JPH09222749A - Magnetic latent image developing toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic latent image developing toner having good imaging property, enough fixing property even for a fast printing process, good storage property without causing head contamination or changes in the image density regardless of the kinds or thickness of a recording medium. SOLUTION: This toner contains 45 to 70 pts.wt. magnetic material and 1 to 6 pts.wt. polyolefin wax containing polyethylene wax and/or polypropylene wax. The toner has such properties that the measured value T1/2 by a flow tester ranges 115 to 150 deg.C, the triboelectric charge amt. of an iron powder and the toner is controlled to -5 to 5μC/g by addition of an external additive and/or a charge controlling agent, and the electric resistance of the toner ranges 10<8> to 10<14> Ωcm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used in electrophotography, electrostatic recording, electrostatic printing, magnetic recording, etc., and more particularly to a toner for developing a magnetic latent image used in magnetic recording.

[0002]

2. Description of the Related Art A magnetic recording method is a method of writing a magnetic latent image on a magnetic drum, which is a recording medium, using a magnetic head, developing with a one-component toner containing magnetic powder, transferring, and fixing. (See JP-A-54-32328). With this method, a large number of copies can be obtained by forming a magnetic latent image once, and there is no fatigue of the photoconductor unlike the electrophotographic method, and there is no need to replace the photoconductor after every tens of thousands of copies. It has the advantage of easy maintenance.

Recently, a printer that generates less ozone has been desired due to the problem of environmental damage. In this method, however, since a process of pressing a recording medium such as paper with a resin roller from the back side is used as a transfer process, ozone is generated. There is almost no, and this is a method that has recently received a great deal of attention. The toner for developing a magnetic latent image used in this method contains a fixing resin that is fixed on the final recording paper and the like, and magnetic powder that satisfies the magnetic characteristics that enable the development of the magnetic latent image and the transportability to the development site. . Further, due to the recent demand for higher image quality, sharpness of characters has been required, and in recent years, there has been a growing demand for energy saving and high speed, and there has been a demand for a toner which is sufficiently fixed even at low temperature and has good imageability.

[0004]

The toner for developing a magnetic latent image used in the magnetic recording method requires magnetic powder to visualize the magnetic latent image. Further, for the purpose of high-speed printing, the magnetic latent image developing toner contains a resin having a relatively low softening point and a polyolefin wax.

However, the magnetic latent image developing toner disclosed in Japanese Patent Laid-Open No. 7-134439 tends to cause a phenomenon called head stain in which the toner adheres to the magnetic head when recording is continuously repeated. Further, in the process of pressing the recording medium such as paper from the back side with a resin roller or the like as the transfer process, there is a drawback that the image density largely changes depending on the type of recording medium and the paper thickness, and the sharpness of the characters changes. .

The present invention has a good magnetic property, has a sufficient fixing property even in high-speed printing, has a good storability, does not cause head stains, and does not change the image density depending on the type of recording medium or the paper thickness. To provide a toner for developing a latent image.

[0007]

[Means for Solving the Problems] We have solved the above problems, have good image quality, have sufficient fixability even at high speed printing, have good storage stability, do not cause head stains, and In order to provide a toner for developing a magnetic latent image in which the image density does not change depending on the type and the paper thickness, the inventors have made earnest studies. As a result,
The present inventors have found the following new toner and solved the above problems. That is, the present invention is a magnetic toner mainly composed of a binder resin and magnetic powder, containing 45 to 70 parts by weight of a magnetic substance and 1 to 6 parts by weight of a polyolefin wax containing a polyethylene wax and / or a polypropylene wax. The flow tester has T _{1/2 in} the range of 115 to 150 ° C., and the triboelectric charge amount of the iron powder and the toner is in the range of −5 to 5 μc / g due to the external additive and / or the charge control agent. In the range of 10 ⁸ to 10 ¹⁴ Ωcm for the magnetic latent image developing toner.

Hereinafter, the present invention will be described in detail. The magnetic recording method can be roughly classified into a magnetic latent image recording process, a developing process, a transfer process, and a fixing process, and the triboelectric charge amount of toner greatly affects the magnetic latent image recording process. In the magnetic latent image recording process, the magnetic head slightly floats above the surface of the magnetic recording medium for recording. This levitation force utilizes the viscous flow of air generated when the magnetic recording medium rotates at a high speed, and is designed to levitate only about 1 to 2 μm depending on the slider shape of the magnetic head. When toner adheres to the slider of the magnetic head, the levitation force becomes unstable, the gap between the magnetic recording medium and the magnetic head becomes uneven, and the magnetic force emitted from the magnetic head cannot be sufficiently transmitted to the magnetic recording medium.
As a result, the magnetic latent image cannot be formed.

