 3 μm or less).

When internally added to the toner, such a charge control agent is used in an amount of 0.1 to 20 parts by weight (more preferably, 0.2 to 10 parts by weight) based on 100 parts by weight of the binder resin.
Parts by weight).

The toner of the present invention may optionally contain an additive. As the colorant, conventionally known dyes and pigments can be used, and usually 0.5 to 20 parts by weight based on 100 parts by weight of the binder resin may be used. Other additives include fluidity-imparting agents such as colloidal silica and aluminum oxide.

Further, the toner in the present invention may contain a magnetic material and be used as a magnetic toner. Examples of these magnetic materials include iron oxides such as magnetite, γ-iron oxide, ferrite, and iron-rich ferrite; metals such as iron, cobalt, and nickel; or metals such as aluminum, cobalt,
Examples include alloys with metals such as copper, lead, magnesium, tin, zinc, antimony, beryllium, bismuth, cadmium, calcium, manganese, selenium, titanium, tungsten, and vanadium, and mixtures thereof.

Further, the toner used in the present invention may contain various release agents as necessary. For example, polyfluorinated ethylene, fluororesin, fluorinated carbon oil, silicone oil, low molecular weight polyethylene, low molecular weight polypropylene, etc. are used in an amount of 0.1 to 10% by weight based on the toner.

To prepare the toner according to the present invention, a vinyl-based or non-vinyl-based thermoplastic resin, a pigment or dye as a colorant, a charge control agent, a magnetic powder, and other additives are mixed as necessary with a ball mill. After thoroughly mixing with a machine, a heating roll, a kneader, a pigment or a dye is dispersed or melted while melting and kneading and kneading using a hot kneader such as an extruder to make the resins compatible with each other, After cooling and solidifying, pulverization and strict classification are performed to obtain the toner according to the present invention.

The toner used in the heat fixing method of the present invention includes:
As a result of measurement in the measurement range from 10 ° C to 200 ° C using DSC,
The maximum value of the first endothermic peak (T _D ) is from 40 ° C to 12
A toner showing 0 ° C. is preferable, and a toner showing characteristics of 55 ° C. to 100 ° C. is more preferable.

Further, the temperature at which the film is peeled from the toner fixing surface is a temperature higher than the endothermic temperature, and is preferably 30 ° C. or more (more preferably 40 to 140 ° C.) than the endothermic temperature.
It is preferable to peel under high conditions.

In the present invention, the maximum value of the endothermic peak is measured according to ASTM D-3418-82. In particular,
10 to 15 mg of toner is collected and room temperature to 200 ° C under a nitrogen atmosphere
After heating at a heating rate of 10 ° C / min until then, hold at 200 ° C for 10 minutes, then quench, pre-treat the toner in advance, return to 10 ° C and hold at 10 ° C for 10 minutes. Heat to 200 ° C at a heating rate of / min and measure. In general, the data shown in FIG. 3 is obtained, and the maximum value of the endothermic peak that appears first is defined as the endothermic temperature (T _D ) in the present invention.

In the present invention, the heating element has a smaller heat capacity than a conventional heat roll and has a linear heating section, and the maximum temperature of the heating section is preferably 100 to 300 ° C.

Also, the film located between the heating element and the pressing member is
It is preferable to use a heat-resistant sheet having a thickness of 1 to 100 μm. Examples of the heat-resistant sheet include polyester, PET (polyethylene terephthalate), and PFA having high heat resistance.
(Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), polymer sheets such as PTFE (polytetrafluoroethylene), polyimide, and polyamide, metal sheets such as aluminum, and laminate sheets composed of metal sheets and polymer sheets Is used.

A more preferable film structure is that these heat-resistant sheets have a release layer and / or a low-resistance layer.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings, but this does not limit the present invention in any way.

FIG. 2A is a structural view of the fixing device of the present embodiment.

(11) is a low-heat-capacity linear heating element fixedly supported by the apparatus. As an example, a 1.0 mm-wide resistive material (13) is coated on a 1.0 mm-thick, 10 mm-wide, 240 mm-long alumina substrate (12). It is energized from both ends in the longitudinal direction. The energization is performed by applying a pulse having a pulse shape corresponding to a desired temperature and an energy release amount controlled by the temperature detecting element (14) with a pulse shape of 100 V DC and a cycle of 20 msec. The approximate pulse width is 0.5 msec to 5 msec. In this way, the fixing film (15) moves in the direction of the arrow in the drawing while coming into contact with the heating element (11) whose energy and temperature are controlled. As an example of the fixing film, a heat-resistant film having a thickness of 20 μm, for example, polyimide, polyetherimide, PES, PFA, at least on the image contact surface side
Release layer made by adding conductive material to fluororesin such as PTFE and PAF.
It is an endless film coated with μm. Generally, the total thickness is less than 100μ, preferably less than 40μ. The film is driven by the drive roller (16) and the conventional roller (17) and moved in the direction of the arrow without wrinkles due to tension.

