JPH0812456B2 - Heat fixing method and heat fixing capsule toner used in the method - Google Patents

Description

The present invention relates to a fixing method and a fixing method for fixing a visible image formed by a toner to a recording material in electrophotography, electrostatic printing, magnetic recording and the like. Regarding the toner used.

[Prior Art] Conventionally, as a method for fixing a visible image of a toner on a recording material, it is undetermined by using a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and being in pressure contact with the heating roller. A heat roll fixing method is often used in which a recording material holding a visible toner image is heated while being nipped and conveyed.

Also, a so-called belt fixing method described in USP 3,578,797 is known.

[Problems to be Solved by the Invention] However, in the above-described thermal roll fixing which has been frequently used, there is (1) a time for which the image forming operation is prohibited until the heat roller reaches a predetermined temperature, that is, a so-called wait time.

(2) The heating roller is set to an optimum temperature in order to prevent fixing failure and transfer of toner to the heating roller, which is so-called offset development, due to the temperature of the heating roller fluctuating due to passage of a recording material or other external factors. It is necessary to maintain this, and for this purpose, the heat capacity of the heating roller or the heating body must be increased, which requires a large amount of electric power.

(3) Due to the low temperature of the roller, when the recording material is discharged through the heating roller, the recording material and the toner on the recording material are cooled slowly, so that the adhesiveness of the toner becomes high, In combination with the curvature of the roller, a paper jam may occur due to the offset or winding of the recording material.

(4) When the high-temperature heating roller comes into direct contact with the hand, the structure becomes a problem and there is a problem in safety or a protective member is required. Also, in the belt fixing method described in USP 3,578,797, the problems (1) and (2) of the heat roll fixing described above have not been fundamentally solved.

An object of the present invention is to substantially eliminate the wait time for solving the above-mentioned problems, or an extremely short time,
Further, the present invention provides a novel heating and fixing method which has low power consumption, does not cause an offset phenomenon, and is excellent in fixing a toner image on a recording material.

Further, the object of the present invention is to provide a heat fixing toner which is preferably used in the heat fixing method provided in the present invention.

Still another object of the present invention is to provide a heat fixing method that does not require a heat resistant special bearing by not using a high temperature rotating roller.

Still another object of the present invention is to provide a heat fixing method which is excellent in safety or does not require a protective member by having a fixing device structure in which the high temperature body is not directly touched.

[Means and Actions for Solving the Problems] In Japanese Patent Application No. 62-147884 previously proposed by the present applicant, a heat-resistant sheet that moves by a heating element of low heat capacity that is energized and heated in a pulsed manner is used. An image forming apparatus having a short wait time and low power consumption has been proposed as a fixing device that heats a toner image and fixes it on a recording material. Similarly, Japanese Patent Application No. 63-1206 previously proposed by the applicant.
In 9, in the fixing device for heating and fixing the visible image of the toner on the recording material via the heat resistant sheet, the heat resistant sheet has a heat resistant layer and a release layer or a low resistance layer,
A fixing device has been proposed that effectively prevents offset development.

However, in order to realize a fixing method that has a short wait time and low power consumption while achieving excellent fixability of a toner image on a recording material, prevention of offset, etc., the fixing device as described above is used. In addition, the characteristics of the toner largely depend.

The present invention that achieves the above-mentioned object is a method of heat-fixing a visible image of a toner to a recording material by using a capsule toner in which a core particle surface containing a binder resin, a release agent, and a colorant as a main component is coated with the resin. In a), the binder resin contains a polyester resin obtained by copolycondensation of etherified bisphenols and a carboxylic acid having a valence of 2 or more, or an anhydride thereof or a lower alkyl ester thereof, and the polyester resin is , Melt viscosity η'by a thermal overhead flow tester is 50% at the outflow point 10
³ to 10 ⁵ poises and the natural logarithm (ln
η ′) is plotted against temperature, the capsule toner has the characteristic that the absolute value of the slope of the graph is 1.0 ln (poise) / ° C. or less, and b) a fixedly supported heating element. , A heating member which is brought into close contact with the heating body, heat-fixes the visible image of the toner on a recording material, and a film is formed on the toner-fixing surface at a temperature higher by 30 ° C. or more than the maximum value of the endothermic peak measured by DSC of the toner. The present invention relates to a heating and fixing method, characterized in that

