JP2000284529A - Toner composition for flash fixing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superior toner for flash fixing capable of solving problems concerning poor fixability being a defect of the conventional flash fixing toner. SOLUTION: The flash fixing toner composition is composed essentially of at least a binder resin having a melt viscosity of 1×104-5×105 Pa.S at 100 deg.C and a colorant and a wax having a melt viscosity of 1×103-1×104 Pa.S at 80 deg.C, and it is preferable that the wax is made of a carnauba wax and a polyethylene wax and the binder resin is made of a polyester resin and an epoxy resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash fixing dry toner used for developing an electrostatic image in electrophotography and the like.

[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.

[0003] The method of developing an electric image is roughly divided 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] As a method for heat-fixing a toner image on transfer paper, there are roughly two methods: a contact fixing method and a non-contact fixing method. The former mainly uses a heat roller fixing, the latter mainly uses a flash fixing and an oven (atmosphere) fixing. I have.

The flash fixing system is a method of irradiating a toner image with a flash of, for example, xenon or a halogen flash lamp for a short period of millisecond or less, and fixing the toner image on transfer paper by radiant heat. This is a fixing method with features. (1) Since it is non-contact fixing, there is no collapse and the resolution at the time of development does not deteriorate. (2) Since the fixing time is extremely short, high-speed fixing is possible. (3) Quick start is possible because there is no waiting time for fixing. (4) Transfer paper of different thickness and paper quality can be handled.

However, the flash fixing method is non-contact, so that energy is largely dissipated to the surroundings. If the total amount of applied light energy is insufficient, the toner cannot be melted sufficiently and satisfactory fixing properties cannot be obtained. There is a problem.

As a prior art for improving the above, Japanese Patent Application Laid-Open No. 57-79957 discloses a flash fixing toner containing a crystalline compound having lubricity with a defined melting point, and Japanese Patent Publication No. 4-56869 discloses a binder. Resin surface tension at 125 ° C and 200 ° C, melt viscosity,
A flash fixing toner having a prescribed storage elastic modulus, Japanese Patent Publication No. Hei 4-22147 discloses a flash fixing toner comprising a paraffin wax and a microcrystalline wax, in which a polyester, a urethane compound, a penetration, a melting point and a density are defined. Japanese Patent Publication No. 9-258471 proposes a flash fixing toner or the like in which the melting heat of wax and the apparent viscosity of the toner at 100 ° C. and 120 ° C. are specified. However, at present, it is still difficult to obtain a flash fixing toner that shows sufficient fixing properties with a small fixing energy.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an excellent flash fixing toner which solves the drawbacks of the conventional flash fixing toner, that is, a problem relating to fixability.

[0009]

The present invention comprises at least a binder resin, a colorant and a wax component as essential components, and has a melt viscosity of 1 × 10 ⁴ at 100 ° C. of the binder resin.
A ~5 × 10 ⁵ Pa · S, a flash fixing toner composition, wherein the melt viscosity at 80 ° C. of the wax is ^{1 × 10 3 ~1 × 10 4} Pa · S is provided. The present invention also provides a flash fixing toner composition, wherein the wax component is carnauba wax.

Further, the present invention provides a toner composition for flash fixing, wherein the wax component is a polyethylene wax. Further, the present invention provides a flash fixing toner composition, wherein the binder resin is a polyester resin. Further, the present invention provides a toner composition for flash fixing, wherein the binder resin is an epoxy resin. Hereinafter, the present invention will be specifically described in detail.

In the flash fixing toner of the present invention, when the melt viscosity of the binder resin is less than 1 × 10 ⁴ Pa · S, the melt viscosity of the toner at the time of fixation is too low, resulting in “void”.
May occur. The void refers to a white spot phenomenon such as a sponge-like hole formed on the toner image at the time of flash fixing. Although the mechanism of the generation of voids is not clear, it is estimated that the voids are generated by the balance between the melt viscosity of the toner and the surface tension when the toner is melted. Conversely, if the melt viscosity of the binder resin exceeds 5 × 10 ⁵ , flash fixability deteriorates.