When the phenomenon in which toner adheres to the slider of the magnetic head was investigated, it was found that the triboelectric charge amount of the toner was significantly involved, and it was found that the toner electrostatically adheres to the slider of the magnetic head. Therefore, it has been found that the magnetic latent image forming process can be stably performed if the toner is not triboelectrically charged as much as possible. The inventors of the present invention have produced and confirmed toners having various charge amounts, and found that the toner has a triboelectric charge amount of -5 to a triboelectric charge amount of iron powder.
It has been newly found that stable magnetic latent image recording can be carried out in the range of 5 μc / g.

As a method for controlling the triboelectric charge amount of the toner, there is a method using an external additive and / or a charge control agent. By adding inorganic fine particles such as hydrophobic silica, aluminum oxide, and titanium oxide, the triboelectric charge amount can be reduced to -5.
It can be controlled to ˜5 μc / g. The surface of the inorganic fine particles in this case may be treated with a coupling agent or the like. It is clear that similar results can be obtained by using a plurality of these inorganic fine particles in combination. Examples of commercially available products that can be used as external additives include “RA200H” manufactured by Nippon Aerosil Co., Ltd., “HDKH2050EP” manufactured by Wacker Chemicals East Asia Co., Ltd., and “HD”.
Hydrophobic silica such as "KH2015EP", aluminum oxide such as "RFY-C" manufactured by Nippon Aerosil Co., Ltd., and inorganic fine particles such as titanium oxide such as "T-805" manufactured by Nippon Aerosil Co., Ltd. can be used. In this way, the triboelectric charge amount with the iron powder can be controlled within the range of -5 to 5 [mu] c / g using only the external additive.

Further, depending on the charge control agent, -5 to 5 μc /
It is also possible to control to g (Japanese Patent Laid-Open No. 3-2
10568). As the charge control agent, nigrosine, a quaternary ammonium compound, a triphenylmethane dye or the like can be used. Examples of commercially available charge control agents include “Bontron N-01” manufactured by Orient Chemical Co., Ltd.,
Examples include "Bontron N-04" and "Copy Blue PR" manufactured by Hoechst Japan KK. Thus, the charge amount of the toner can be controlled by the external additive and / or the charge control agent.

Further, the electric resistance value of the toner is 10 ⁸ to 1
It is preferably in the range of 0 ¹⁴ Ωcm. When the electric resistance value of the toner is 10 ⁸ Ωcm or less, the toner easily scatters around the characters during transfer, resulting in poor image quality. Also,
When the electric resistance value of the toner is 10 ¹⁴ Ωcm or more, a discharge phenomenon easily occurs on the paper surface during transfer, and as a result, the transfer voltage cannot be increased and the image density becomes low.

This discharge phenomenon is more likely to occur as the paper thickness is thicker and the humidity is lower. As a method for controlling the electric resistance value, a conductive powder such as carbon black, conductive tin oxide or conductive titanium oxide can be added to the toner internally or externally. This is also possible by internally adding a permanent antistatic agent such as a quaternary ammonium salt group-containing copolymer to the toner (Japanese Patent Application No. 7-182765). In this way, by controlling the electric resistance value of the toner within the range of 10 ⁸ to 10 ¹⁴ Ωcm, it was possible to prevent changes in reflection density and image quality depending on the type of recording medium and paper thickness.

The magnetic powder used in the present invention is Ni, Z.
Examples thereof include metal compounds such as n, Cu, Co, Fe, Mg, ferrite Fe, magnetite, and γ-fematite.
The magnetic substance is preferably in the range of 45 to 70 parts by weight. Four
If the amount is less than 5 parts by weight, the image may be easily fogged,
If the amount is more than the amount by weight, the fixability tends to deteriorate.

The toner for magnetic latent image development of the present invention contains 1 to 6 parts by weight of a polyolefin wax containing a polyethylene wax and / or a polypropylene wax.
If it is less than 1 part by weight, the effect as a release agent is not sufficient, and if it is more than 6 parts by weight, blocking and deterioration of toner fluidity occur. Further, the polyolefin wax may be modified with a monomer. Examples of the polyethylene wax used in the present invention include "High Wax NL-500", "High Wax 320P", "High Wax NP-055", "High Wax 1120H", etc., manufactured by Mitsui Petrochemical.

As the resin used in the present invention, most of the resins generally used for electrophotography can be used, and polystyrene resin, styrene / acrylic resin copolymerized with various esters of styrene and acrylic acid or methacrylic acid,
Examples thereof include those obtained by partially crosslinking these styrene polymers, and further polyester resins, epoxy resins, polyamide resins, polyolefin resins, ethylene / vinyl acetate copolymer resins and the like.

