JP2002006551A - Electrostatic latent image developing toner and method for fixing toner image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner, having superior fixability and hot preservation resistance, even if the toner is used for a thin fixing roller under a low surface pressure. SOLUTION: The electrostatic latent image developing toner is used in a fixing method, in which a fixing apparatus which passes a support medium with a carried toner image between two rollers is used, the thickness of a fixing roller as one of the two rollers is <=1.0 mm and <=1×105 Pa surface pressure is applied between the two rollers. The toner contains at least a bonding resin, a colorant and a wax and the melting viscosity of the bonding resin at 100 deg.C is 5×104-1×106 Pa.S.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for developing an electrostatic latent image, and more particularly to a toner for developing an electrostatic latent image used for a thin, low surface pressure fixing roller.

[0002]

2. Description of the Related Art Conventionally, various methods for electrophotography have been described in U.S. Pat. No. 2,297,691, JP-B-49-23910, and JP-B-43-24748. Uses photoconductive materials,
An electric latent image is formed on the photoreceptor by various means, then the latent image is developed using dry toner, the toner image is transferred to paper or the like, and then fixed by heating, pressing, etc., and a copy is made. What you get.

The method of developing an electric latent image is roughly classified into:
Liquid developer using a developer in which various pigments and dyes are finely dispersed in an insulating organic liquid, and colorants such as carbon black on natural or synthetic resins such as cascade method, magnetic brush method, powder cloud method, etc. There is a dry development method using a toner in which is dispersed, and the dry development method includes a one-component development method and a two-component development method using a carrier.

[0004] The method of fixing the toner image on the transfer paper by heating is roughly classified into a contact fixing method and a non-contact fixing method. The former includes heating roller fixing and belt fixing, and the latter includes flash fixing and oven (atmosphere) fixing. Can be In the heating roller fixing method, since the toner image and the heating roller are in direct contact,
It is a fixing method with extremely high thermal efficiency and can be downsized, so that it is widely used.

[0005] However, in recent years, energy saving has progressed more and more, and in some cases, the heat source is turned off during standby without fixing. In such an apparatus, the heat roller is heated immediately after the heat source is turned on, and it is necessary to reach a desired temperature in an extremely short time. For this reason, in order to enhance the thermal energy efficiency of the fixing device used in such a device, attempts have been made to reduce the thickness of the fixing roller on the side in contact with the toner image support surface to 1.0 mm or less. This makes it possible to reach a desired temperature in a very short time.

However, by setting the thickness of the fixing roller to 1.0 mm or less, the mechanical strength of the roller itself is weakened. When a large load is applied between the rollers, the roller is deformed, so that a large load cannot be applied. For this reason, the toner used in such a fixing device is required to be fixed at a low temperature that is incomparable to conventional toner.

Several proposals have been made to solve this problem. For example, Japanese Patent No. 274
Japanese Patent Application Laid-Open No. 3-122661 discloses a toner for roll fixing in which core particles composed of a polyester resin and a wax having a polar group are resin-coated and the melt viscosity of the polyester resin and the wax is specified. Japanese Unexamined Patent Publication Nos. Hei 4-85550 and Japanese Examined Patent Publication No. Hei 8-16804 disclose that a specific polyester resin and a release agent are used, and the melt viscosity of the polyester resin at 80 to 120 ° C. A film fixing toner having a specified melt viscosity of a release agent has been developed.
Japanese Patent Application Laid-Open No. 12-459 discloses a film comprising a specific polyester resin and a release agent, and defining the melt viscosity of the polyester resin at 80 to 120 ° C., the gradient of a graph of the melt viscosity and the temperature, and the melt viscosity of the specific release agent. Japanese Patent Publication No. 7-82250 discloses a fixing capsule toner containing a specific polyester resin, an organometallic compound, and a release agent,
Japanese Patent Publication No. 7-72809 discloses a toner for fixing a film in which the melt viscosity of a polyester resin at 120 to 150 ° C., the gradient of the melt viscosity and the temperature, and the melt viscosity of a specific release agent are specified. A toner composed of a styrene-acrylic resin which defines the relational expression between the melt viscosity measured at 130 ° C. and the temperature is disclosed in
No. 46989 describes a toner containing a specific charge control agent and defining an average viscosity gradient.