Further, the fixed image of the toner is heated and fixed to the recording material by a fixedly supported heating element and a heating member which is in pressure contact with the heating element and brings the recording material into close contact with the heating element via a film. In a toner used in a heat fixing method of peeling a film from a toner fixing surface at a temperature of 30 ° C. or more higher than a maximum value of an endothermic peak measured by DSC, the toner contains a binder resin, a release agent, and a colorant. A capsule toner having a core particle surface as a main component coated with a resin, wherein the binder resin is a copolycondensation of etherified bisphenols and a carboxylic acid having a valence of 2 or more, or an anhydride thereof or a lower alkyl ester thereof. If the polyester resin contains a polyester resin that has a melt viscosity η'of 50% by an elevated thermal flow tester at an outflow point of 10 ³
~ 10 ⁵ poise and the natural logarithm of its melt viscosity ln
The present invention relates to a heat fixing capsule toner having a characteristic that the absolute value of the slope of the graph when η ′ is plotted with respect to temperature is 1.0 ln (poise) / ° C. or less.

 Hereinafter, the present invention will be described in detail.

The constitutional feature of the heat fixing method of the present invention is that a polyester resin obtained by copolycondensing an etherified bisphenol and a divalent or higher carboxylic acid or an anhydride thereof or a lower alkyl ester thereof as a core binder resin. The polyester resin contains a polyester resin having a melt viscosity η ′ of 10 ³ to 10 ⁵ poise at a flow point of 50% by a thermal overhead flow tester and a natural logarithm lnη of the melt viscosity in the temperature range. ′ Is plotted against temperature, the absolute value of the slope of the graph is 1.0 ln (poise) / ° C or less. By using a core material having such characteristics, it is possible to offset the film with extremely low power consumption. It is to be able to heat and fix the toner to the recording material without the need to measure the melt viscosity in the present invention by measuring the elevated flow tester (Shimadzu floater) as shown in FIG. Star CFT-500
Shape). 1.5g molded using a pressure molding machine
Apply a load of 10 kgf with a plunger at a constant temperature and push it out from a nozzle with a diameter of 1 mm and a length of 1 mm,
In this way, the plunger descent amount (flow rate) of the flow tester is measured.

This outflow rate is measured at each temperature (interval of 2.5 ° C), and the apparent viscosity η'can be obtained from this value by the following equation.

However, η ′: Apparent viscosity (poise) Tω ′: Apparent shear reaction of tube wall (dyne / cm ² ) Dω ′: Apparent shear rate of tube wall (1 / sec) Q: Outflow rate (cm ³ / sec = ml / sec) R: Extrusion pressure (dyne / cm ² ) [10kgf = 980 × 10 ⁴ dyn
e] B: Nozzle radius (cm) [0.1 cm] L: Nozzle length (cm) [0.1 cm] Plot of natural logarithm of apparent viscosity η'obtained from the flow tester against temperature (° C) Then, the slope at the temperature of the 50% pour point was calculated. The 50% outflow point is
Performed by the flow tester, heating the sample at a temperature rising rate of 4 ° C / m
It is the temperature at the time when the load of 10 kgf is applied while heating at in, and the outflow amount from the nozzle becomes 50 wt%.

In the present invention, the “slope” of the viscosity at the 50% pour point means, as shown in FIG. 5, the measurement points (t _c and t _d ) of the melt viscosity that sandwich the temperature (t ₅₀ ) at the 50% pour point. Connect the plots at the outer measurement points (t _a and t _b ) with a straight line, It is calculated from the above, and this is approximated and used as the “slope” of the slope. (However lnη _'a represents a value obtained by taking the natural logarithm of the viscosity at _{t a (℃), lnη'} b denotes a value at t _b (° C.). The measurement was measured 5 ° C. intervals.) The present invention The "viscosity" and "inclination" of the binder resin in the heat fixing method of 1 are peculiar to each binder resin,
It shows the sensitivity of the viscosity of the binder resin to temperature, and is involved in the binder property and toner particle deformation during the formation of a fixed image. Particularly in the fixing method using a film, the correlation with the fixing process is great. When the melt viscosity is 10 ⁵ poise or more, particle deformation during heat fixing does not easily occur and viscosity does not increase, which causes fixing failure, and a large amount of energy is required to compensate for this. On the other hand, when it is 10 ³ poise or less, bleeding on the transfer paper or penetration into the transfer paper is likely to occur. Also, if the “inclination” becomes too large (1.0 ln (poise) / ° C or more), the particles will show a rapid viscosity change due to temperature, and the latitude of the fixing temperature will not be sufficient, resulting in poor fixing or stains. Easy to get jammed. Furthermore, the dependency on the fixing processing speed (mm / sec) becomes large. This "tilt" is also involved in the viscosity change during cooling after melting the particles during fixing, and when the "tilt" is large, offset development on the film increases.