(18) is a pressure roller having a rubber elastic layer having good releasability, such as silicon rubber, which presses the heating element through the film at a total pressure of 4 to 20 kg to rotate the film by pressure. Transfer material (19)
The unfixed toner (20) is guided to the fixing unit by the entrance guide (21) and obtains a fixed image by the above-mentioned heating.

Although the endless belt has been described above, as shown in FIG. 2 (b), a sheet feed shaft (24) and a take-up shaft (27) may be used, and the fixing film may be an endless film.

In addition, as an image forming apparatus, a copying machine, a printer, a fax,
This is applicable to all fixing devices that form an image using toner such as.

If the temperature detected by the temperature detection element (14) in the low heat capacity line heater (11) is T _1, the surface temperature T ₂ of the film (15) opposed to the resistance material (13) is about 10 than T ₁ 30 ℃ lower.
The film surface temperature T ₃ in the portion films (15) is peeled from the fixed toner surface is substantially equal to the temperature and the temperature T _2.

[Example 1] After mixing the above materials, the mixture is melt-kneaded by a twin-screw kneading extruder, cooled and solidified, finely pulverized and strictly classified, and 0.5% by weight of silica fine powder is added thereto to obtain a volume average particle size of 7.9 μm
A toner having a particle size distribution as shown in Table 1 was obtained.
The T _{D of} this toner was 71 ° C. Two-component developer A was prepared by mixing 1000 g of carrier iron powder with 100 g of this toner.

This two-component developer A is applied to a modified copying machine in which the fixing device of a commercially available copying machine NP-1215 (manufactured by Canon Inc.) is changed to the fixing device having the structure shown in FIG. Then, 200 images were output and evaluated.

In this fixing device, the temperature of the heating element surface temperature T ₁ of the heating element
The power consumption of the resistance material in the heating section at 190 ° C is 150 W, the total pressure of the pressure roller is 15 kg, and the nip between the pressure roller and the film is
3 mm, the fixing speed was set to 100 mm / sec, and as the heat-resistant sheet, a 20 μm-thick polyimide film having a low-resistance release layer obtained by adding a conductive substance to PTFE on the contact surface with the recording material was used. . At this time, the time required for the surface temperature of the heating body to reach 200 ° C. was about 2 seconds. Further, the temperature T _{1 at} this time was 176 ° C., and the temperature T ₂ was 174 ° C. Commercially available copying machine paper (54 g / m ² ) was used as the recording material.

As a result of image formation, clear and good images were obtained from the initial stage up to the 200th sheet, and no stain due to the offset toner was found on the surfaces of the fixing film and the pressure roller. In addition, it exhibited excellent fixability.

[Comparative Example 1] Instead of the toner used in Example 1, the volume average particle diameter was 10.7.
19.1% by number of particles having a particle diameter in the range of 8 to 12.7 μm, and toner particles having a particle diameter of 16 μm or more.
A two-component developer B was prepared in the same manner as in Example 1 except that a toner containing 2% by volume was used, and image formation evaluation was performed.

As a result, the fixing property was inferior to that of Example 1 from the initial stage to the 200th image.

Comparative Example 2 Two-component developers A and B used in Example 1 and Comparative Example 1, respectively.
Using a commercially available copier Canon NP-1215 (manufactured by Canon Inc.)
, And image formation was performed in the same manner as in Example 1, and the two-component developers A and B were compared and evaluated.

At this time, the fixing device is a hot roll type fixing device having a 900 W heater, and a roller for applying oil to the heat roller is in contact with the heat roller. When the set temperature of the heat roller surface temperature is 190 ° C, the time required for the heat roller to reach the set temperature and enable image forming operation is about 90
Seconds.

As a result of image formation, no significant difference in fixing property was observed between the two-component developers A and B. In addition, in both cases, the toner adhered to the roller for oil application in contact with the heat roller at substantially the same level, indicating that a slight amount of toner was offset.

[Example 2] From the above materials, a volume average particle size of 4.
A toner C containing 2.3% by number of toner particles having a particle diameter in the range of 4 μm and 8 to 12.7 μm and 0.0% by volume of toner particles having a particle diameter of 16 μm or more was obtained. The T _{D of} this toner C was 76 ° C.

The modified copier using the toner C in Example 1 was replaced with a selenium drum as the photosensitive member, the charging conditions were changed, and the modified copier was used to produce 200 images in the same manner as in Example 1. Performed and evaluated.

As a result, the obtained image showed good fixability and no offset was generated.

The time when the temperature of the temperature measuring element surface T _{1 of the} heating body reached 190 ° C. and the temperatures T ₂ and T ₃ were almost the same as those in Example 1.

Example 3 The same material as in Example 2 was used in the same manner as in Example 1, containing 17.5% by number of toner particles having a volume average particle size of 9.3 μm and a particle size in the range of 8 to 12.7 μm, and having a particle size of 16 μm or more. A toner D containing 0.6% by volume of toner particles having a particle size was obtained.
The T _{D of} this toner D was 67 ° C.

Using this toner D, the same image formation evaluation as in Example 2 was performed.

As a result, as in Example 1, both the fixing property and the offset resistance were good.