[0008]

However, energy saving has been progressing more and more, and when the above-mentioned thin roller and the fixing device having a low surface pressure are used, it is difficult to obtain sufficient fixing property by the conventional technology. is there. Further, in recent years, image quality has been further improved, and the particle size of the toner tends to be smaller. It is known that when the toner particle size is small, even if pressure is applied between the fixing rollers, pressure is not easily applied to the toner particles, so that the fixing property is deteriorated. Especially in the case of a fixing device with low surface pressure,
This tendency becomes remarkable.

SUMMARY OF THE INVENTION The present invention has been made in view of the above background, and even when a fixing device using a thin, low surface pressure roller is used,
An object of the present invention is to provide a toner for developing an electrostatic latent image having excellent fixability and heat-resistant storage stability, and to provide a suitable toner image fixing method using the fixing device and the toner.

[0010]

Means for Solving the Problems The present inventors have studied the above problems and arrived at the present invention. That is, according to the present invention, first, a fixing device that allows a support carrying a toner image to pass between two rollers is used, and the thickness of a fixing roller that is one of the two rollers is used. Is 1.0 mm or less, and the surface pressure applied between the two rollers is 1 × 10 ⁵ Pa
An electrostatic latent image developing toner used in a fixing method described below, wherein the toner contains at least a binder resin, a colorant, and a wax, and 100% of the binder resin.
A toner for developing an electrostatic latent image is provided, which has a melt viscosity at 5 ° C. of 5 × 10 ⁴ to 1 × 10 ⁶ Pa · S.

Second, in the toner for developing an electrostatic latent image described in the first aspect, the wax has a melt viscosity of 1 × 10
^A toner for developing an electrostatic latent image, which has a pressure of ³ to 1 × 10 ⁴ Pa · S, is provided.

Third, in the toner for developing an electrostatic latent image described in the second, the wax is contained in an amount of 0.5 to 20% by weight.
And a toner for developing an electrostatic latent image, characterized by containing Carnauba wax.

Fourthly, in the toner for developing an electrostatic latent image described in the first, second or third aspect, the weight average particle diameter of the toner is 4 to 10 μm. A developing toner is provided.

Fifth, in the toner for developing an electrostatic latent image according to the first aspect, the binder resin contains 30% by weight or more of a polyester resin. Provided.

Sixth, in the toner for developing an electrostatic latent image according to the first or fifth aspect, the binder resin contains two or more kinds of polyester resins incompatible with each other. An electrostatic latent image developing toner is provided.

Seventh, in the toner for developing an electrostatic latent image according to the first, fifth or sixth aspect, the binder resin may be one of:
There is provided a toner for developing an electrostatic latent image, characterized by containing 50% by weight of a hydrogenated petroleum resin.

Eighth, a fixing device is used in which the support carrying the toner image passes between the two rollers, and the thickness of the fixing roller, one of the two rollers, is set to 1.0 mm.
Hereinafter, the surface pressure applied between the two rollers is 1 × 10 ⁵ P
a, wherein the toner used for forming the toner image is any one of the first to seventh electrostatic latent image developing toners described above. An image fixing method is provided.

[0018]

Embodiments of the present invention will be described below. FIG. 1 shows an example of a fixing device used in the present invention.
In the figure, 1 denotes a fixing roller, and 2 denotes a pressure roller. The fixing roller 1 has a surface of a metal cylinder 3 made of a high heat conductor such as aluminum, iron, stainless steel or brass, and is provided with RTV, silicon rubber, tetrafluoroethylene-perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene ( PTF
An offset prevention layer 4 as shown in E) is coated. A heating lamp 5 is disposed inside the fixing roller 1. In many cases, the same material as the fixing roller 1 is used for the metal cylinder 6 of the pressure roller 2, and the surface of the metal cylinder 6 is PF
A, an anti-offset layer 7 such as PTFA is coated. Although not necessary, a heating lamp 8 is disposed inside the pressure roller 2.

Although not shown, the fixing roller 1 and the pressure roller 2 are pressed and rotated by springs at both ends, and rotate. The fixing support S (transfer paper such as paper) of the toner image T is passed between the fixing roller 1 and the pressure roller 2 to perform fixing.

The fixing device used in the present invention improves the temperature rise characteristics of the fixing roller by setting the thickness of the metal cylinder 3 of the fixing roller 1 to 1.0 mm or less, and the desired temperature can be reduced in a very short time. Can rise to temperature. The preferred thickness of the metal cylinder varies depending on the strength and thermal conductivity of the material used, but is preferably 0.2 to 0.1 mm.
7 mm is preferred. Further, the load (surface pressure) applied between the fixing roller and the pressure roller is preferably 1.5 × 10 ⁵ Pa or less. The surface pressure is a value obtained by dividing a load applied to both ends of the roller by a roller contact area.