Further, etherified bisphenols are preferable as the alcohol component which is a constituent raw material of the polyester resin of the present invention, whereby impact resistance as a toner is maintained and electrophotographic characteristics other than fixability are not adversely affected.

Polyoxystyrene (6) is usable as the etherified diphenol which is a constituent raw material of the polyester resin as the binder resin of the capsule toner applied to the present invention.
-2,2-bis (4-hydroxyphenyl) propane,
Polyhydroxybutylene (2) -2,2-bis (4-hydroxyphenyl) propane, polyoxyethylene (3) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3) -bis (4 -Hydroxyphenyl) thioether, polyoxyethylene (2) -2,6-dichloro-4-hydroxyphenyl,
2 ', 3', 6'-trichloro 4'-hydroxyphenylmethane, polyoxypropylene (3) -2-bromo-
4-hydroxyphenyl, 4-hydroxyphenyl ether, polyoxyethylene (2,5) -PP-bisphenol, polyoxybutylene (4) bis (4-hydroxyphenyl) ketone, polyoxystyrene (7) -bis ( 4-hydroxyphenyl) ether, polyoxypentylene (3) -2,2-bis (2.6-diaiod-4)
-Hydroxyphenyl) propane and polyoxypropylene (2.2) 2.2-bis (4-hydroxyphenyl) propane.

One group of etherified diphenols are etherified bisphenols. A preferred group of etherified bisphenols are those that are ethoxylated or propoxylated, having 2-3 moles of oxyethylene or oxypyropyrene per mole of bisphenol and having R as a propylene or sulfone group. An example of this group is polyoxyethylene (2.5) -bis (2.6-dibromo-).
4-hydroxyphenyl) sulfone, polyoxypropylene (3) -2,2-bis (2.6-difluoro-4-)
Hydroxyphenyl) propane and polyoxytyryl (1.5) -polyoxypropylene (1.10.)-Bis (4-hydroxyphenyl) sulfone.

Another preferred group of etherified bisphenols falling into the group characterized by the above formula is polyoxypropylene 2.2 · 2′-bis (4-hydroxyphenyl) propane and polyoxyethylene or polyoxypropylene 2 ·.
2-bis ((4-hydroxy, 2.6-dichlorophenyl) propane (the number of oxyalkylene units is 2.1 to 2.5 per 1 mol of bisphenol) can be mentioned.

In addition, 2 which is a constituent raw material of the polyester resin of the present invention
As the carboxylic acid having a valency or higher, any of aromatic carboxylic acids and other carboxylic acids can be used, and 95 mol% or more of the acid component is preferably a dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid. Acid, diphenyl-P.P'-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, diphenylmethane-P.P'-dicarboxylic acid,
Aromatic dicarboxylic acids such as benzophenone-4,4'-dicarboxylic acid and 1,2-diphenoxyethane-P.P'-dicarboxylic acid can be used, and as other acids, maleic acid, fumaric acid, glital acid, Cyclohexanecarboxylic acid, succinic acid, malonic acid, adipic acid, mesaconic acid, citraconic acid, sebacic acid and their anhydrides and lower alkyl esterified products of these acids can be used.

Tricarboxylic or higher polycarboxylic acids can also be used, for example trimellitic acid, pyromellitic acid, cyclohexanetricarboxylic acids, 2.5 / 7-naphthalenetricarboxylic acid, 1.2 ・ 4-naphthalenetricarboxylic acid, 1.2 ・
4-Butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxylic propane, 1,3-dicarboxyl-2-methyl-2-methylenecarboxylic propane, tetra (methylenecarboxylic acid) ) Methane, 1,2,7,8-octanetetracarboxylic acid and their anhydrides and their lower alkyl ester compounds may be used in a small amount.