Further, the melt viscosity of the wax is 1 × 10 ³ P
If it is less than a · S, voids are likely to occur. 1 ×
When it exceeds 10 ⁴ , flash fixability deteriorates. The melt viscosity of the present invention is measured by a flow tester CFT-500.
C (Shimadzu Corporation), measured under the following conditions: extrusion pressure: 1.9612 MPa, heating rate: 6 ° C./mi
n, die diameter: 1.0 mm, die length: 1.0 mm, piston pressure 20.0 kgf / cm ² . 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: Amount of movement of piston with respect to measurement time t (mm) A: Cross-sectional area of piston (cm ² ) It is very 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.

Further, in the present invention, as a wax component,
It is very important to use polyethylene wax. The polyethylene wax can be used in a polymerized type, a decomposed type, a modified type, etc., but the decomposed type is most preferable. Polyethylene wax has an extremely small amount of components that evaporate during flash fixing compared to other wax components, and is therefore excellent in terms of odor.

As other wax components, polyolefin wax such as polypropylene wax and the like, and natural wax such as candelilla wax and rice wax can be used. The addition amount of the wax component is 0.5 to 1
0 parts by weight is preferred. In the present invention, it is important to use a polyester resin as the binder resin. Since the polyester resin can lower the melt viscosity without lowering the Tg as compared with other resins, it is possible to improve the fixability while maintaining the storage stability of the toner.

The polyester resin used in the present invention comprises:
Obtained by condensation polymerization of alcohol and carboxylic acid.
Examples of the alcohol used include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol;
Examples include bis (hydroxymeth) cyclohexane, etherified bisphenols such as bisphenol A, other dihydric alcohol monomers, and trihydric or higher polyhydric alcohol monomers.

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-benzenetricarboxylic acid, 1,2,5-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexane Tricarboxylic acid, 1,3-dicarboxyl-2-methylenecarboxypropane, 1,
Examples thereof include trivalent or higher polyvalent carboxylic acid monomers such as 2,7,8-octanetetracarboxylic acid. The Tg of the polyester resin is preferably from 58 to 75C. In the present invention, it is important to use an epoxy resin as the binder resin.

Since the epoxy resin can lower the melt viscosity without lowering the Tg as compared with other resins, it is possible to improve the fixability while maintaining the storage stability of the toner. Further, since epoxy resin has less odor than other resins, it is very suitable for a fixing method such as flash fixing.

The epoxy resin used in the present invention is obtained by polycondensation of bisphenol and epichlorohydrin. Examples of the bisphenol to be used include ethylene oxide, propylene oxide, butylene oxide, and an alkylene oxide adduct of a dihydric phenol, which is a reaction product of bisphenol A and bisphenol F with a mixture thereof. These bisphenols can be glycidylated with epichlorohydrin or β-methylepichlorohydrin. Especially bisphenol A
The glycidyl ether of the alkylene oxide adduct of is preferred. Further, the Tg of the epoxy resin is preferably from 58 to 75C.

In the present invention, other resins such as polyester resin and epoxy resin can be used together. As the other resin used in the present invention, a conventionally known resin is used. For example, styrene-acryl resin, vinyl chloride resin, rosin-modified maleic resin, phenol resin, polyethylene resin, polypropylene resin, petroleum resin, polyurethane resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl butyrate resin And the like. Two or more of these resins 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.

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 as long as it absorbs flash light, such as lamp black, iron black, ultramarine blue, nigrosine dye, aniline blue, calco oil blue, oil black, and azo oil black. 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 then heated, After kneading using a kneading machine such as a ruder, it is cooled and solidified, and crushed with a jet mill or the like,
After that, it can be classified.

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 size is appropriately selected from the range of 0.001 to 1 μm, preferably 0.005 to 0.1 μm as the hydrophobized silica or rutile type fine particle titanium oxide. Preferably, silica or titania treated with an organic silane is used, and usually used in a proportion 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-
Acrylic resin, silicone resin, polyamide resin,
It can be used by appropriately selecting from those coated with polyvinylidene fluoride resin or the like.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, a two-component black developer will be described as an example, but a magnetic, non-magnetic-component developer, and a monocolor developer can also be used.

