JPH10161338A - Toner for developing electrostatic charge image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent offsetting and adhering around a heat roll at the time of fixation, to enable fixation at a low temp. and to suppress filming during development by allowing a releasing agent to exist in a toner in the form of a particle-shaped island component having a specified average particle diameter before heat fixation to from a sea-island structure as a phase separated structure and vanishing the phase separated structure after heat fixation. SOLUTION: Components are melted, kneaded, cooled and pulverized so that particle-shaped wax having 0.1-1μm, preferably 0.2-0.8μm average particle diameter is dispersed as an island component 1 in a toner contg. at least a bonding resin and a colorant. All of the wax is used at the time of fixation with a heat roll and little wax remains in the toner after the fixation. The wax spreads on the surface of the heat rolled and imparts releasability. It is, e.g. fatty acid ester having 70-90 deg.C m.p.

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 formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method or the like.

[0002]

2. Description of the Related Art Generally, in electrophotography, electrostatic recording, or the like, a carrier is used to develop an electrostatic latent image formed on a latent image carrier made of a photoconductive photoreceptor or a dielectric. Developed using a two-component toner mixed with a one-component toner that has been thinned by a blade or the like on a toner supply roller such as a developing sleeve, and that has been appropriately charged and finely powdered. After transferring the toner image to the transfer material, fixing by heating pressure, solvent vapor, etc.
A copy is to be obtained.

There are various toner fixing methods applied to these developing methods, but a heat roller fixing method is widely used because of its high thermal efficiency and high-speed fixing. When high-speed fixing is performed by such a heat fixing method, the toner is required to have good low-temperature fixability (or a low fixing minimum temperature). In addition, when a softening resin is contained as a binder resin, a part of the toner image adheres to the surface of the heat roller at the time of fixing, and this is transferred to copy paper to cause background contamination, so-called hot offset. This phenomenon and the so-called wrapping phenomenon (particularly when the temperature of the heat roller is low) that the copy sheet adheres to the surface of the heat roller and wraps easily occur. In particular, in the case of a color toner, these hot offset phenomena deteriorate image gloss. Further, the low softening resin causes a problem in storage stability, and may cause a blocking phenomenon during transportation or the like.

Therefore, as means for preventing these phenomena, Japanese Patent Application Laid-Open Nos. 51-143333 and 57-1488752 disclose such means.
No. 58-97056, No. 60-247250, etc., it is proposed to add various waxes such as solid silicone varnish, higher fatty acid, higher alcohol and the like as a release agent, but all of them have good low temperature. There is no known material exhibiting sufficient offset resistance and winding resistance while maintaining the fixing property. Specifically, polyolefin waxes such as conventional low-molecular-weight polyethylene and low-molecular-weight polypropylene have good offset resistance, but their low-temperature fixability is not sufficient, and vegetable waxes such as carnauba wax and candelilla wax do not have offset resistance. Properties and low-temperature fixability are good, but winding resistance is not sufficient, and solid silicone varnish, solid silicone oil, amide wax, higher fatty acid, higher alcohol and montanic acid wax have good low-temperature fixability, Insufficient offset resistance and winding resistance. In addition, conventional release materials often have so-called filming or spent in which the release agent is released from the toner and adheres to the photoreceptor or carrier during development, and it is difficult to stably form a high-quality image for a long period of time. there were.

[0005] In addition, there is another method for lowering the fixing temperature, in which the composition, thermal characteristics, molecular weight distribution and the like are specified for the purpose of imparting offset resistance and blocking property. For example, JP-A-3-139563 defines the softening temperature and the like of the toner, JP-A-3-152558 defines the molecular weight distribution, JP-A-3-145654 defines the crosslinking agent for the binder resin, and JP-A-3-206465 describes the binder resin. Made with block polymer, JP-A-3-21926
2 is specified by the viscoelastic property, and JP-A-3-188468 is specified by the acid value / hydroxyl value of the polymer.
48, 3-229264, which are defined by the acid value of the polyester, disclosed in JP-A-3-231775, 4-353866, 5-
100477 specifies the viscoelastic properties.
12, 4-23816, 4-23817, 4-5021
In 6, styrene-acrylic block copolymer is prescribed.
JP-A-4-26858, 4-81769, 4-8177
0 is defined as a block or graft copolymer of a crystalline polyester and a vinyl copolymer.
3. Japanese Patent Application Laid-Open No. 6-348058 specifies the molecular weight distribution peak, Japanese Patent Application Laid-Open No. 4-190242 specifies the molecular weight distribution and fixing method, Japanese Patent Application Laid-Open No. 4-24863 specifies the molecular weight of polyester and styrene / acrylic polymer. -264559, 4-264560, 4-27425
In 3,5-19531 and 5-18838, the molecular weight distribution is specified, in JP-A-4-277755, the molecular weight distribution is specified, and in JP-A-4-309962, an ionomer is used.