The roller contact area is determined by passing a sheet, such as OHP paper, whose surface properties change greatly by heating between rollers heated to a fixing temperature, and stopping halfway through,
After holding for 0 seconds, discharge, and determine the area of the portion where the surface property has changed.

A higher roller surface pressure is advantageous for fixing a toner image. However, in a fixing device in which the thickness of the metal cylinder of the fixing roller is 1.0 mm or less, distortion of the roller is caused, so that a large load is applied. Not applied, the load is 1.5 ×
10 ⁵ Pa or less, preferably 0.5 to 1.0 × 1
0 ⁵ Pa.

The toner of the present invention comprises at least a binder resin,
Contains a colorant and a wax component as essential components, and has a melt viscosity of 5 × 10 ⁴ to 1 × 1 at 100 ° C. of the binder resin.
0 ⁶ Pa · S. The melt viscosity of the binder resin is 5 × 10 ⁴ P
In the case of a · S or less, the melt viscosity of the toner at the time of fixing is too low, and a hot offset phenomenon occurs. Conversely, if the melt viscosity of the binder resin is 1 × 10 ⁶ or more, the low-temperature fixability deteriorates.

Further, the melt viscosity of the wax at 80 ° C. is 1 × 10 ³ to 1 × 10 ⁴ Pa · S. When the melt viscosity of the wax is 1 × 10 ³ Pa · S or less, hot offset tends to occur. 1 × 10
^{If it is 4} or more, the low-temperature fixability deteriorates. The melt viscosity in the present invention is a value measured by a flow tester CFT-500C (Shimadzu Corporation), and the measurement conditions are: extrusion pressure: 1.9612 MPa, heating rate: 6 ° C./min, die diameter: 1.0 mm , Die length: Measured under the condition of 1.0 mm. The melt viscosity η is determined by the following equation.
Melt viscosity η = τ / γ = πD ⁴ P / 128LQ, where P: extrusion pressure (Pa) Q = X / 10 × A /
t D: Die diameter (mm) L: Die length (mm) t: Measurement time (s) X: Movement amount of piston with respect to measurement time t (mm) A: Cross-sectional area of piston (mm ² )

In the toner of the present invention, it is extremely important to use carnauba wax as a wax component.
Carnauba wax is a natural wax obtained from the leaves of carnauba palm, and a low-acid-type wax from which free fatty acids have been eliminated is preferred because it can be uniformly dispersed in a binder resin. The low acid value type carnauba wax from which free fatty acids have been eliminated is particularly preferable because it has a small amount of volatile components and therefore little filming on the photoreceptor and little spent on the charging member.

In the present invention, the weight-average particle size of the toner is preferably 4 to 10 μm for improving the image quality. When the thickness is 4 μm or less, not only is the productivity of the toner significantly deteriorated, but also the durability and the fluidity are deteriorated. Also 10μ
If m or more, the effect of improving the image quality cannot be expected much. A Coulter Multisizer is used for measuring the weight average particle size of the toner.

It is preferable that the toner of the present invention contains, as a resin component, 30% by weight or more of a polyester resin. A polyester resin is generally a binder resin suitable for the present invention because it can be fixed at a low temperature while maintaining heat-resistant storage stability as compared with other resins.

The polyester resin used in the present invention is:
Obtained by condensation polymerization of alcohol and carboxylic acid.
Examples of the alcohol used include glycols such as ethylene glycol, diene glycol, triethylene glycol, and propylene glycol; etherified bisphenols such as 1,4-bis (hydroxymeth) cyclohexane and bisphenol A; and other divalent alcohols. Alcohol monomers and trihydric or higher polyhydric alcohol monomers can be exemplified. Examples of the carboxylic acid include divalent organic acid monomers such as maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, and malonic acid; 1,2,4-benzyldicarboxylic acid; 1, 2,
5-benzyldicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,
Examples thereof include trivalent or higher polyvalent carboxylic acid monomers such as 3-dicarboxyl-2-methylenecarboxypropane and 1,2,7,8-octanetetracarboxylic acid.
The Tg of the polyester resin is preferably from 58 to 75C.