Example 1 (Toner formulation) Styrene resin (melt viscosity: 3.0 × 10 ⁴ Pa · S, Tg: 65 ° C.) 85 parts by weight Carbon black (Mitsubishi Chemical # 44) 10 parts by weight Polypropylene wax (melt viscosity) : 3.0 × 10 ³ pa · S) 3 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formula using a twin-screw extruder, pulverizing, classifying and weighting. After adjusting the average particle size to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention.

A developer having a toner concentration of 3.0 parts 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 then measuring 30 mm × 30 mm using a Ricoh copier (Imagio DA505). An unfixed image was prepared. At this time, the toner adhesion amount was controlled to be 0.5 mg / cm ² .

Evaluation method for flash fixability Trapen-up TU which is a simple flash fixing device
-275 (manufactured by Riso Kagaku Kogyo Co., Ltd.) is modified, and the above-mentioned unfixed image is irradiated with flash light by a device that weakens flash light. A fixing tape (manufactured by 3M) is applied 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.

Fixing rate (%) = image density on tape / image density × 100 Comparative Example 1 (Toner formulation) Styrene resin (melt viscosity: 7.0 × 10 ⁵ Pa · S, Tg: 67 ° C.) 85 parts by weight carbon Black (Mitsubishi Kasei # 44) 10 parts by weight Polypropylene (melt viscosity: 3.0 × 10 ⁴ Pa · S) 3 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Prescription 2 After kneading using a shaft extruder, pulverizing and classifying to obtain a weight average particle size of 9.0 μm, using a Henschel mixer, 0.5 part by weight of titanium oxide fine powder was mixed. I got The same evaluation as in Example 1 was performed using this toner.

Comparative Example 2 (Toner formulation) Styrene resin (melt viscosity: 3.0 × 10 ⁴ Pa · S, Tg: 65 ° C.) 85 parts by weight Carbon black (Mitsubishi Kasei # 44) 10 parts by weight Polypropylene (melt viscosity: 3.0 × 10 ⁴ Pa · S) 3 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formula using a twin-screw extruder, pulverizing, classifying and weight-averaging. After adjusting the particle size to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain a toner of Comparative Example of the present invention. The same evaluation as in Example 1 was performed using this toner.

Comparative Example 3 (Toner formulation) Styrene resin (melt viscosity: 7.0 × 10 ⁵ Pa · S, Tg: 67 ° C.) 83 parts by weight Carbon black (Mitsubishi Chemical # 44) 10 parts by weight Polypropylene (melt viscosity: 3.0 × 10 ³ pa · S) 5 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formulation using a twin-screw extruder, pulverizing, classifying and weight-averaging. After adjusting the particle size to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain a toner of Comparative Example of the present invention. The same evaluation as in Example 1 was performed using this toner.

Example 2 (Toner formulation) Styrene resin (melt viscosity: 3.0 × 10 ⁴ Pa · S, Tg: 65 ° C.) 85 parts by weight Carbon black (Mitsubishi Kasei # 44) 10 parts by weight Carnauba wax (melt) Viscosity: 6.5 × 10 ³ pa · S) 3 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formulation using a twin-screw extruder, pulverizing and classifying. After adjusting the weight average particle diameter to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

Example 3 (Toner formulation) Styrene resin (melt viscosity: 3.0 × 10 ⁴ Pa · 8, Tg: 65 ° C.) 85 parts by weight Carbon black (Mitsubishi Chemical # 44) 10 parts by weight Polyethylene wax (melt viscosity) : 1.5 × 10 ³ pa · S) 3 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formulation using a twin-screw extruder, pulverizing, classifying and weighting. After adjusting the average particle size to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