In addition, trihydric or higher polyols may be used in a small amount, and sorbitol, 1,2,3,6-hexanetitol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1, 2, 4-mesitatriol, glycerin, 2-
Methyl propanetriol, 2-methyl-1,2.4-
Examples include butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, erythro1,2,3-butanetriol, threo1,2,3-butanetriol.

As the releasing agent used in the present invention, polyfluorinated ethylene, fluororesin, fluorinated carbon oil, silicone oil, low molecular weight polyethylene, low molecular weight polypropolene, etc. is 0.1 to 20% by weight with respect to the core material, preferably 0.5 to Used at an addition amount of 10% by weight.

Furthermore, in the core material used in the present invention, in addition to the polyester resin composed of the above-mentioned constituent materials, the melt viscosity η'by the elevated flow tester is 50% or less at a ratio of 30% by weight or less of the polyester resin. Does not deviate from 10 ³ to 10 ⁵ poise, and the natural logarithm (ln
η ′) is plotted against temperature so that the absolute value of the slope of the graph does not exceed 1.0 ln (poise) / ° C., for example, a vinyl resin mainly composed of styrene, styrene-
Butadiene resin, silicone resin, polyurethane resin, polyamide resin, epoxy resin, polyvinyl butyral resin, rosin, modified rosin, terpene resin, phenol resin, aliphatic or alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, Paraffin wax and the like may be included.

When the toner to be used is used as a magnetic toner containing magnetic fine particles, the magnetic fine particles may be any material exhibiting magnetism or magnetizability, such as metals such as iron, manganese, nickel, cobalt and chromium, magnetite. , Hematite, various ferrites, manganese alloys, other ferromagnetic alloys, etc.
It is possible to use fine powder having a particle size of up to 5 μm. The amount of magnetic fine particles contained in the toner is 15 to 15% of the total weight of the magnetic toner.
70 wt% (more preferably 25-45 wt%) is good.

Further, various substances can be added to the core material particles used in the present invention for the purpose of coloring. Examples thereof include carbon black, iron black, graphite, nigrosine, metal complexes of monoazo dyes, ultramarine blue, phthalocyanine blue, Hansa yellow, benzine yellow, and quinacridone various lake pigments.

As a method of encapsulating these particles, a known encapsulation technique can be used. For example, spray drying method, coacervation method, phase separation method and the like can be preferably used, in-situ polymerization method, U.S. Pat.
No. 338,991, No. 3,326,848, No. 3,502,
The method described in the specification of No. 582 can also be used.

A known resin can be used as the shell material. For example, there are resins composed of the following monomers. Styrene, styrene such as P-chlorostyrene, P-dimethylamino-styrene and the like, and substituted products thereof; methyl acrylate,
Ester of acrylic acid or methacrylic acid such as ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, N, N-dimethylaminoethyl methacrylate ester; , Half amide or diester imide, vinyl pyridine, N
-Nitrogen-containing vinyl such as vinyl imidazole; vinyl acetals such as vinyl formal and vinyl butyral; vinyl monomers such as vinyl chloride, acrylonitrile, vinyl acetate; vinylidene monomers such as vinylidene chloride and vinylidene fluoride; olefin monomers such as ethylene and propylene. is there. Also, polyester, polycarbonate, polysulfonate, polyamide, polyurethane, polyurea, epoxy resin, rosin, modified rosin,
Homopolymers or copolymers of terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, aromatic petroleum resins, melamine resins, polyether resins such as polyphenylene oxide or thioether resins, or copolymers, and further Mixtures thereof can be used.

The capsulated toner of the present invention is used as a developer after optionally mixing a fluidity improver such as colloidal silica, or a lubricant, an abrasive, a charge control agent and the like.

When used as a two-component developer, it is used as a developer after being mixed with an iron powder carrier, a ferrite carrier, or a carrier coated with a silicone resin, an acrylic resin or the like.

 Next, the fixing method of the present invention will be described.

