JPH0750334B2 - Electrophotographic toner and manufacturing method thereof - Google Patents

Description

The present invention relates to an electrophotographic toner used for developing an electric latent image or a magnetic latent image in an electrophotographic method or an electrostatic printing method, and a method for producing the same.

Conventionally, regarding electrophotography, U.S. Pat.
As described in JP-B-42-23910 (US Pat. No. 3666363), JP-B-43-24748 (US Pat. No. 4071361), etc., the photoconductive layer is uniformly charged. Then, a light image is exposed according to the original to eliminate the electric charge in the exposed portion to form a latent image. Development is performed by adhering a fine powder electrophotographic substance, so-called toner, on the obtained electrostatic latent image. The toner is attracted to the electrostatic latent image according to the magnitude of the amount of charge on the photoconductive layer to form a toner image having a shade. If necessary, this toner image is transferred onto a supporting surface such as paper or cloth, and is permanently fixed on the supporting surface by heating, pressure, pressure heat fixing roller or the like. The toner image can also be fixed to the photoconductor layer if it is desired to omit the toner image transfer step. In addition to the fixing method described above, it is possible to use other means such as a solvent treatment or a top coating treatment.

There are many known development methods for electrophotography,
Heretofore, a cascade developing method described in U.S. Pat. No. 2618552, a magnetic brush method described in U.S. Pat. No. 2874063, and the like, which are development methods in which a toner is mixed with a carrier and used as a two-component toner, have been widely used.

However, in recent years, a developing method using a one-component magnetic toner that does not use a carrier has been used. Compared with the two-component toner described above, the developing method using the magnetic toner does not require a toner density detecting and controlling mechanism, the developing device can be easily downsized, the edge effect is small, and the solid black portion can be reproduced. It has many advantages such as being good. A so-called induced development method (for example, described in JP-B-37-491) is well known as a development method using a one-component developer. In this method, a toner having conductivity and magnetism is attached to a sleeve containing a magnet to form a magnetic brush made of toner, and the magnetic brush is brought into contact with an electrostatic latent image carrier to develop the latent image with the toner. Is. In this developing method, when the magnetic brush is opposed to the electrostatic latent image due to the toner having conductivity, a charge having a polarity opposite to that of the electrostatic latent image is induced in the toner, and thus the charge is induced. The latent image is developed based on the electric attraction between the toner and the electrostatic latent image. In such an induction developing method, as described above, the developer used is composed of only toner, and therefore the mixing ratio of them (that is, toner concentration) as in the case where this is used in combination with the carrier substance (carrier). No adjustment is required and the stirring operation for charging the developer is not particularly required, so that the entire developing device can be simply and compactly constructed. Further, there is no inconvenience such as deterioration of developed image quality due to deterioration of the carrier with time. However, there are various problems in using the conductive toner. For example, when a corona transfer method is adopted as a transfer operation to plain paper (: The corona transfer method is a method in which a transfer material is brought into contact with a toner image formed on an electrostatic latent image carrier, and corona discharge is applied from the back surface of the transfer material. When the toner is conductive, the toner particles have a charge of the same polarity as the transfer material due to a minute corona current that penetrates the plain paper that is the transfer material.
Not only is the transfer not sufficiently performed, but the toner layer as a whole has a charge of the same polarity, so that the repulsive force between the toner particles causes a problem such as a developed image protruding.

Further, JP-A-50-45639 describes a method of developing an electrostatic latent image by charging an insulating magnetic toner with a toner by a frictional charging effect with the surface of a toner supporting member. It is described that the toner image can be electrostatically transferred. However, since the insulating magnetic toner has a considerable amount of fine powder magnetic material mixed and dispersed in the toner, the chargeability of the toner is poor or unstable, and the tribo charge amount changes during use, which is always stable. It has a problem that it is difficult to obtain an image. This is mainly due to the poor mixing and uniform dispersibility of the organic binder resin and the inorganic magnetic material. From a general concept, it is considered that it is extremely difficult to make uniform when materials having completely different properties such as organic materials and inorganic materials are mixed. In particular, the magnetic substance has non-uniform activity sites on its surface, and because it has magnetic properties, it aggregates in the binder resin when dispersed in the binder resin in the required amount as a magnetic toner. Easily, the dispersibility deteriorates, and as a result, the content of the magnetic substance varies among the pulverized toner particles, which tends to result in a non-uniform toner composition, and other coloring agents added to the toner as necessary are binder resins. There is often a difference in the affinity for the magnetic substance, and when the magnetic substance is dispersed in the binder resin,
It is also caused by causing non-uniform dispersion of the colorant.