Example 4 (Toner formulation) Polyester resin (melt viscosity: 3.0 × 10 ⁴ Pa · S, Tg: 65 ° C.) 85 parts by weight Carbon black (Mitsubishi Kasei # 44) 10 parts by weight Polypropylene wax (melt viscosity) : 3.5 × 10 ³ pa · S) 3 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formulation using a twin-screw extruder, pulverizing, classifying and weighting. After adjusting the average particle size to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

Example 5 (Toner formulation) Epoxy resin (melt viscosity: 3.5 × 10 ⁴ Pa · S, Tg: 62 ° C.) 85 parts by weight Carbon black (Mitsubishi Chemical # 44) 10 parts by weight Polypropylene wax (melt viscosity) : 3.5 × 10 ³ pa · S) 3 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formulation using a twin-screw extruder, pulverizing, classifying and weighting. After adjusting the average particle size to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

Example 6 (Toner formulation) Polyester resin (melt viscosity: 3.0 × 10 ⁴ Pa · S, Tg: 65 ° C.) 84 parts by weight Carbon black (Mitsubishi Kasei # 44) 10 parts by weight Carnauba wax (melting) Viscosity: 6.5 × 10 ³ pa · S) 4 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formula using a twin-screw extruder, pulverizing and classifying. After adjusting the weight average particle diameter to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

Example 7 (Toner formulation) Epoxy resin (melt viscosity: 3.5 × 10 ⁴ Pa · S, Tg: 62 ° C.) 84 parts by weight Carbon black (Mitsubishi Chemical # 44) 10 parts by weight Carnauba wax (melting) Viscosity: 6.5 × 10 ³ pa · S) 4 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formula using a twin-screw extruder, pulverizing and classifying. After adjusting the weight average particle diameter to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

Example 8 (Toner formulation) Polyester resin (melt viscosity: 3.0 × 10 ⁴ Pa · S, Tg: 65 ° C.) 86 parts by weight Carbon black (Mitsubishi Chemical # 44) 10 parts by weight Polyethylene wax (melt viscosity) : 2.5 × 10 ³ pa · S) 2 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with a biaxial extruder with the above formulation, pulverizing, classifying and weighting After adjusting the average particle size to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

Example 9 (Toner formulation) Epoxy resin (melt viscosity: 3.5 × 10 ⁴ Pa · S, Tg: 62 ° C.) 86 parts by weight Carbon black (Mitsubishi Kasei # 44) 10 parts by weight Polyethylene wax (melt) Viscosity: 2.5 × 10 ³ pa · S) 2 parts by weight Charge control agent (Spiron Black TR-H: Hodogaya Chemical) 2 parts by weight Kneading with the above formulation using a twin-screw extruder, pulverizing and classifying. After adjusting the weight average particle diameter to 9.0 μm, 0.5 parts by weight of titanium oxide fine powder was mixed using a Henschel mixer to obtain the toner of the present invention. Example 1 using this toner
The same evaluation was performed.

List of flash fixing property evaluation results Example 1 91.2% Comparative Example 1 55.3% Comparative Example 2 62.3% Comparative Example 3 67.1% Example 2 93.3% Example 3 95. 4% Example 4 96.7% Example 5 94.5% Example 6 98.8% Example 7 98.6% Example 8 99.8% Example 9 99.7%

[0042]

According to the present invention, it is possible to obtain a flash fixing toner having a sufficient fixing property with a small fixing energy.

Claims (5)

[Claims] 1. A binder resin containing at least a binder resin, a colorant and a wax component as essential components, the binder resin has a melt viscosity at 100 ° C. of 1 × 10 ^{4 to} 5 × 10 ⁵ Pa · S, Melt viscosity at 1 ° C is 1 × 10 ³ or more
1 × 10 ⁴ Pa · S, a toner composition for flash fixing. 2. The flash fixing toner composition according to claim 1, wherein the wax component is carnauba wax. 3. The flash fixing toner composition according to claim 1, wherein the wax component is a polyethylene wax. 4. The flash fixing toner composition according to claim 1, wherein the binder resin is a polyester resin. 5. The toner composition for flash fixing according to claim 1, wherein the binder resin is an epoxy resin.