JPH08248678A - Manufacture of magnetic toner for developing thermal fixing type magnetic latent image - Google Patents

Abstract

PURPOSE: To easily provide toner powder having stable particle size distribution at a high yield by classifying unclassified toner with bad fluidity after adding proper a fluidity regulating agent. CONSTITUTION: After external addition process, by which an external additive adheres to the surface, is carried out, classifying operation is carried out. In this classifying process, desired particle size distribution can be obtained by means of a classifying means such as an air classification device. In this process, magnetic powder is used at the rate of 200-400 parts by weight to 100 parts by weight of a binder resin. The using rate of the magnetic powder in a heat fusion type magnetic latent image developing magnetic toner ranges from 45% by weight to 70% by weight desirably, especially, the range of 50-65% by weight is preferable. When wax is contained in the heat fusion type magnetic latent image developing magnetic toner, a mold releasing property in heat roller fusion is improved, and as a result, a fusion property is improved while an offset phenomenon can be effectively prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a magnetic toner for magnetic latent image development which can be thermally fixed and which is used in a magnetic printing system.

[0002]

2. Description of the Related Art As one of the image reproducing methods which are currently put into practical use, there is a magnetic printing method to which a magnetic recording technology is applied.

In this magnetic printing system, a step of writing information on a metallic magnetic drum as a recording medium by a magnetic head to form a magnetic latent image, a step of developing the magnetic latent image with magnetic toner, a magnetic This is a system in which a visible image is obtained through a step of transferring a developed image on a drum to paper, a step of fixing the transferred image, and a step of cleaning residual toner after transfer on a magnetic drum.

The heat fixing method, which is one of the methods for fixing the developed image on the magnetic drum to the paper or the like, is a heat roll method in which the toner is pressed against the paper by passing between the heat rolls, or the heat is applied only by passing it through a heating oven. The oven method of fixing in is generally used.

However, these heat fixing methods must prevent the so-called hot offset phenomenon in which the toner is transferred to the surface of the heat roll. Therefore, it has been desired to develop a toner having a good fixing temperature characteristic and a good offset resistance.

Therefore, the fixing temperature is low, the offset resistance is sufficient, the magnetic head is not stained for a long time, and a stable and good visible image can be formed at all times.
Furthermore, it does not cause aggregation, has good heat-resistant storage stability, and has a high speed (B
As a magnetic toner for heat-fixing type magnetic latent image development capable of fixing at 4th plate 60 to 100 sheets / min), for example, JP-A-3-210 is available.
There are the ones listed in Japanese Patent No. 568.

The toner described in this publication has (a) 20 to 50 parts by weight of a binder resin containing an epoxy resin, and (b) a cubic system having a coercive force in the range of 30 to 240 Oersted or a rounded structure. 45 to 70 parts by weight of a magnetic powder containing a regular ferrosoferric oxide, (c) 1.5 to 6 parts by weight of a polyolefin wax containing a polyethylene wax or a polypropylene wax, and (d) a positive charge control agent 0.5.
A magnetic toner for developing a heat-fixing type magnetic latent image, comprising: ~ 2.5 parts by weight, wherein the triboelectric charge of the magnetic toner is -5 to +5.
The magnetic toner for heat-fixing type magnetic latent image development is in the range of μC / g.

In this publication, a fluidity-imparting agent typified by hydrophobic silica powder and carbon black powder is added as an external additive after the classification operation, which is called compounding → kneading → grinding → classification → external addition. The toner is manufactured in the manufacturing process.

[0009]

However, in the above-described method for producing a toner, the toner after the crushing step is particularly used.
Due to the affinity of the particles on the powder surface, the cohesiveness of the powder becomes high, and the fluidity becomes poor due to the formation of secondary agglomerates, etc. There was a problem that it could not be obtained stably.

An object of the present invention is to provide a toner manufacturing method which solves the above problems in the conventional manufacturing. That is, it is an object of the present invention to provide a method for producing a magnetic toner for heat-fixing type magnetic latent image development, by which a toner powder having a desired particle size distribution can be easily obtained in high yield.

[0011]

The above objects can be achieved by the present invention described below. That is, according to the present invention, a magnetic toner for developing a heat-fixing type magnetic latent image having a stable particle size distribution is obtained by adding an appropriate fluidity adjusting agent to an unclassified toner having poor fluidity and then classifying it. Is a manufacturing method for obtaining.