In addition, a magnetic material that is usually used in toner has a strong affinity with water, and when used in toner, uneven development in the binder resin results in deterioration of development characteristics due to the influence of adsorbed water in a high humidity environment. In many cases, deterioration in transfer characteristics causes development, which makes it unusable for practical use. Furthermore, the magnetic toner is weak in impact resistance,
There are various problems in terms of mechanical durability. Further, there is a problem that the magnetic toner has poor fluidity and is likely to aggregate.

The present invention provides an electrophotographic toner and a method for producing the same, which solve the above problems.

An object of the present invention is to provide an electrophotographic toner which has a good chargeability, and which always shows a stable chargeability during use and which produces a clear and fog-free image, and a method for producing the same.

A further object of the present invention is to provide an electrophotographic toner which exhibits good and uniform magnetism in a one-component developer which does not use a carrier and which can be electrostatically transferred, and a method for producing the same. .

Further, the object of the present invention is excellent in fluidity, does not cause aggregation,
To provide an electrophotographic toner excellent in impact resistance and a method for producing the same.

Further, it is an object of the present invention to provide an electrophotographic toner with less adhesion to the toner holding member or the surface of the photoconductor, and a method for producing the same.

Further, an object of the present invention is to provide an electrophotographic toner having a stable transfer efficiency even under a high humidity return condition and a method for producing the same.

Further, an object of the present invention is to provide a uniform electrophotographic toner having no manufacturing variations and a method for manufacturing the same.

More specifically, the present invention relates to an electrophotographic toner containing a magnetic material treated with a zirco aluminum coupling agent and a binder resin.

Further, the present invention provides a method for producing an electrophotographic toner having a kneading step, wherein the kneading step is performed in the presence of a zirco aluminum coupling agent, a magnetic material and a binder resin. To toner manufacturing method.

The zirco aluminum coupling agent used in the present invention is CAVEDON CHEMICAL in the United States.
It is sold as a zircoaluminate coupling agent CAVCO MOD, and has zirconium / aluminum as a main skeleton to which an organic ligand is bonded.

The zirco aluminum coupling agent is represented by the following formula [Al ₂ (OR ₁ O) _a A _b B _c ] _X [OC (R ₂ ) O] _Y [ZrA
_d B _e ] _Z [wherein, in the chelated aluminum portion, OR ₁ O
Represents an α, β-glycol group or an α, γ-glycol group, A represents a halogen atom, B represents a hydroxyl group,
a represents 0.05 to 2, b and c represent 0.05 to 5.
5 is shown. However, 2a + b + c is 6.

OC (R ₂ ) O in the organic ligand is (1) an alkylcarboxylic acid, an alkenylcarboxylic acid, an alkynylcarboxylic acid or an aralkylcarboxylic acid having 2 to 36 carbon atoms; (2) 2 to 18 carbons. A carboxylic acid having an amino group having atoms; (3) a dicarboxylic acid having 2 to 18 carbon atoms; (4) an acid anhydride of a dibasic acid having 2 to 18 carbon atoms; (5) 2 to A carboxylic acid having a mercapto group having 18 carbon atoms; or (6) a carboxylic acid having an epoxy group having 2 to 18 carbon atoms.

In the zirconium oxyhalogenated portion, A represents a halogen atom, B represents a hydroxyl group, and d + e represents 4.

X, Y and Z represent 1 to 100. ] Is shown.

The method for preparing the zirco aluminum coupling agent used in the present invention is described in JP-A-60-500537.

For example, the zirco-aluminum coupling agent used in Example 1 below is aluminum chlorohydrate,
2-propylene glycol is mixed to form a complex,
Then, it can be prepared by reacting with zirconium oxychloride, myristic acid and methacrylic acid.

In addition, the zirco aluminum coupling agent used in Example 2 was prepared by mixing aluminum chlorohydrate and 1,2-propylene glycol to form a complex, and then reacting with zirconium oxychloride and adipic acid. Can be prepared by

The aluminum element of the zirco aluminum coupling agent is bonded to the surface of the magnetic material through an oxo group or a hydroxyl group, and the zirconium element has an organic group and has a function of enhancing the adhesiveness or the bondability with the binder resin. There is.