When the amount of the polyester resin used is 30% by weight or less, it is difficult to achieve both heat-resistant storage stability and low-temperature fixability.

It is preferable that two or more polyester resins used in the present invention are incompatible with each other. In this case, polyester resins having different properties are used as the incompatible polyester resins. By selecting each other's Tg, molecular weight, acid value, etc., polyesters A, B,
C. . . . Are incompatible with each other, exhibiting different properties from each other, and it is possible to secure a low-temperature fixing property, secure a fixing temperature range, and improve heat-resistant storage stability. When they do not become incompatible with each other, they show the average characteristics of the resins, and thus have little effect on improving the low-temperature fixing property, securing the fixing temperature range, and improving the heat-resistant storage stability.

Further, in the present invention, 1 to 5
It preferably contains 0% by weight of hydrogenated petroleum resin. Petroleum resin is a cracked oil fraction by-produced when producing ethylene acetylene, propylene, etc. by naphtha cracking,
It is obtained by refining, and is particularly preferably a petroleum resin having 5 to 8 carbon atoms, such as an aliphatic petroleum resin having ₅ to ₆ carbon atoms,
Of ₆ -C ₈ aromatic petroleum resin, aliphatic - there is an aromatic polymer type petroleum resin. The main raw materials include cyclopentadiene and higher olefinic hydrocarbons, and it is more preferable to use a petroleum resin composed of dicyclopentadiene and a C _{6 to} C ₈ aromatic hydrocarbon.

It is important that the amount of the petroleum resin in the present invention is 1 to 50% by weight based on the binder resin. When the content is 1% by weight or less, the effect of improving the fixing property is small. Also 50
If the content is more than 10% by weight, heat-resistant storage stability may be a concern.

It is more preferable to use a hydrogenated petroleum resin. Hydrogenated petroleum resins have better heat resistance storage stability than ordinary petroleum resins. As a method for hydrogenating a petroleum resin, any method may be used as long as it is a general reduction method, but a catalytic reduction method is particularly used. Specifically, using a heavy metal catalyst such as nickel, palladium or platinum, hydrogen is allowed to act directly on the petroleum resin at a high temperature and high pressure of 150 to 250 ° C. and 30 to 50 Kg / cm ² , and the unsaturated double bond of the petroleum resin This is a reduction method for adding The hydrogenation rate is determined by quantifying the unsaturated bonds of a petroleum resin that has not been replaced with hydrogen. Specifically, a hydrogenated petroleum resin is reacted with a halogen such as iodine trichloride or iodine monobromide to react with an unsaturated bond in the hydrogenated petroleum resin, and the amount of halogen absorbed by the reaction is measured. Convert the value to iodination. Then, the hydrogenation rate can be determined using a calibration curve of 0% and 100% (completely hydrogenated). Also, the softening point of the petroleum resin used (ring and ball type: JIS K6
863-1994) is preferably in the range of 90 to 140 ° C.

The toner of the present invention can use resins other than polyester resins. As the other resin used in the present invention, a conventionally known resin is used. For example, styrene, poly-α-styrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene- Maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-methyl methacrylate copolymer, styrene-
Styrene-based resins such as acrylonitrile-acrylate copolymers (homopolymers or copolymers containing styrene or styrene substituents), epoxy resins, vinyl chloride resins, rosin-modified maleic acid resins, phenolic resins, polyethylene resins, polypropylene Resins, petroleum resins, polyurethane resins, ketone resins, ethylene-ethyl acrylate copolymers, xylene resins, polyvinyl butyral resins, and the like. These resins may be used in combination with polyester resins or epoxy resins, but may be used alone. Is also possible. Also, two or more kinds may be used in combination. Also, the method for producing these resins is not particularly limited, and any of bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization can be used.

In the present invention, wax components other than carnauba wax can be used. For example, polyolefin waxes such as polypropylene wax and polyethylene wax, and natural waxes such as candelilla wax and rice wax can be used. The addition amount of the wax component is preferably 0.5 to 10 parts by weight.

In the toner of the present invention, a polarity controlling agent can be blended to control the polarity. Examples of the polarity control agent in this case include a nigrosine dye, a quaternary ammonium salt, an amino group-containing polymer, a metal-containing azo dye, a salicylic acid complex compound, and a phenol compound.