First, a schematic structure of an example of the image forming apparatus of the present invention will be described below.
Describing based on the drawings, reference numeral 1 denotes an original placing table made of a transparent member such as glass, which reciprocates in the direction of arrow a to scan the original. A short-focus small-diameter image-forming element array 2 is arranged immediately below the document placing table, and an image of the document placed on the document placing table is illuminated by an illumination lamp 3, and a reflected light image thereof is sensed by the array 2 by the photosensitive drum. 4 is slit exposed. The photosensitive drum rotates in the direction of arrow b. Reference numeral 5 denotes a charger, which uniformly charges the photosensitive drum 4 covered with, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. Drum 4 uniformly charged by this charger 5
The element array 2 forms an electrostatic image subjected to image exposure. This electrostatic latent image is visualized by the developing device 6 by using a toner made of a resin or the like which is softened and melted by heating. On the other hand, the sheets P stored in the cassette S
Is fed onto the drum 4 by a pair of conveying rollers 8 which are rotated in pressure contact with each other in the vertical direction so that the feeding roller 7 is synchronized with the image on the photosensitive drum 4.
Then, the transfer discharger 9 transfers the toner image formed on the photosensitive drum 4 onto the sheet P. After that, the sheet P separated from the drum 4 by the known separating means is guided to the fixing device 11 by the conveyance guide 10 and subjected to heat fixing processing, and then discharged onto the toilet 12. In addition,
After transferring the toner image, the residual toner on the drum 4 is cleaned.
Removed by 13.

FIG. 3 shows an enlarged view of the fixing device 11 of this embodiment. Reference numeral 20 denotes a low-heat-capacity linear heating element that is fixedly supported by the device, and as an example, an alumina substrate 21 having a thickness of 1.0 mm, a width of 10 mm, and a length of 240 mm is coated with a resistance material 22 in a width of 1.0 mm. Power is applied from both ends. Energization is a pulsed waveform with a cycle of 20 msec of DC 100 V, and is given by varying the pulse width according to the desired temperature and the amount of energy released controlled by the temperature measuring element 23. Approximate pulse width is 0.5 msec to 5 msec
Becomes When the temperature detected by the temperature measuring element 23 in the low heat capacity linear heating element 20 is T ₁ , the surface temperature T ₂ of the film 24 facing the resistance material 22 is lower than T ₁ by about 10 to 30 ° C. The film surface temperature T _{3 at} the portion where the film 24 is peeled off from the toner fixing surface is substantially equal to the temperature T ₂ .

In this way, the fixing film 24 moves in the direction of the arrow in the drawing by coming into contact with the heating body 20 whose energy and temperature are controlled. As an example of this fixing film, a heat-resistant film with a thickness of 20 μm,
For example, it is an endless film obtained by coating a release layer of polyimide, polyetherimide, PES, PFA with a conductive material added to a fluororesin such as PTFE, PAF or the like on at least the image contact surface side to a thickness of 10 μm. Generally, the total thickness is 100μ, preferably 40μ
With less than film drive, drive roller 25 and driven roller
Driven by 26 and tension, it moves in the direction of the arrow without wrinkles.

Reference numeral 27 is a pressure roller having a rubber elastic layer having a good releasability such as silicon rubber, which presses a heating body through the film at a total pressure of 4 to 20 kg to rotate in pressure contact with the film.

The unfixed toner 29 on the transfer material 28 is guided to the fixing portion by the entrance guide 30 and obtains a fixed image by the above-mentioned heating.

Although the endless belt has been described above, as shown in FIG. 3 (b), a sheet feeding shaft 31 and a winding shaft 32 may be used, and the fixing film may be an end film 24.

Image forming devices include copiers, printers and fax machines.
This is applicable to all fixing devices that form an image using toner such as.

In the heat fixing method of the present invention, the toner used has a maximum value of the endothermic peak first appearing from 40 ° C. to 120 ° C. as a result of measurement by DSC in a measuring range from 10 ° C. to 200 ° C.
A toner having a temperature of 55 ° C. is preferable, and a toner having a characteristic of 55 ° C. to 100 ° C. is particularly preferable.

Further, the temperature at the time of peeling the film from the toner fixing surface is 30 ° C. or more (more preferably 40
It is better to peel under high conditions.

The maximum value of the endothermic peak in the present invention is calculated according to ASTM D-3418-82. In particular,
10 to 15 mg of toner is sampled from room temperature to 200 ° C under a nitrogen atmosphere.
After heating at a heating rate of 10 ° C / min to 200 ° C for 10 minutes, and then rapidly cooling the toner to pretreat it in advance, then holding it again at 10 ° C for 10 minutes, then 10 ° C. / m
Measure up to 200 ℃ at a heating rate of in. In general,
The data shown in FIG. 4 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.