In order to maintain a sufficient fixing property even at a high speed, T _1/2 of the toner is preferably in the range of 115 to 150 ° C. When T _1/2 is 150 ° C. or higher, the fixability becomes insufficient, and when T _1/2 is 115 ° C. or lower, offset occurs and storage stability is deteriorated. T _{1/2 of} toner is 115
The above-mentioned resins are selected and used so as to be in the range of 150 to 150 ° C., and may be used alone or in combination.

The T _1/2 of the present invention is a flow tester CFT.
The value measured under the following conditions with a -500 type (manufactured by Shimadzu Corporation) is used. 2.0 g of the toner is weighed and pressed by a molding machine with a load of 100 kg / cm ² to prepare a sample, which is measured under the following conditions. Temperature rising rate (RATE TEMP) 6.0 D / M (° C / min) Initial temperature (SET TEMP) 70.0 DEG (° C) Maximum temperature (MAX TEMP) 200.0 DEG Interval (INTERVAL) 3.0 DEG Preheat Time (PRE HEAT) 300.0 SEC (sec) Load (LOAD) 30.0 KM (kg) Capillary tube diameter (DIE (DIA)) 1.0 MM (mm) Capillary tube length (DIE (LENG)) 10. 0 MM (mm) Hereinafter, the present invention will be described in detail with reference to Examples.

[0019]

【Example】

Example 1 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High wax NL-500 20 Parts by weight (polyethylene wax manufactured by Mitsui Petrochemical Co., Ltd.) copy blue PR 6 parts by weight (charge control agent manufactured by Hoechst Industry) PRINTEX L6 15 parts by weight (carbon black manufactured by Degussa Japan) The above components were mixed, melt-kneaded, and cooled to room temperature. Then, after coarsely pulverizing and medium pulverizing, finely pulverizing and classifying with a jet mill to obtain a magnetic toner having an average particle diameter of 9 microns. [R
FY-C] (aluminum oxide manufactured by Nippon Aerosil Co., Ltd.) 0.3 parts by weight and [PRINTEX L6] (carbon black manufactured by Degussa Japan Co., Ltd.) 0.3 parts by weight were externally added and mixed to obtain the magnetic material of Example 1. Used as a latent image developing toner.
The triboelectric charge amount at this time is +3.2 μc / g,
The electric resistance was 2.1 × 10 ⁹ Ωcm and T _1/2 138 ° C.

Example 2 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL -500 20 parts by weight (polyethylene wax manufactured by Mitsui Petrochemical Co., Ltd.) Copy Blue PR 3 parts by weight (charge control agent manufactured by Hoechst Industry) The above components are mixed, melt-kneaded, cooled to room temperature, coarsely crushed and medium-crushed, and then jet milled. Were pulverized and classified to obtain a magnetic toner having an average particle size of 9 microns. [T
-805] (titanium oxide manufactured by Nippon Aerosil Co., Ltd.)
6 parts by weight and 0.5 parts by weight of [PRINTEX L6] (Carbon Black manufactured by Degussa Japan Co., Ltd.) were externally added and mixed to obtain a magnetic latent image developing toner of Example 1. At this time, the triboelectric charge amount was −2.0 μc / g, the electric resistance value was 7.2 × 10 ¹³ Ωcm, and T _1/2 125 ° C.

Example 3 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL -500 20 parts by weight (polyethylene wax manufactured by Mitsui Petrochemicals) Rheorex AS-170 10 parts by weight (Daiichi Kogyo Seiyaku Co., Ltd. (permanent antistatic agent)) Performed in the same manner as in Example 1 except that the above components were used. The toner for developing a magnetic latent image of Example 3 was used. At this time, the triboelectric charge amount was −1.2 μc / g, and the electric resistance value was 5.
It was 4 × 10 ¹¹ Ωcm and T _{1/2 was} 121 ° C.

Comparative Example 1 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL -500 20 parts by weight (polyethylene wax manufactured by Mitsui Petrochemical Co., Ltd.) Copy blue PR 6 parts by weight (charge control agent manufactured by Hoechst Industry) PRINTEX L6 20 parts by weight (carbon black manufactured by Degussa Japan) Implemented except that the above components were used. In the same manner as in Example 1, the magnetic latent image developing toner of Comparative Example 1 was obtained. At this time, the triboelectric charge amount was +2.1 μc / g, and the electric resistance value was 8.
It was 6 × 10 ⁶ Ωcm and T _1/2 142 ° C.