As the colorant used in the present invention, all pigments and dyes conventionally used as colorants for toner are applied. Specifically, carbon black,
There is no particular limitation on lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, calco oil blue, oil black, azo oil black, and the like. The amount of the colorant used is 1 to 10 parts by weight, preferably 3 to 7 parts by weight.

The method for producing the toner of the present invention may be a conventionally known method, in which a binder resin, a colorant, a wax component, and, if necessary, a charge control agent are mixed using a mixer or the like, and the mixture is heated, After kneading using a kneading machine such as a ruder, the mixture is cooled and solidified, and then pulverized with a pulverizer such as a jet mill, and then classified to obtain.

Other additives can be added to the toner as required. Examples of the additive include silica, aluminum oxides, and titanium oxides. When the primary purpose is to impart high fluidity, the average primary particle diameter of the hydrophobized silica or rutile type fine particle titanium oxide is preferably from 0.001 to 1 μm, preferably from 0.005 to 0.1 μm. It can be appropriately selected, and particularly, silica or titania surface-treated with an organic silane is preferable, and is usually used at a ratio of 0.1 to 5% by weight, preferably 0.2 to 2% by weight.

Further, for example, when the toner of the present invention is used as a two-component dry toner, the carrier used as a mixture may be glass, iron, ferrite, nickel, zircon, silica, or the like. 30-1000μ
m powder, or styrene-
An acrylic resin, a silicone-based resin, a polyamide-based resin, a polyvinylidene fluoride-based resin or the like can be appropriately selected and used.

[0041]

Next, the present invention will be described in more detail by way of examples. However, the present invention is not limited by the following examples. In the examples, all parts are parts by weight.

Example 1 (Toner formulation) Styrene-n-butyl acrylate copolymer (100 ° C. melt viscosity: 2.5 × 10 ⁵ ) 85 parts Carbon black (Mitsubishi Kasei Co. # 44) 10 parts Charge control agent (preservative) Tsuchiya Chemical Co., Ltd. Spiron Black TR-H) 2 parts Low molecular weight polypropylene (80 ° C melt viscosity: 2 × 10 ⁴ ) 3 parts Kneading with a biaxial extruder with the above formulation, pulverizing and classifying to obtain weight average particles. After adjusting the diameter to 10.5 μm, 0.3 parts by weight of silica fine powder (R-972: manufactured by Client Japan) was mixed using a Henschel mixer to obtain the toner of the present invention. A toner having a toner concentration of 4.0% by weight was prepared using the toner and a carrier obtained by coating spherical ferrite particles having an average particle diameter of 80 μm with a silicone resin, and the fixability and the heat-resistant storage stability were evaluated by the following evaluation methods. . The evaluation results are listed in Table 1.

◎ Evaluation method of fixing property A fixing device having the structure shown in FIG. 1 (surface pressure: 0.7 × 10 ⁵ P)
a. S) is imagio MF6550 (manufactured by Ricoh Company)
And a copying operation is performed by shaking the heater temperature to obtain a fixed image. A mending tape (manufactured by 3M) is attached to the image after fixing, and after applying a certain pressure, the film is slowly peeled off. The image density before and after that is measured by a Macbeth densitometer, and the fixing rate is calculated by the following equation. The temperature of the fixing roller is gradually lowered, and the temperature at which the fixing rate represented by the following equation becomes 80% or less is defined as the fixing temperature. Fixing ratio (%) = Image density of tape-adhered image / Image density × 100 Evaluation method of heat-resistant storage stability A 50-cc glass container is filled with toner, and left in a thermostat at 60 ° C. for 4 hours. The toner is cooled to room temperature, and the penetration is measured by a penetration test (JIS K2235-1991). The larger this value is, the better the heat-resistant storage stability is.

Comparative Example 1 (Toner formulation) Styrene-n-butyl acrylate copolymer (100 ° C. melt viscosity: 2 × 10 ⁴ ) 85 parts Carbon black (Mitsubishi Kasei Co. # 44) 10 parts Charge control agent (Hodogaya Chemical) 2 parts low molecular weight polypropylene (80 ° C. melt viscosity: 0.9 × 10 ⁴ ) 3 parts A toner was prepared according to the above-described formulation, and fixing properties were determined in the same manner as in Example 1.
The heat-resistant storage stability was evaluated. The evaluation results are listed in Table 1.