The time when the temperature of the temperature measuring element surface T _{1 of the} heating body reached 190 ° C. and the temperatures T ₂ and T ₃ were almost the same as those in Example 1.

Example 4 In the same manner as in Example 3, the volume average particle size was 8.7 μm,
29.7% by number of toner particles having a particle size in the range of 2.7 μm
To obtain a toner E containing 0.4% by volume of toner particles having a particle diameter of 16 μm or more. The T _{D of the} toner E
= 78 ° C.

Using this toner E, the same image formation evaluation as in Example 2 was performed.

As in Examples 1 and 2, an image having good fixability was obtained, and no offset occurred.

The heating element also had a time required for the surface temperature T _{1 of the} temperature measuring element to reach 190 ° C., and the temperatures T ₂ and T ₃ were almost equal to those in Example 1.

[Comparative Example 3] In the same manner as in Example 3, the volume average particle diameter was 9.5 µm,
38.8% by number of toner particles having a particle size in the range of 2.7 μm
To obtain a toner E containing 0.9% by volume of toner particles having a particle diameter of 16 μm or more.

Using this toner G, the same image formation evaluation as in Example 2 was performed.

As a result, the fixing property was inferior to those of Examples 2 and 3,
No image defects due to the offset phenomenon were observed,
It was found that there was slight toner adhesion on the pressure roller, and the offset phenomenon occurred although the amount was small.

〔The invention's effect〕

An object of the present invention is to provide a heat-fixing method which has good fixing properties, excellent offset resistance, low power consumption, quick start of a wait time in a very short time, and which also takes safety into consideration.

FIG. 1 (a) shows a case where a toner having a particle size that has been widely used in the past is used, and a large air layer exists between the toner particles. FIG. 1 (b) shows the case where a toner having a volume average particle diameter of 4 to 10 μm, which is relatively smaller than the conventionally used toner, is used as in the present invention. ) Compared to the figure, when the toner particles are densely filled, the air layer between the toner particles is small, the toner particles have many contact points, and the top layer of the toner layer has less irregularities. I have.

[Brief description of the drawings]

In the accompanying drawings, FIG. 1 (a) is a diagram schematically showing a cross section of an unfixed toner layer when a conventional toner is used.
FIG. 1B is a diagram schematically showing a cross section of an unfixed toner layer when the toner according to the present invention is used. FIG. 2A is a schematic sectional view of a fixing device for carrying out the fixing method of the present invention, and FIG. 2B is a sectional view for carrying out a fixing method of another embodiment of the present invention. FIG. 2 is a schematic sectional view of a fixing device. FIG. 3 is a graph showing the endothermic peak of the toner. 11 Heating element 12 Alumina substrate 13 Resistive material 14 Temperature sensor 15 Fixing film 16 Driving roller 17 Driven roller 18 Pressure roller 19 Recording material 20 To be determined Toner visible image 21 …… Entrance guide

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-68766 (JP, A) JP-A-59-33459 (JP, A) JP-A-63-73271 (JP, A) JP-A-58-1983 117553 (JP, A) JP-A-59-40651 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 9/08 G03G 15/20 101

Claims (3)

(57) [Claims] 1. A method for heating and fixing a visible image of a toner on a recording material, comprising: a) the toner contains 1 to 33% by number of toner particles having a particle size of 8 to 12.7 μm, and a particle size of 16 μm or more; B) the toner particles have a volume average particle diameter of 4 to 10 μm, and b) a fixedly supported heating element and a fixing film which is pressed against the heating element and pressed against the heating element. And a pressure member for bringing the recording material into close contact with the heating member via a fixing member. C) The heating member fixes the visible image of the toner on the recording material by heating. D) The surface temperature (T ₃ ) of the fixing film is higher than the temperature (T _D ) of the maximum endothermic peak of the toner measured by DSC. Peeling the fixing film from the fixing surface of the toner under high temperature conditions A heat fixing method characterized by the above-mentioned. 2. The fixing method according to claim 1, wherein when the fixing film is peeled off from the toner fixing surface, the surface temperature (T ₃ ) of the fixing film is higher than the maximum temperature of the endothermic peak of the toner by 30 ° C. or more. Method. 3. A recording medium, wherein a visible image of toner is formed by a fixedly supported heating element and a pressing member which is opposed to and pressed against the heating element and makes the recording material adhere to the heating element via a fixing film. The fixing member is heated and fixed, and the total pressure applied to the heating member by the pressing member through the fixing film is 4 to 20 kg per 240 mm, and the surface temperature (T ₃ ) of the fixing film is measured by DSC. A heat fixing toner used in a heat fixing method for separating the fixing film from a fixing surface of the toner under a temperature condition higher than a temperature (T _D ) of a maximum value of an endothermic peak of the toner, wherein the toner is Containing 1 to 33% by number of toner particles having a particle diameter of 8 to 12.7 μm, and containing 2.0% by volume or less of toner particles having a particle diameter of 16 μm or more, and having a volume average particle diameter of 4 to 4 μm. A heat fixing toner having a thickness of from 10 to 10 μm.