Next, the toner composition to which the present invention is applied will be described. The binder resin (A) used in the present invention is
Any known and commonly used resin can be used, and examples thereof include epoxy resin, styrene resin, acrylic resin, polyurethane resin, polyester resin and the like. The resin (A) preferably has a softening point in the range of 80 to 160 ° C. In the present invention, the softening point is measured by the ring and ball method and is shown as the temperature at which the resin or the like easily begins to deform.

When the softening point of the resin (A) is higher than 160 ° C., the toner transferred to the paper is not easily melted at the time of heat fixing and there is a tendency that the fixing strength cannot be increased particularly at the time of heat fixing in high speed printing. Therefore, it is not preferable. Also,
If the softening point is lower than 80 ° C., the particles tend to be fused during storage of the toner, and a so-called blocking phenomenon tends to occur, which is not preferable.

The binder resin (A) is preferably composed mainly of an epoxy resin, as will be described later. Examples of commercially available epoxy resins that can be used in the present invention include "Epiclon 3050" manufactured by Dainippon Ink and Chemicals, Inc.
(Softening point 94 to 102 ° C), "Epiclon 4050"
(Softening point 96-104 ° C), "Epiclone 7050"
(Softening point 122 to 131 ° C.), “Epicoat 1002” manufactured by Yuka Shell Epoxy Co., Ltd. (softening point 83 ° C.),
"Epicoat 1003" (softening point 89 ° C), "Epicoat 1004" (softening point 98 ° C), "Epicoat 100"
7 "(softening point 128 [deg.] C.)," Epicoat 1009 "(softening point 148 [deg.] C.)," Araldide 7072 "(softening point 75-85 [deg.] C.) manufactured by Ciba-Geigy Co., Ltd.," Araldide 7072 "(softening point 75-85). C.), “Araldite 6084” (softening point 96 to 104 ° C.), “Araldide 7097” (softening point 115 to 125 ° C.), and the like. Among them, aromatic epoxy resins such as epoxy resins obtained from bisphenol A and epihalohydrin are preferable. These binder resins may be used as a mixture of two or more, or may be used as a mixture with a small amount of another epoxy resin.

In the present invention, a small amount of polyethylene, styrene-acryl copolymer resin and polyester resin may be used in combination with the epoxy resin in order to improve the image quality and fixing property. The proportion of the epoxy resin used in the binder resin (A) used in the present invention is preferably in the range of 80 to 100% by weight.

The proportion of the binder resin (A) used in the magnetic toner for heat-fixing type magnetic latent image development of the present invention is 20 to 50.
A weight% range is preferred.

By using a binder resin containing an epoxy resin, not only is it effective in preventing dirt on the magnetic head, but a polyvinyl chloride film containing a plasticizer such as styrene or dioctyl phthalate comes into contact with a copy. When stored in the state, the phenomenon that the toner of the copy adheres to the film side and contaminates the film does not occur.

The material of the magnetic powder (B) used in the present invention is
Conventionally known materials can be used. For example, Ni, Zn, C
Ferroelectric metal powder such as ferrite Fe, Co, Ni containing metals such as u, Co, Fe, Mg and rare earth metals,
Examples thereof include metal compounds such as magnetite and γ-fematite.

However, the magnetic powder (B) used in the present invention is preferably a magnetic powder having a low coercive force (less than 300 Oersted) and a small particle size (less than 3 μm), and a coercive force of 30 to 240. It is more desirable to use cubic or rounded amorphous iron tetroxide having an Oersted range and a particle size in the range of 0.1 to 2 μm.

In the present invention, the magnetic powder (B) is 200 to 400 per 100 parts by weight of the binder resin (A).
It is used so as to be part by weight. The ratio of the magnetic powder (B) used in the magnetic toner for heat-fixing type magnetic latent image development is 45
The range is preferably from 70 to 70% by weight, particularly preferably from 50 to 65% by weight. When the amount of the magnetic powder used is less than 45% by weight, the magnetic force of the toner is weakened, the toner transportability is deteriorated, and the toner chargeability is increased, so that the dirt and fog on the magnetic head are increased. It is not preferable because it tends to occur. Further, when the usage ratio of the magnetic powder (B) is more than 70% by weight, the fixing property tends to decrease, which is not preferable.

In the case of a toner containing the magnetic powder (B), the surface is particularly apt to be rough and a small amount of the magnetic powder (B) is used.
Since the particles preferably exist on the surface and have a small surface charge and easily leak to the magnetic drum, the magnetic toner for magnetic latent image development is an insulating toner having a volume resistance in the range of 10 ¹⁰ to 10 ¹⁴ Ω · m. A magnetic toner is particularly preferable.