Comparative Example 2 (Preparation of Toner) Styrene-n-butyl acrylate copolymer (100 ° C. melt viscosity: 2.8 × 10 ⁶ ) 85 parts Carbon black (Mitsubishi Kasei's # 44) 10 parts Charge control agent (preservative) Tsuchiya Chemical Co., Ltd. Spiron Black TR-H) 2 parts Low molecular weight polypropylene (80 ° C melt viscosity: 2 × 10 ⁴ ) 3 parts
The heat-resistant storage stability was evaluated. The evaluation results are listed in Table 1.

Example 2 (Preparation of Toner) Styrene-n-butyl acrylate copolymer (100 ° C. melt viscosity: 2.5 × 10 ⁵ ) 84 parts Carbon black (Mitsubishi Kasei Co. # 44) 10 parts Charge control agent (preservative) Tsuchiya Chemical Co., Ltd. Spiron Black TR-H) 2 parts Low molecular weight polypropylene (80 ° C. melt viscosity: 0.5 × 10 ⁴ ) 4 parts Kneading using a biaxial extruder with the above formulation, pulverizing, classifying and weighting. After adjusting the average particle diameter to 11.5 μm, 0.3 parts by weight of silica fine powder (R-972: manufactured by Client Japan) was mixed using a Henschel mixer to obtain the toner of the present invention. This toner and a carrier obtained by coating silicone resin on spherical ferrite particles having an average particle diameter of 60 μm,
A developer having a toner concentration of 2.5% by weight was prepared, and the fixing property and the heat-resistant storage stability were evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

Example 3 (Toner formulation) Styrene-n-butyl acrylate copolymer (100 ° C. melt viscosity: 2.5 × 10 ⁵ ) 84 parts Carbon black (Mitsubishi Kasei Co. # 44) 10 parts Charge control agent (preservative) 4 parts of Carnauba wax (80 ° C melt viscosity: 6.5 × 10 ³ ) 2 parts Carnauba wax manufactured by Tsuchiya Chemical Co., Ltd. Kneading using a twin-screw extruder, pulverizing, classifying and weighting. After adjusting the average particle diameter to 10.5 μm, 0.3 parts by weight of silica fine powder (R-972: manufactured by Client Japan) was mixed using a Henschel mixer to obtain the toner of the present invention. Using this toner and a carrier in which spherical ferrite particles having an average particle diameter of 60 μm were coated with a silicone resin, a developer having a toner concentration of 4.0% by weight was adjusted, and the fixability and heat-resistant storage stability were evaluated in the same manner as in Example 1. Was. The evaluation results are listed in Table 1.

Example 4 (Toner formulation) Styrene-n-butyl acrylate copolymer (100 ° C. melt viscosity: 2.5 × 10 ⁵ ) 84 parts Carbon black (Mitsubishi Kasei Co. # 44) 10 parts Charge control agent (preservative) 4 parts of Carnauba wax (80 ° C melt viscosity: 6.5 × 10 ³ ) 2 parts Carnauba wax manufactured by Tsuchiya Chemical Co., Ltd. Kneading using a twin-screw extruder, pulverizing, classifying and weighting. After adjusting the average particle size to 5.5 μm, using a Henschel mixer, 1.0 part by weight of silica fine powder (R-972: manufactured by Client Japan) was mixed to obtain the toner of the present invention. Observation of this toner with a transmission electron microscope confirmed that the two types of polyester resins were incompatible. This toner and a carrier obtained by coating silicone resin on spherical ferrite particles having an average particle diameter of 50 μm,
A developer having a toner concentration of 6.0% by weight was prepared, and the fixing property and the heat-resistant storage stability were evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

Example 5 (Toner Formulation) 65 parts of polyester resin (weight average molecular weight 7500, Tg 57 ° C., acid value 6 mg KOH / g, 100 ° C. melt viscosity: 7.5 × 10 ⁵ ) carbon black (Mitsubishi Kasei # 44) 10 parts) Charge control agent (Spiron Black TR-H manufactured by Hodogaya Chemical Co., Ltd.) 2 parts Carnauba wax (80 ° C. melt viscosity: 6.5 × 10 ³ ) 4 parts Using a twin-screw extruder with the above formula. After kneading, pulverizing and classifying to obtain a weight average particle size of 8.5 μm, 0.5 parts by weight of silica fine powder (R-972: manufactured by Client Japan) is mixed using a Henschel mixer to prepare the toner of the present invention. Obtained. This toner and a carrier obtained by coating silicone resin on spherical ferrite particles having an average particle size of 80 μm,
A developer having a toner concentration of 3.5% by weight was prepared, and the fixing property and the heat-resistant storage stability were evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