[Examples] Hereinafter, production examples of the polyester resin used in Examples and Comparative Examples of the present invention and production examples of toners using the resin as a binder resin will be described, but the present invention is not limited thereto. . The number of parts means parts by weight.

<Production example of polyester resin A> A total of 1500 g of the above constituent raw materials was placed in a 2-liter four-neck round bottom flask equipped with a thermometer, a stainless steel stirrer, a glass nitrogen introducing tube, and a downflow condenser. Next, the flask was placed in a mantle heater, and nitrogen gas was introduced from a glass inlet tube to keep the inside of the reactor under an inert atmosphere and heated. Thereafter, 0.10 g of dibutyltin oxide was added and the temperature was maintained at 210 ° C. to carry out a cocondensation reaction for 12 hours to obtain a polyester resin A.

The apparent viscosity η'at 50% outflow point of this polyester resin A measured by an elevated flow tester shown in Fig. 1 is
2.7 × 10 ⁴ poise and viscosity η ′ in this temperature range
The absolute value of the slope of the natural logarithm lnη ′ of
(Poise) / ° C.

<Production example of polyester resin B> A polyester B was obtained in the same manner as the polyester A except that the above constituent raw materials were used. The apparent viscosity η'at 50% outflow point of this polyester resin measured by an elevated flow tester as shown in Fig. 1 is 3.4 × 10 ³ poise, and the viscosity of the viscosity η'in this temperature range with respect to the temperature of natural logarithm lnη ' The absolute value of the slope was 0.41 n (poise) / ° C.

<Sample A> 2 parts of 100 parts of polyester resin A, 5 parts of copper phthalocyanine pigment, and 3 parts of low molecular weight polypropylene according to the above-described manufacturing example are prepared.
After melt-kneading with a shaft kneading extruder, cool, crush with an airflow crusher and classify with an air classifier to obtain an average particle size of 12
A blue core particle having a size of μm was obtained.

 The core material particles were encapsulated by the following method.

A core material particle dispersion liquid containing the above components was prepared. A 28% aqueous ammonia solution was gradually added dropwise to this dispersion until the pH of the system became alkaline, and encapsulation was performed. At this time, the temperature inside the tank was 15 ° C. and the rotation speed was 4000 rpm (auto homomixer).

 Then, it was dried over and dried to obtain a capsule toner.

Colloidal silica for 100 parts of this capsule toner
0.5 part was externally mixed and used as sample A.

Sample A on 100 parts of acrylic coated ferrite carrier
10 parts were mixed to obtain a two-component developer.

<Sample B> A sample B was obtained in the same manner as the sample A except that the polyester A was replaced with the polyester B and the low-molecular-weight polypropylene was replaced with the low-molecular-weight polyethylene.

Sample B on 100 parts of acrylic coated ferrite carrier
10 parts were mixed to obtain a two-component developer.

<Sample C> 100 parts of polyester resin B, 60 parts of magnetic material, and 3 parts of low-molecular-weight polypropylene are melt-kneaded by a twin-screw kneading extruder, cooled, crushed by an airflow crusher, and classified by an air classifier to obtain average particles. Core material particles having a diameter of 12 μm were obtained.

 The above core particles were encapsulated by the following method.

The core material particles were dispersed in a 3% aqueous solution of gelatin and stirred for 5 minutes to form gelatin grains having a film thickness of 0.8 μm. Next, this dispersion was filtered, washed with ethanol and dried to obtain an intermediate layer around the core material.
100 parts of the obtained particles were dispersed in a solution having the following composition.

This dispersion was encapsulated using a spray dryer (inlet temperature 150 ° C., outlet temperature 100 ° C., air volume 100 m / min, 2-fluid nozzle type). This obtained capsule toner 10
Sample C by externally mixing 0.6 parts of colloidal silica with 0 part
I got

Next, a fixing test was conducted using samples A to C and the heating fixing device shown in FIG. Further, a blocking property test was also conducted.