In the magnetic toner for developing a heat fixing type magnetic latent image,
By containing the wax (C), the releasability at the time of heat roll fixing is improved, the fixability is improved, and the offset phenomenon can be effectively prevented.

As the wax (C) of the present invention, any conventionally known wax can be used, and examples thereof include paraffin wax, polyolefin wax, silicone wax, and fluorine wax. Of these, low molecular weight polyethylene wax and polypropylene wax are preferable.

The polyethylene wax is, for example, "PE130" (softening point 12 manufactured by Hoechst Japan KK).
(0 ° C), as a paraffin wax, Hiro Kato Co., Ltd.
Examples of polypropylene waxes include "Viscole 550P" (softening point 150 ° C), "Viscole 660P" (softening point 145 ° C) and "Viscole 550P" manufactured by Sanyo Chemical Industry Co., Ltd. Haimer T
P-32 "," Hoechst Wax P "manufactured by Hoechst, West Germany
P230 "," NP-50 "of Mitsui Petrochemical Industry Co., Ltd.
5 ”and the like.

In the present invention, the wax (C) is preferably contained in the toner base material (D) in an amount of 5 to 15% by weight. Further, the proportion of the wax (C) used in the magnetic toner for heat-fixing magnetic latent image development is preferably in the range of 1.5 to 6.0% by weight.

In the production method of the present invention, each component is added as the finally obtained magnetic toner for heat-fixing type magnetic latent image developing so that the triboelectric charge amount of the magnetic toner is in the range of -5 to +5 μC / g. It is preferable to adjust.

The toner base material (D) usually contains a charge control agent in order to stably maintain a constant charge amount. A toner containing an epoxy resin as the binder resin (A) is usually -5 in a triboelectric charge measuring device.
To −40 μC / g of negative triboelectric charge.

In the magnetic latent image developing system, the magnetic toner is
The smaller the absolute value of the charge amount, the more advantageous it is to prevent the magnetic head from becoming dirty. Magnetic toner containing a negative charge control agent and epoxy resin, and magnetic toner containing a large amount of positive charge control agent have a high frictional charge amount, so they are easily charged with static electricity, and as a result, the magnetic head is easily soiled. Durability tends to deteriorate.

Therefore, when the epoxy resin is used as the binder resin (B), it is preferable to select and use the positive charge control agent and to select and use the positive charge control agent in an appropriate range with a smaller amount.

Examples of the positive charge control agent that can be used in the present invention include nigrosine dyes, triphenylmethane dyes, and quaternary ammonium salts. Examples of commercially available positive charge control agents include Orient Chemical Co., Ltd.
"Bontron N-01", "Bontron N-0"
3 "," Bontron N-04 "," Bontron N-0 "
7 ”and the like.

The proportion of the positive charge control agent used in the magnetic toner for heat-fixing type magnetic latent image development of the present invention is preferably 0.5 to 2.5% by weight. The charge amount of the magnetic toner containing the positive charge control agent in the range of 0.5 to 2.5% by weight is ± 5 μC.
Since it shows a value close to 0 μC / g from the value in the range of / g, it is possible to eliminate dirt on the magnetic head.

The toner base material (D) of the present invention contains the binder resin (A), the magnetic powder (B) and the wax (C) as essential components and, if necessary, an appropriate amount of a charge control agent. And melt-kneading. The kneading conditions are not particularly limited, but the kneading is usually carried out at the melting temperature of the resin (A) or higher until the respective components in the kneaded product become uniform. This step is usually carried out by a kneading means such as a pressure kneader or a Banbury mixer at 100 to 170 ° C. for 15 minutes to 24 hours.

An example of a suitable composition for the toner base (D) is, for example, (a) 20 to 50 parts by weight of a binder resin containing an epoxy resin, and (b) a coercive force of 30 to 2 by weight.
45-70 parts by weight of magnetic powder containing cubic iron or amorphous iron tetroxide having a roundness in the range of 40 Oersted, (c) polyolefin wax containing polyethylene wax or polypropylene wax 1.5-
Those containing 6 parts by weight and 0.5 to 2.5 parts by weight of the positive charge control agent are mentioned.

Since the homogeneously kneaded product obtained above is in the form of lumps, it is usually possible to pulverize it into powdery toner raw material (D) particles which are easy to handle. In this step, a crusher such as a jet mill or a hammer mill can be used.