Example 6 (Toner Formulation) 50 parts of polyester resin (weight average molecular weight 12000, Tg 59 ° C., acid value 25 mg KOH / g, 100 ° C. melt viscosity: 9.5 × 10 ⁵ ) 50 parts polyester resin (weight average molecular weight 6500, Tg 55) 35 ° C., acid viscosity 3 mg KOH / g, 100 ° C. melt viscosity: 5.5 × 10 ⁴ ) 35 parts Carbon black (Mitsubishi Kasei Co., Ltd. # 44) 10 parts Charge control agent (Hodogaya Chemical Co., Ltd. Spiron Black TR-H) 2 parts Carnauba wax (80 ° C. melt viscosity: 6.5 × 10 ³ ) 3 parts Kneading with a biaxial extruder with the above formulation, pulverizing and classifying to give a weight average particle size of 8.5 μm, then Henschel Using a mixer, 0.5 part by weight of silica fine powder (R-972: manufactured by Client Japan Co., Ltd.) was mixed to obtain the toner of the present invention. This toner and a carrier obtained by coating silicone resin on spherical ferrite particles having an average particle size of 80 μm,
A developer having a toner concentration of 3.5% by weight was prepared, and the fixing property and the heat-resistant storage stability were evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

Example 7 (Toner Formulation) 40 parts of polyester resin (weight average molecular weight 12000, Tg 59 ° C., acid value 25 mg KOH / g, 100 ° C. melt viscosity: 9.5 × 10 ⁵ ) 40 parts polyester resin (weight average molecular weight 6500, Tg 55) ° C, acid value 3 mgKOH / g, 100 ° C melt viscosity: 5.5 × 10 ⁴ ) 25 parts Resin (hydrogenation ratio 70%) 20 parts Carbon black (Mitsubishi Kasei Co. # 44) 10 parts Charge control agent (Hodogaya 2 parts Carnauba wax (80 ° C. melt viscosity: 6.5 × 10 ³ ) 3 parts Kneading with a biaxial extruder with the above formulation, pulverizing and classifying to obtain a weight average. After adjusting the particle size to 8.5 μm, 0.5 parts by weight of silica fine powder (R-972: manufactured by Client Japan Co., Ltd.) was mixed using a Henschel mixer. It was obtained over. This toner and a carrier obtained by coating silicone resin on spherical ferrite particles having an average particle size of 80 μm,
A developer having a toner concentration of 3.5% by weight was prepared, and the fixing property and the heat-resistant storage stability were evaluated in the same manner as in Example 1. The evaluation results are listed in Table 1.

[0052]

[Table 1]

From the above table, it can be seen that all of the toners of the examples in which the melt viscosity of the binder resin is within the specified range have a low fixing temperature and a high heat-resistant storage stability. If the viscosity is also within the specified range, both properties can be further improved, and if the wax is carnauba wax, it is even better.In these cases, it is preferable that the weight average particle size of the toner be within the specified range. When the resin is a polyester resin, both properties can be further improved, and when two or more polyester resins are incompatible with each other, it is better, and when a hydrogenated petroleum resin is contained, the best is obtained. It can be seen that characteristics are obtained.

[0054]

As described above, the first aspect of the present invention uses one of the two rollers using the fixing device that passes the support carrying the toner image between the two rollers. A toner for developing an electrostatic latent image used in a fixing method in which a fixing roller has a thickness of 1.0 mm or less and a surface pressure applied between the two rollers is 1 × 10 ⁵ Pa or less. Contains at least a binder resin, a colorant and a wax, and has a melt viscosity of 5
Obtained by a ^{× 10 4 ~1 × 10 6 Pa} · S, according to this arrangement, the thin, be used in the fixing device Teimen圧roller, at a low fixing temperature, and a high heat-resistant storage stability A toner can be obtained. That is, if the melt viscosity of the binder resin is lower than the above range, an offset phenomenon occurs, and if the melt viscosity is higher than the above range, the low-temperature fixability deteriorates.

According to a second aspect of the present invention, the melt viscosity of the wax of the toner is set to 1 × 10 ³ to 1 × 10 ⁴ Pa · S. According to this, both of the above characteristics can be further improved. . That is, if the melt viscosity of the wax is lower than the above range, the offset phenomenon is likely to occur, and if the melt viscosity is higher than the above range, the low-temperature fixability deteriorates.