Example 1 In this fixing device, the surface temperature of the heating element is 160 ° C., the power consumption of the resistance material in the heating part is 150 W, the total pressure of the pressure roller is 7 kg, the nip between the pressure roller and the film is 3 mm, and the fixing processing speed is (Ps) set to 100 mm / sec, and as the heat-resistant sheet, a polyimide film having a thickness of 20 μm having a low-resistance release layer in which a conductive material is added to PTFE was used on the contact surface with the recording material.

At this time, the time required to reach the surface temperature of the heating body of 160 ° C. was about 1.5 sec.

Sample A was applied to an improved machine of the commercial copying machine Canon NP-6650 (manufactured by Canon Inc.) from which the fixing device was removed to obtain an unfixed image.

This unfixed image was subjected to a fixing test under the above conditions using an external fixing machine as shown in FIG.

A commercially available Canon New Dry Paper (manufactured by Canon Sales Co.) 54 g / m ₂ was used as the transfer material.

In the fixing test, a solid black portion of 20 mmφ in the obtained fixed image was rubbed with a sillbon paper applied with a load of 50 g / cm ₂ , and the image density reduction rate (%) before and after the rubbing was expressed. A Macbeth reflection densitometer was used to measure the image density. Further, the unfixed image taken out from the modified machine is continuously passed through the external fixing tester in order to check the offset resistance, and the fixing film and the opposing roller are stained, the image is removed by the offset, and the transfer material is transferred onto the image. Judgment was made by observing dirt and dirt on the back side of the transfer material.

As a result, the fixability was as good as 2 to 5% (average 2.2%) at the initial stage and after passing 200 sheets. Further, the offset resistance was such that, even after passing 10,000 unfixed images, neither stain on the transfer paper nor stain on the back side of the transfer paper was observed at all. Further, when the film of the fixing device and the surface of the facing roller were observed after continuous paper passing, almost no toner adhered.

Furthermore, when 10 g of this toner was placed in a polypropylene cc 100 cc cup in an oven with a tank temperature of 45 ° C. (constant) and left for 1 day, and the blocking property was observed, no toner soul was found. ,It was good.

Comparative Example 1 The following test was attempted in order to compare the present heat fixing device with the heating roller fixing device. An external fixing device for fixing with a heat roller was prepared. The heat roller fixing device is composed of two rolls, an upper roller and a lower roller, the surface of the upper roller is Teflon, a heater is arranged at the center thereof, and the lower roller is made of silicon rubber. Furthermore, the nip width is 3 mm. The total pressure between the rollers was 7 kg.

When a heater with power consumption of 150 w was attached to the center of the heating roller and the temperature was raised while the roll was rotating, the surface temperature finally reached 160 ° C. after 5 minutes. Therefore, the heater was changed to 900W so that the surface temperature of the fixing roller could be kept above 160 ℃. At this time, the surface temperature of the heat roller is from room temperature
The time required to reach 160 ° C was 20 seconds, and it took some time to maintain a constant temperature by controlling the temperature. In other words, the heat roll requires extremely large power consumption, and the wait time cannot be removed.

The fixing test was performed using a heat roll external fixing tester equipped with a 900 W heater, with the oil applying mechanism and the cleaning mechanism of the fixing roller being removed. The fixing processing speed was 100 mm / sec, which was the same as in Example 1.

As a result, the fixability was 2 to 7% (average 4.3%) in the density reduction rate at the initial stage and after 200 sheets, which was slightly inferior to that in Example 1. When 200 sheets were passed, the image on the image due to the offset phenomenon had already appeared. The transfer paper was seen to be missing, and the backside was smeared at 2500 sheets. Further, when the roller surface was observed after continuous paper passing, a considerable amount of toner had adhered.

Example 2 In Example 1, a fixing test was conducted by changing the fixing processing speed to 150 mm / sec. However, the surface temperature of the heating element is 170 ℃
It was set to become. At this time, the surface temperature of the heating
The time required to reach 0 ° C was about 1.5 sec. The results of the fixing test are shown in Table 1. Good results were shown as shown in Table.1.

Comparative Example 2 The external fixing tester using the hot roll used in Comparative Example 1 was used, and the fixing processing speed was 150 mm / se for comparison with Example 2.
It was changed to c and the roller surface temperature was set to 170 ° C.
At this time, the time required for the roller surface temperature to reach 170 ° C. was about 23 seconds.

The results are shown in Table.1. As shown in Table.1, the results are inferior in fixing property and offset property.