Japanese Patent Application Laid-Open No. Sho 60-31146 discloses a photo-disintegrable capsule,
2-148969 discloses an exothermic amplification material;
JP-A-81168 describes a capsule toner having a thermotropic liquid crystal polymer shell, JP-A-1-14962 describes a volume expansion of a capsule by light irradiation, and JP-A-2-251971.
In Japanese Unexamined Patent Application Publication No.
18550, a toner containing a heat-generating substance;
No. 0460, a toner containing a cyclohexane derivative, JP-A-4-291355, a toner containing a bisphenol F type epoxy resin, JP-A-4-329551, a toner containing a near-infrared light absorbing dye and an ethylenically unsaturated compound (cured by near-infrared light), JP-A-4-100475 and 4-100476 disclose a toner using a thermally decomposable resin using an azo type high molecular weight initiator, JP-A-5-173364, a toner containing a cyclohexanone ketone resin, and JP-A-8-15894 an acid value or a hydroxyl value. Using at least one polymer, a metal alkoxide was adhered to the surface of the toner, and JP-A-8-15902 showed that a chlorine-containing monomer was used as a monomer for the capsule toner, but these were insufficient.

In recent years, energy saving of OA equipment has been avoided, and it is an urgent need to improve a fixing process which occupies most of power consumption in copying machines and printers. Conventionally, energy saving in the fixing process has been studied by using the above-described technology and a resin having a low softening temperature (such as polyester). However, in the future, low-temperature fixing of toner for further energy saving will be important. For that purpose, it is not enough to use existing technologies alone, and it is necessary to develop new technologies.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a low-temperature fixing device suitable for energy-saving fixing without causing an offset phenomenon and a winding phenomenon around a heat roller at the time of fixing. Is to provide a toner having less toner.

[0009]

When a toner for developing an electrostatic latent image formed in an electrophotographic method, an electrostatic recording method, an electrostatic printing method, or the like is fixed, heat roller fixing is often performed. At that time, a release agent is used so that the toner is not offset to the heat roller. As the release agent, generally, silicone oil is applied to a heat roller, or various waxes are used as a material in the toner instead of silicone oil. The above-described silicone oil is suitable for avoiding offset properties, but in recent years, various waxes have been added to and mixed with toner to commercialize the toner in order to reduce the manufacturing cost of copying machines. However, since the addition and mixing of the wax alone does not provide sufficient releasability, an offset occurs during use, and thus a form used in combination with silicone oil has been adopted.

The present inventors have developed a toner for developing the above-mentioned electrostatic latent image, which contains a release agent component having a mean particle diameter of 0.1 μm or more and 1 μm or less before thermal fixing. Having a phase separation structure of a sea-island structure separated as an island component, but by using a toner characterized in that the phase separation structure disappears after heat fixing, without using silicone oil as a release agent. For example, the inventors have found that the above-mentioned problems can be solved even when only wax is used as a release agent, and have reached the present invention.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be specifically described based on embodiments of the present invention. In the toner containing at least the binder resin and the colorant, the average particle size as an island component is 0.1 μm or more and 1 μm or less, preferably 0.2 μm.
Each of the above components was melt-kneaded so as to be in a dispersed state of a granular wax having a particle size of 0.8 μm or less, cooled, and pulverized. The pulverized product usually has an average particle size of about 0.5 to 3 μm.

When the average particle diameter of the wax is 0.1 μm or less, offset tends to occur.
When the above is achieved, although sufficient releasability can be obtained, there has been a problem that photoreceptor filming and carrier spent occur.
If the average particle size is not more than 0.1 μm and not more than 1 μm, the wax is completely melted from the toner and does not migrate to the interface between the toner and the heat roller, and sufficient releasability cannot be obtained. When the average particle diameter is 0.1 μm or more and 1 μm or less, almost no wax remains in the toner after fixing by the heat roller, and it is found that all of the wax is used at the time of fixing. The used wax spreads over the entire surface of the heat roller, which seems to be the reason for satisfying the releasability. As the wax that causes the above phenomenon,
Preferably a fatty acid ester, more preferably a melting point of 70
Fatty acid esters having a temperature of not lower than 90 ° C and not higher than 90 ° C are exemplified. 70
If the temperature was lower than ℃, there was a problem in fluidity, and sufficient transferability could not be obtained. If the temperature exceeds 90 ° C., the fixing temperature of the toner increases, which is not preferable from the viewpoint of energy saving. Further, as shown in FIG. 2, the wax 4 does not exist in the image 2 on the surface of the toner fixed on the recording material, and only 30% of the wax 4 remains on the image surface. It was possible to obtain a releasability with no problem. In other words, by controlling the average particle size of the sea-island structure wax in the toner, and by dissolving the wax completely outside the image formed by the toner at the time of fixing, a sufficient offset property is given over time, and high image quality is obtained. Images were obtained. The fatty acid ester may be used in combination with another kind of release agent component, for example, polypropylene, polyethylene, higher alcohol and the like. However, these components are usually about 0 to 30% by weight based on the fatty acid ester.