According to the third aspect of the present invention, as the wax,
It contains 0.5 to 20% by weight of carnauba wax, and according to this, both of the above properties can be further improved. That is, Carnauba wax is suitable as the wax because the dispersion in the binder resin is uniform, and the filming on the photoreceptor and the spent on the charging member are small.

According to a fourth aspect of the present invention, the weight average particle diameter of the toner is restricted to 4 to 10 μm. If the weight average particle diameter is smaller than 4 μm, not only does productivity deteriorate, but also durability and fluidity deteriorate. If it is larger than 10 μm, the effect of improving image quality cannot be expected.

According to a fifth aspect of the present invention, 30% by weight or more of a polyester resin is contained as a binder resin of the toner. The polyester resin can be fixed at a low temperature while maintaining heat resistance storage stability. , 30% by weight or less, it is difficult to achieve both.

According to a sixth aspect of the present invention, two or more polyester resins which are incompatible with each other are contained as a binder resin of the toner. It is easy to secure the temperature range and improve heat-resistant storage stability.

According to a seventh aspect of the present invention, the binder resin of the toner contains 1 to 50% by weight of a hydrogenated petroleum resin. According to this, the effect of improving the fixing property is very good.

According to an eighth aspect of the present invention, the thickness of the fixing roller is 1.0 mm or less, and the surface pressure applied between the rollers is 1 × 10
^This is a toner image fixing method performed at a pressure of ⁵ Pa or less, wherein the toner described in any of the above sections is used. According to this method, the toner image can be fixed on the transfer paper even with the thin fixing roller and the low surface pressure due to the low fixing property and the heat-resistant storage property of the toner.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating an example of a fixing device used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3, 6 Metal cylinder 4, 7 Offset prevention layer 5, 8 Heating lamp T Toner image S Toner image adhesion support

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeru Emoto 1-3-6 Nakamagome, Ota-ku, Tokyo Stock inside Ricoh Company (72) Inventor Hideki Sugiura 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Inside Ricoh Company (72) Inventor Hiroto Higuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Inventor Tsuneshin 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company F term (reference) 2H005 AA01 AA06 CA08 CA13 CA14 EA03 EA05 EA07 FB02 2H033 AA02 BA08 BA10 BA11 BA58 BB12 BB28 BB34

Claims (8)

[Claims] 1. A fixing device for passing a support bearing a toner image between two rollers, wherein a thickness of a fixing roller as one of the two rollers is 1.0 mm or less.
An electrostatic latent image developing toner used in a fixing method in which a surface pressure applied between the two rollers is set to 1 × 10 ⁵ Pa or less, wherein the toner contains at least a binder resin, a colorant, and a wax. A toner for developing an electrostatic latent image, comprising: a binder resin having a melt viscosity at 100 ° C. of 5 × 10 ⁴ to 1 × 10 ⁶ Pa · S. 2. The toner for developing an electrostatic latent image according to claim 1, wherein the wax has a melt viscosity of 1 × 10 ³ to 1 × 1.
0 ⁴ toner for developing an electrostatic latent image, which is a Pa · S. 3. The toner for developing an electrostatic latent image according to claim 2, wherein said wax contains 0.5 to 20% by weight of carnauba wax. 4. The toner for developing an electrostatic latent image according to claim 1, wherein the toner has a weight average particle diameter of 4 to 4.
An electrostatic latent image developing toner having a thickness of 10 μm. 5. The toner for developing an electrostatic latent image according to claim 1, wherein the binder resin contains 30% by weight or more of a polyester resin. 6. The electrostatic latent image developing toner according to claim 1, wherein the binder resin contains two or more types of polyester resins that are incompatible with each other. For toner. 7. The electrostatic latent image developing toner according to claim 1, wherein the binder resin contains 1 to 50% by weight of a hydrogenated petroleum resin. Development toner. 8. A fixing device for passing a support carrying a toner image between two rollers, wherein a thickness of a fixing roller, which is one of the two rollers, is 1.0 mm or less.
8. A method for fixing a toner image, wherein the surface pressure applied between the two rollers is set to 1 × 10 ⁵ Pa or less, wherein the toner used for forming the toner image is a toner according to any one of claims 1 to 7. A toner image fixing method, which is an image developing toner.