Example 3 Using toner sample B, a fixing test and a toner blocking test were performed in the same manner as in Example 1. Table 1 summarizes the test conditions and test results.

Comparative Example 3 Using toner sample B, a fixing test was conducted in the same manner as in Comparative Example 1. Test conditions and test results
It is shown in ble.1.

Example 4 Using Toner Sample C, a fixing test and a toner blocking test were performed in the same manner as in Example 1. Table 1 summarizes the test conditions and test results.

Comparative Example 4 Using toner sample C, a fixing test was conducted in the same manner as in Comparative Example 1. Test conditions and test results
It is shown in ble.1.

The endothermic temperature (T _D ) and heating body temperature (T ₁ ) by DSC, the film surface temperature (T ₂ ), and the film surface temperature at the time of peeling (T ₃ ) of the toner sample shown in the examples of the present invention are shown in Table.2. Shown in.

[Advantages of the Invention] As described above, according to the heat fixing method of the present invention, an image having good fixability can be obtained with less power consumption, no offset.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an elevated flow tester for measuring the melt viscosity of a toner or a binder resin, and FIG. 2 is an image forming apparatus equipped with a fixing device for carrying out the fixing method of the present invention. FIG. 3 (a) is a schematic sectional view of the fixing device for carrying out the fixing method of the present invention, and FIG. 3 (b) is a fixing method of another embodiment of the present invention. FIG. 3 shows a schematic cross-sectional view of a fixing device for carrying out the above. FIG. 4 is a graph showing the endothermic peak of the toner, and FIG. 5 is a graph showing the slope of the natural logarithm of the viscosity of the toner or the binder resin with respect to temperature.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical indication location G03G 13/20 15/20 101 (72) Inventor Satoshi Matsunaga 3-30-2 Shimomaruko, Ota-ku, Tokyo No. Canon Inc. (56) Reference JP-A-59-68766 (JP, A) JP-A-59-157678 (JP, A) JP-A-63-128362 (JP, A) JP-A-63-128358 (JP, A) JP 63-128359 (JP, A) JP 63-128360 (JP, A) JP 61-215558 (JP, A) JP 61-215557 (JP, A) Kai 63-58356 (JP, A)

Claims (2)

[Claims] 1. A method of heat-fixing a visible image of a toner to a recording material using a capsule toner having a core particle surface mainly composed of a binder resin, a release agent and a colorant, which is coated with a resin, the method comprising the steps of: a) The binder resin contains a polyester resin obtained by copolycondensing etherified bisphenols with a carboxylic acid having a valency of 2 or more, or an anhydride thereof or a lower alkyl ester thereof, and the polyester resin is a thermally elevated type resin. Melt viscosity η ′ measured by a flow tester is 50% at an outflow point of 10
³ to 10 ⁵ poises and the natural logarithm (ln
When η ′) is plotted against temperature, the absolute value of the slope of the graph is 1.0 ln (poise) / ° C. or less, and the capsule toner is used. , A heating member which is brought into close contact with the heating body, heat-fixes the visible image of the toner on a recording material, and a film is formed on the toner-fixing surface at a temperature higher by 30 ° C. or more than the maximum value of the endothermic peak measured by DSC of the toner. A heat fixing method, which comprises peeling. 2. A visible image of the toner is heat-fixed on a recording material by a fixedly supported heating element and a heating member that is in pressure contact with the heating element and brings the recording material into close contact with the heating element via a film. In the toner used in the heat fixing method in which the film is peeled from the toner fixing surface at a temperature of 30 ° C. or more higher than the maximum value of the endothermic peak measured by DSC of the toner, the toner is a binder resin or a release agent. A capsule toner having a core particle surface containing a colorant as a main component coated with a resin,
The binder resin contains a polyester resin obtained by copolycondensing etherified bisphenols with a carboxylic acid having a valency of 2 or more, or an anhydride thereof or a lower alkyl ester thereof, and the polyester resin is a thermally elevated type resin. Melt viscosity η ′ measured by a flow tester is 50% at an outflow point of 10
³ to 10 ⁵ poises and the natural logarithm (ln
A heat-fixing capsule toner having a characteristic that the absolute value of the slope of the graph when η ′) is plotted against temperature is 1.0 ln (poise) / ° C. or less.