The monomers forming the binder resin used in the present invention include styrene, o-methylstyrene,
m-methylstyrene, p-methylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, pn-
Styrenes such as nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene; ethylene, propylene, butylene , Ethylenically unsaturated monoolefins such as isobutylene, vinyl halides such as vinyl chloride, vinylidene chloride, vinyl bromide and vinyl fluoride; vinyl esters such as vinyl acetate, vinyl propionate and vinyl acetate, and methyl acrylate , Ethyl acrylate, acrylic acid-n-
Butyl, methyl methacrylate, ethyl methacrylate, trifluoroethyl acrylate, hexafluoroisopropyl acrylate, tetrafluoropropyl acrylate,
Α-methylene aliphatic monocarboxylic acid esters such as octafluoropentyl acrylate and heptadecafluorodecyl acrylate; vinyl ethers such as vinyl methyl ether; vinyl ketones such as vinyl methyl ketone;
And N-vinyl compounds such as -vinylpyrrole, N-vinylcarbazole, N-vinylindole, N-vinylpyrrolidone and the like. These monomers are
They can be used alone or in combination of two or more.

In the toner of the present invention, additives such as a coloring agent and a charge controlling agent can be used, such as carbon black, oil black, nigrosine dye, metal chelate dyes such as metal-containing dyes, and aniline dyes. , Calco oil blue, chrome yellow, ultramarine blue, methylene blue chloride, phthalocyanine blue, rose bengal, and other dyes or pigments. In the toner of the present invention, a fluidizing agent can be used,
For example, inorganic oxides such as SiO ₂ and TiO ₂ having a hydrophobic surface, inorganic fine particles such as SiC, metal soap such as zinc stearate, and the like can be used.

[0015]

EXAMPLES Examples of the present invention will be shown below, and the present invention will be described more specifically. However, the present invention is not limited to these examples.

Example 1 Binder resin Styrene-acrylic acid polymer 95 parts by weight Release agent Carnauba 5 parts by weight Coloring agent carbon black 10 parts by weight Charge control agent Salicylic acid derivative zinc salt 6 parts by weight is melt-kneaded, cooled and hammered. Coarsely crushed using a mill,
Subsequently, it was pulverized by a pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 7.3 μm.
And 1.5 parts by weight of silica fine powder was added to and mixed with 100 parts by weight of the particles to obtain a toner. 5 parts by weight of the obtained toner was mixed with 95 parts by weight of a ferrite carrier to prepare a developer, which was evaluated by FT-8200 manufactured by Ricoh. The obtained image was a high-resolution image, and no offset to the fixing roller was observed. 1000
No photoconductor filming, carrier spent, poor cleaning, and poor transfer were observed on the 00 copies.
No blocking phenomenon was observed in the heat-resistant storage test (50 ° C., 3 hours). The average particle size of the wax present in the toner was 0.4 μm as observed by a transmission electron microscope. No wax remained in the toner of the obtained image (observation result with a transmission electron microscope). 5% wax was found on the image surface. Further, wax remained on the surface of the fixing roller as a reverse image of the image.

Example 2 Binder resin Styrene-methacrylic acid-based polymer 90 parts by weight Release agent Carnauba 10 parts by weight Colorant carbon black 10 parts by weight Charge control agent Salicylic acid derivative zinc salt 5 parts by weight is melt-kneaded, cooled and hammered. Coarsely crushed using a mill,
Subsequently, it was pulverized by a pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 6.4 μm.
And 1.3 parts by weight of silica fine powder was added to and mixed with 100 parts by weight of the present particles to obtain a toner. 5 parts by weight of the obtained toner was mixed with 95 parts by weight of a ferrite carrier to prepare a developer, which was evaluated by FT-8200 manufactured by Ricoh. A high-resolution image was obtained, and no offset to the fixing roller was observed. No photoconductor filming, carrier spent, poor cleaning, and poor transfer were observed on 100,000 copies. Heat storage test (5
(0 ° C., 3 hours), no blocking phenomenon was observed. The average particle size of the wax present in the toner was 0.8 μm as observed by a transmission electron microscope. No wax remained in the toner of the obtained image (observation result with a transmission electron microscope). 3% wax was seen on the image surface. Further, wax remained on the surface of the fixing roller as a reverse image of the image.