Next, the powdery toner raw material (D) obtained above is mixed with an external additive (E), and the external additive (E) is added to the surface of the toner particles constituting the raw material (D). ) Is attached. The present invention has the greatest feature in this respect. That is, conventionally, the external additive (E) was attached after the toner raw material (D) was classified, whereas in the present invention, the external additive (E) is added to the toner particles of the toner raw material (D). In the method of the present invention and the conventional method, the classification step and the external additive adhesion step are reversed.

In obtaining the magnetic toner for heat-fixing type magnetic latent image development of the present invention, a known and conventional external additive (E) is used as an essential component. As the external additive (E), for the purpose of improving the fluidity of the toner, for example, a powder of hydrophobic silica powder, titanium oxide, carbon black, hydrophobic alumina oxide or the like is used, which is used on the surface of the toner particles. Attached. The amount of these external additives (E) used is preferably 5% by weight or less, particularly preferably 0.1 to 2.0% by weight, in order not to impair the fixability of the magnetic toner.

The degree of adhesion of the external additive (E) to the surface of the toner particles may be arbitrary, and the external additive (E) may be simply adhered by intermolecular force, or the surface of the particles of the external additive (E) may be adhered to the toner particles. An embedding (anchoring) process can also be performed so that a part is exposed. This adhesion process is performed, for example, by a Henschel mixer [manufactured by Mitsui Miike Coal Mine Co., Ltd.], a sheet composer [manufactured by Tokuju Co., Ltd.], a mixing / granulating / X mixer [Dalton Co., Ltd.], a mechanofusion system [Hosokawa Micron]. Co., Ltd.], a hybridization system [Nara Machinery Co., Ltd.], and the like.

The average particle diameter according to the weight distribution of the magnetic toner for heat-fixing type magnetic latent image development of the present invention is preferably in the range of 5 to 30 μm. When the average particle size is less than 5, the fixed image tends to be stained, and when the average particle size is larger than 30 μm, the resolution of the fixed image tends to decrease, which is not preferable.

In the present invention, the classification operation is carried out after the operation of adding the external additive (E) to the surface (external addition treatment). This classification operation is carried out by a classifying means such as an air classifier so as to obtain a desired particle size distribution.

According to the present invention, by performing the external addition treatment in advance before the classification, it is possible to improve the fluidity of the toner and receive the stable toner supply. As a result, a toner having a desired particle size distribution can be stably obtained, and the yield at the time of classification is also improved.

In the present invention, by adjusting so as to satisfy the above-mentioned preferable manufacturing conditions, not only the above-mentioned effects but also the low-temperature fixing property, heat-resistant storage property, high-speed printing property and magnetic head contamination prevention property are not impaired. The magnetic toner for developing a stable heat fixing type magnetic latent image can be provided while maintaining good fluidity.

[0042]

EXAMPLES The present invention will now be described in detail with reference to Examples.
First, some examples of blending of toner using various raw materials will be shown.

Formulation Example 1 100 parts by weight of "Epiclone 4050" "Heima-TB-1000" 10 parts by weight of "MAT-222" 250 parts by weight [Magnetic powder manufactured by Toda Kogyo KK] "Viscole 660P" 20 Weight part "Bontron N-01" 2 weight parts

The above components were added to a Banbury mixer at 120 ° C.
After melt-kneading by, the mixture is cooled to room temperature, pulverized by a hammer mill, and further pulverized by a jet mill. In this way, a magnetic toner that was not treated with fine powder was obtained.

<Compounding Example 2> 100 parts by weight of "Epitote 1004" 10 parts by weight of "Hima-TB-1000" [Styrene acrylic resin manufactured by Sanyo Chemical Industry Co., Ltd.] 250 parts by weight of "EPT-1000" "Sazo- Luwax H1 "20 parts by weight" Bontron N-04 "2 parts by weight

A magnetic toner of formulation example 2 was obtained by the same steps as in formulation example 1 except that the above components were used.

Next, the toner prepared in <Toner-Compounding Examples 1 and 2> is externally added. 0.2% by weight of "H-2000" [hydrophobic silica manufactured by Hoechst Japan Ltd.] and 0.2% by weight of "titanium dioxide P25" [titanium oxide manufactured by Nippon Aerosil Co., Ltd.] in each of these magnetic toners. And conductive particles (carbon black)
0.2% by weight was externally added by a device such as a Henschel mixer to obtain a toner used in the examples.