The zirco aluminum coupling agent used in the present invention has a hydrogen / covalent bond force as a driving force for adsorption to the filler, like the conventional silane coupling agent, but its reactivity is far superior to that of the silane type. There is. The silane system requires heat to completely complete the adsorption reaction, and an unnecessary polymerization reaction also occurs in water. On the contrary, the zirco-aluminum system completes the reaction at room temperature within a short time. Some activators have a rapid reaction, but most of them are easily desorbed because the ionic bond is the controlling factor of the adsorptive power, and the toner using the ionic-bonding coupling agent has high moisture and high temperature and high humidity. It easily deteriorates under the environment,
There are problems such as a decrease in image density and the possibility of fogging and other adverse effects.

In the present invention, the highly reactive zirco aluminum coupling agent is used in the kneading step as described above, so that the binder resin and the magnetic substance can be uniformly and inseparably integrated. Furthermore, even when other colorants are present at the same time, the coupling agent acts during the kneading process, so that the effects on them are spillover effect, and it is uniform regardless of the type of material, organic or inorganic. Decentralization can be achieved.

More preferably, the zirco aluminum coupling agent of the present invention chemically bonds with the hydroxyl groups present on the surface of the magnetic material, and the effect of modifying the surface of the magnetic material is also obtained.

Due to this action, the magnetic material exposed on the surface of the toner can also obtain better charging characteristics and humidity characteristics.

As in the present invention, the toner to which the zirco aluminum coupling agent is added during the kneading step is compared with the toner not added or the toner treated with the silane-based or titanium-based coupling agent,
The above-mentioned object of the present invention can be sufficiently achieved, which is extremely preferable. In particular, the toner obtained by the production method of the present invention has a strong charging property due to the achievement of uniform dispersion,
It is uniform and stable, has excellent developing characteristics and transfer characteristics in a high-humidity environment, and has excellent stability of toner characteristics upon repeated use, and is optimal as a toner for electrophotography.

The content of metals such as zirconium and aluminum in the zirco aluminum coupling agent of the present invention is 0.1 to 20.0%, preferably 1.0 to 10.0%, and more preferably 2.5 to 7.0%.
Further, it is preferable that the specific gravity of the zirco aluminum coupling agent is 0.8 to 1.5 and the boiling point thereof is in the range of 50 to 80 ° C. Zirco aluminum coupling agent for 100 parts by weight of magnetic material
0.1 to 20 parts by weight, preferably 1 to 10 parts by weight may be added.

As the production method in the present invention, for example, in a mixer such as a Henschel mixer or a ball mill, raw materials such as a binder resin, a magnetic substance and a coloring agent and an appropriate amount of a zirco aluminum coupling agent are charged, and after dry mixing, melting is performed. Knead.

Alternatively, a method in which a zirco aluminum coupling agent is added at the same time when magnetic powder and a binder resin are melt-kneaded, and a magnetic powder is added by dissolving the zirco aluminum coupling agent in a solution in which the zirco aluminum coupling agent is dissolved. After removing the solvent,
Various methods such as a method of obtaining a toner powder through a kneading step are used.

The magnetic powder used in the present invention, ferromagnetic elements and alloys containing these, compounds, etc., such as magnetite, hematite, iron such as ferrite, cobalt, nickel,
There are substances conventionally known as magnetic materials such as alloys and compounds of manganese and other ferromagnetic alloys. The particle size of the magnetic powder is preferably 0.01 ~ 10μ, especially 0.03 ~
5μ is particularly preferred.

The toner used in the present invention contains a binder resin and, if necessary, an additive in addition to the magnetic powder, and examples of the binder substance include polystyrene, poly-p-chlorostyrene, polyvinyltoluene and the like. Non-crosslinked homopolymer of styrene and its substitution product; for example, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene- Methyl acrylate copolymer,
Styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate Copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer, styrene-vinyl methyl ketone copolymer, Styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer and other uncrosslinked styrene-based copolymers; silicone resin, polyvinyl chloride, polyvinyl acetate, polyethylene, polypropylene, polyester, Polyureta , Polyamide, epoxy resin, polyvinyl butyral, rosin, modified rosin, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins,
Aromatic petroleum resins, chlorinated paraffins, paraffin waxes, etc. can be used alone or in combination.

As the coloring substance used in the present invention, all known substances can be used. For example, carbon black, iron black, graphite, nigrosine, a metal complex of monoazo dye (Japanese Patent Publication No. 41-20153, 43). -17955, Gazette 43-2
No. 7596, No. 44-6397, No. 45-26478), ultramarine, phthalocyanine blue, Hansa yellow, benzidine yellow, quinacridone, various face wash such as lake pigment can be used.