Example 3 Binder resin Styrene-methacrylic acid polymer 60 parts by weight Fluorine polymer 10 parts by weight Ester polymer 25 parts by weight Release agent Polypropylene + carnauba 5 parts by weight Colorant carbon black 10 parts by weight Charge control 6 parts by weight of a salicylic acid derivative zinc salt are melt-kneaded, cooled and coarsely ground using a hammer mill.
Subsequently, it was pulverized by a pulverizer using an air jet method. The obtained finely pulverized product was classified to have an average particle size of 8.8 μm.
And 1.4 parts by weight of silica fine powder was added to and mixed with 100 parts by weight of the present particles to obtain a toner. 5 parts by weight of the obtained toner was mixed with 95 parts by weight of a ferrite carrier to prepare a developer, which was evaluated by FT-8200 manufactured by Ricoh. A high-resolution image was obtained, and no offset to the fixing roller was observed. No photoconductor filming, carrier spent, poor cleaning, and poor transfer were observed on 100,000 copies. Heat storage test (5
(0 ° C., 3 hours), no blocking phenomenon was observed. The average particle size of the wax present in the toner was 0.2 μm as observed by a transmission electron microscope. No wax remained in the toner of the obtained image (observation result with a transmission electron microscope). 4% wax was seen on the image surface. Further, wax remained on the surface of the fixing roller as a reverse image of the image.

Comparative Example 1 A developer was prepared in the same manner as in Example 1 except that carnauba was changed to low molecular weight polyethylene, and evaluation was performed in the same manner as in Example 1. The obtained image was an image hot-offset on the fixing roller. The average particle size of the wax present in the toner was 1.2 μm as observed by a transmission electron microscope. A large amount of wax remained in the toner of the obtained image (observation result with a transmission electron microscope).

Hereinafter, embodiments of the present invention will be described. 1. Before heat fixing, the release agent component has a sea-island structure phase-separated structure in which the average particle diameter is separated as an island component having a granular form having a particle size of 0.1 μm or more and 1 μm or less. And a toner for developing electrostatic images. 2. The toner for developing an electrostatic image according to the above item 1, wherein the toner for developing an electrostatic image contains a binder resin and a coloring agent. 3. The toner for developing an electrostatic image according to the above item 1 or 2, wherein an island component having a sea-island structure can be transferred to the entire surface of the fixing roller during thermal fixing. 4. The toner for developing an electrostatic image according to the above item 3, wherein the island component is a wax. 5. 4. The toner for developing an electrostatic image according to the item 4, wherein the wax contains at least one higher fatty acid ester. 6. 5. The toner for developing an electrostatic image according to 5 above, wherein the wax is carnauba. 7. The toner for developing an electrostatic image according to the above item 5 or 6, wherein the wax has a melting point of 70 ° C. or more and 90 ° C. or less.

8. The toner for developing an electrostatic image has an average particle size of 5 to 5.
The toner for developing an electrostatic image according to any one of the above items 1 to 7, which is 15 μm. 9. The toner for developing an electrostatic image according to any one of the above 1 to 8, wherein the release agent component is substantially absent in the image after heat fixing. 10. The toner for developing an electrostatic image as described in any one of 1 to 8 above, wherein a release agent component of 30% or less of the image surface remains on the image surface after heat fixing.

[0022]

【effect】

1. Claim 1 In particular, an electrostatic image developing toner with improved offset properties was obtained. 2. Claim 2 An improved toner for developing an electrostatic image with improved durability of the offset property is obtained. 3. Claims 3 and 4 In addition to the effects of Claims 1 and 2, a toner for developing an electrostatic image capable of fixing at a low temperature is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a toner of the present invention before heat fixing.

FIG. 2 is a schematic cross-sectional view of an image formed by the toner of the present invention.

[Explanation of symbols]

 1 wax dispersed in toner 2 image 3 paper 4 wax present on image surface

Claims (4)

[Claims] A heat-fixing release agent component has a phase separation structure of a sea-island structure in which an average particle diameter is separated as a granular island component having an average particle size of 0.1 μm or more and 1 μm or less. A toner for developing an electrostatic image, wherein the separation structure disappears. 2. The electrostatic image developing toner according to claim 1, wherein the island component having a sea-island structure is capable of transferring to the entire surface of the fixing roller during thermal fixing. 3. The toner according to claim 2, wherein the island component is a wax. 4. The toner according to claim 3, wherein the wax contains at least one higher fatty acid ester.