Hereinafter, all the magnetic toners used in the examples have the following particle size characteristics. D _50% average particle size; 9.5 μm 5 μm or less Fine powder content (volume%); 3.5%

The powder characteristics of the toner obtained by the classification treatment are as follows: D _50% average particle size; 10.5 ± _0.5 μ
m 5 μm or less Fine powder content (volume%); the target is to be 0.5% or less, and the toner supply is stable,
In addition, the aim was to enable high yield toner recovery.

Example 1 The following is the result of the classification treatment of the toner of <Compounding example 1> which has been subjected to the external addition treatment, using a microplex (air classifier). Table 1 shows the results of classification treatment, which was carried out 5 times, with 10 kg as one batch.

[0051]

[Table 1]

Example 2 The following Table 2 shows the results of the same classification treatment as in <Compounding Example 1> for the toner of <Compounding Example 2> that had been externally added. The classification treatment was carried out 5 times with one batch of 10 kg.

[0053]

[Table 2]

In the above-mentioned Examples 1 and 2, the toner powder fluidity was good, and from the results of each table, these toners have almost the same D _50% average particle diameter, 5 μm or less fine powder content and yield. It turns out that a stable supply can be received.
The toners of the examples were all excellent in low-temperature fixing property, heat-resistant storage property, high-speed printing property, and magnetic head contamination prevention property. The life of the toner of any of the examples was 100,000 sheets or more.

Next, in the comparative example, the same operation as in each of the above-described examples was carried out by using the toner which was not externally added, that is, the toner which was not added externally. That is, the classification of the toner of Formulation Example 1 containing no "H-2000", "P25" and the conductive particles was set as <Comparative Example 1>, and similarly, "H-2000", "P25" and the conductive particles were prepared. The classification of the toner of the blending example 2 which does not contain both of the above is set as <Comparative example 4>.

For comparison with the case of the toner after the external addition treatment used in Examples 1 and 2, the classification result when the external addition treatment is not performed is shown below. The powder characteristics of the toner used are those of the toner obtained by classification (target).
Was exactly the same as in the example.

Comparative Example 1 The following Table 3 shows the results of classification treatment of the toner of <Compounding example 1> to which no external additive was added. The classification treatment was carried out 5 times with one batch of 10 kg.

[0058]

[Table 3]

Comparative Example 2 With respect to the toner of <Compounding example 2> which has not been externally added, the results of classification treatment in the same manner as in Comparative example 1 are shown in Table 4 below. The classification treatment was carried out 5 times with one batch of 10 kg.

[0060]

[Table 4]

Example 1 (Table 1) and Comparative Example 1 (Table 3)
In comparison with Example 2 (Table 2) and Comparative Example 2 (4th)
From the results of the comparison with Table 1, if an attempt is made to obtain a toner having a desired predetermined particle size distribution, the content of fine powder having a particle size of 5 μm or less increases, and the fine powder cannot be cut well. Further, it is found that when the fine powder is cut into a predetermined amount or less, the yield is reduced and the average particle size becomes too large.

From the above results, the conventional toner was subjected to the classification treatment and then to the external addition treatment. However, by performing the external addition treatment to the toner and then the classification treatment, the toner is compared with the toner not subjected to the external addition treatment. It is possible to obtain a stable supply of toner having a desired particle size distribution. Moreover, the yield of the toner at that time was stable, and the result was high.

[0063]

According to the present invention, in order to obtain a magnetic toner for developing a heat-fixing type magnetic latent image, the order of classification treatment → external addition treatment in the conventional toner manufacturing process is changed from the order of external addition treatment → classification treatment. By doing so, the powder fluidity can be improved, and a particularly remarkable effect is obtained in that a toner powder having a predetermined particle size distribution can be stably obtained in a high yield.

Claims (4)

[Claims] 1. A binder resin (A) and a magnetic powder (B).
And a wax (C) as essential components, a toner raw material (D) is subjected to a classification operation and an external additive (E) is attached to the surface of the raw material (D) particles. A method for producing a magnetic toner for heat-fixing type magnetic latent image development, which comprises performing a classification operation after performing an operation of attaching an external additive (D) in the method of producing a magnetic toner for image development. 2. The toner base material (D) is based on 100 parts by weight of the binder resin (A), and the magnetic powder (B) is from 200 to 40.
The manufacturing method according to claim 1, wherein 0 part by weight is used. 3. A toner base material (D) contains wax (C) 5
The manufacturing method according to claim 1, wherein the content is -15% by weight. 4. The method according to claim 1, wherein the binder resin (A) is a resin containing 20% by weight or more of an epoxy resin as a main component.