To develop a latent image with the toner of the present invention, a method using a conductive magnetic toner described in U.S. Pat.No. 3,909,258, JP-A-54-42141 and JP-A-55-18656 is disclosed. There is a method of using an insulating magnetic toner described in the above, a method of using a high-resistance magnetic toner, and the like. The insulating properties described in JP-A-54-42141 and JP-A-55-18656 A method using a toner is particularly preferable.

That is, an electrostatic image carrier that holds an electrostatic image on the surface and a developer carrier that carries an insulating magnetic developer on the surface are arranged with a certain gap, and the insulating magnetic developer is used as a developer. In this method, the carrier is carried on a carrier to a thickness smaller than the gap, and the insulating magnetic developer is transferred to the electrostatic image carrier under the action of a magnetic field to develop.

Hereinafter, the method of the present invention will be specifically described based on Examples. However, this does not limit the embodiments of the present invention in any way.

[Example 1] Charge the mixture of the above composition into a Hensiel mixer,
Mixing and stirring were performed while applying high shearing force for minutes. Then, the above raw materials were melt-kneaded in a roll mill. After cooling, coarse pulverization was performed, and then fine pulverization was performed using a jet pulverizer. After that, classification was performed and 5 to 20 μm was selected to obtain a toner. This toner 10
0 parts by weight and 0.5 parts by weight of hydrophobic colloidal silica fine powder were mixed to prepare a developer. This developer was applied to a commercially available copying machine (trade name, NP-400RE, manufactured by Canon) and imaged.
A clear image without fog was obtained. Further, a durability test was conducted on 50,000 sheets, but there was almost no deterioration in copy quality. Further, the image was produced under high temperature and high humidity, but a clear image was obtained.

[Example 2] A zirco aluminum coupling agent (product number M-1) was added to a zirco aluminum coupling agent (CAVEDON CHEMICAL, product number C-
A substantially clear image was obtained when the same procedure as in Example 1 was carried out except that 1) was used.

[Example 3] 30 parts by weight of zirco aluminum coupling (CAVEDON CHEMICAL, product number C), styrene-butyl methacrylate (70: 3)
0) A toner was prepared in substantially the same manner as in Example 1 using 1000 parts by weight of the copolymer, 30 parts by weight of the nigrosine dye, 500 parts by weight of the magnetic material, and 30 parts by weight of low molecular weight polypropylene. 100 parts by weight of this toner and 0.4 parts by weight of fine silica powder were mixed to obtain a positive developer. When this developer was applied to a commercially available copying machine (trade name, NP-150Z, manufactured by Canon) having an OPC photoconductor to produce an image, a clear image free from fog was obtained. Further, a durability test of 20,000 sheets was conducted, but there was almost no deterioration in copy quality. Further, an image was produced under a high temperature and high humidity condition of 35 ° C. and 85% RH and a durability test was performed on 10,000 sheets, but a clear image was obtained.

[Example 4] Melt-kneading was performed in a roll mill except that the zirco aluminum coupling agent (product number M-1) in Example 1 was omitted. At the time when the kneaded material appears to be sufficiently melted and almost homogenized within the visual range, the above zirco aluminum coupling agent (product number M-1) is added to the melt during kneading, and kneading is continued for 10 minutes. Continued and ended. Thereafter, a magnetic toner was obtained and a durability test was conducted in the same manner as in Example 1, and the result was as good as in Example 1.

Comparative Example 1. A toner was manufactured in the same manner as in Example 3 except that the zirco aluminum coupling agent was omitted, and a durability test was performed on 10,000 sheets under high temperature and high humidity in order to see the charging characteristics.

Initially, the image density was high and the image was clear, but it was about 5000
Fogging occurs from about the number of sheets, and the image density after 10,000 sheets is remarkably lowered, causing a large amount of fogging, which is not preferable for practical use. It is considered that this is because the charge controllability of the magnetic toner deteriorated in a high humidity environment.

Comparative Example 2. Example 1 was repeated except that a titanium coupling agent was used instead of the zirco aluminum coupling agent, but about 1.
After 50,000 sheets, the image density gradually decreased and the fog tended to increase, and after 20,000 sheets, the image was inferior in sharpness.

Claims (2)

[Claims] 1. An electrophotographic toner comprising a magnetic material treated with a zirco aluminum coupling agent and a binder resin. 2. A method for producing an electrophotographic toner having a kneading step, wherein the kneading step is performed in the presence of a zirco aluminum coupling agent, a magnetic material and a binder resin. Production method.