Comparative Example 2 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL -500 20 parts by weight (polyethylene wax manufactured by Mitsui Petrochemical Co., Ltd.) Copy Blue PR 3 parts by weight (charge control agent manufactured by Hoechst Industry) The above components are mixed, melt-kneaded, cooled to room temperature, coarsely crushed and medium-crushed, and then jet milled. Were pulverized and classified to obtain a magnetic toner having an average particle size of 9 microns. [R
FY-C] (aluminum oxide manufactured by Nippon Aerosil Co., Ltd.) (0.3 parts by weight) was externally added and mixed to obtain a magnetic latent image developing toner of Comparative Example 2. The amount of triboelectric charge at this time is +
0.6 μc / g, electric resistance value is 4.5 × 10 ¹⁴ Ω
cm, T _1/2 124 ° C.

Comparative Example 3 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL -500 20 parts by weight (polyethylene wax manufactured by Mitsui Petrochemical) Copy blue PR 6 parts by weight (Hoechst Industry charge control agent) PRINTEX L6 10 parts by weight (Degussa Japan (manufactured) carbon black) The above components are mixed, melted and kneaded at room temperature. After being cooled to a temperature, coarsely pulverized and medium pulverized, finely pulverized and classified by a jet mill to obtain a magnetic toner having an average particle diameter of 9 microns. [H
DK2050EP] (hydrophobic silica manufactured by Wacker Chemical East Asia Co., Ltd.) 0.8 part by weight and [PRINT
EX L6] (Carbon Black manufactured by Degussa Japan) was externally added and mixed to prepare a toner for developing a magnetic latent image of Comparative Example 3. The amount of triboelectric charge at this time is +
It is 6.2 μc / g and the electric resistance value is 1.6 × 10 ¹¹ Ω.
cm, T _1/2 133 ° C.

Comparative Example 4 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide, BET 7.8 m ² / g) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL-500 20 parts by weight (Mitsui Petrochemical polyethylene wax) Copy Blue PR 3 parts by weight (Hoechst Industry charge control agent) PRINTEX L6 10 parts by weight (Degussa Japan (made) carbon black) Above The components were mixed, melt-kneaded, cooled to room temperature, coarsely pulverized and medium pulverized, then finely pulverized by a jet mill and classified to obtain a magnetic toner having an average particle diameter of 9 microns. [R
974D] (hydrophobic silica manufactured by Nippon Aerosil Co., Ltd.)
0.5 parts by weight and 0.3 parts by weight of [PRINTEX L6] (Carbon Black manufactured by Degussa Japan Co., Ltd.) were externally added and mixed to obtain a magnetic latent image developing toner of Comparative Example 4. Incidentally, the frictional charge amount at this time was -8.6μc / g, the electrical resistance 9.3 × 10 ¹¹ Ωcm, was T _1/2 133 ℃.

Comparative Example 5 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide, BET 7.8 m ² / g) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL-500 30 parts by weight (Mitsui Petrochemical polyethylene wax) Copy Blue PR 3 parts by weight (Hoechst Industry charge control agent) PRINTEX L6 10 parts by weight (Degussa Japan (made) carbon black) Above A magnetic latent image developing toner of Comparative Example 5 was obtained in the same manner as in Example 2 except that the components were used. At this time, the triboelectric charge amount was −0.4 μc / g, and the electric resistance value was 3.
It was 5 × 10 ¹² Ωcm and T _1/2 129 ° C.

Comparative Example 6 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide, BET 7.8 m ² / g) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 50 parts by weight (Mitsubishi Rayon polyester resin) High wax NL-500 4 parts by weight (Mitsui Petrochemical polyethylene wax) Copy blue PR 3 parts by weight (Hoechst Industry charge control agent) PRINTEX L6 10 parts by weight (Degussa Japan (manufactured) carbon black) Above A magnetic latent image developing toner of Comparative Example 6 was obtained in the same manner as in Example 1 except that the components were used. At this time, the triboelectric charge amount was −0.9 μc / g and the electric resistance value was 8.
It was 1 × 10 ¹¹ Ωcm and T _1/2 135 ° C.

Comparative Example 7 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 140 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL-500 20 parts by weight (Mitsui Petrochemical polyethylene wax) Copy Blue PR 3 parts by weight (charge control agent manufactured by Hoechst Industry) A magnetic latent image developing toner of Comparative Example 7 was obtained in the same manner as in Example 1 except that the above components were used. At this time, the triboelectric charge amount was −3.1 μc / g and the electric resistance value was 6.
It was 8 × 10 ¹³ Ωcm and T _1/2 114 ° C.

Comparative Example 8 EPT-2000 250 parts by weight (Toda Kogyo ferrosoferric oxide) FC-051 100 parts by weight (Mitsubishi Rayon polyester resin) FC-344 60 parts by weight (Mitsubishi Rayon polyester resin) High Wax NL -500 20 parts by weight (polyethylene wax manufactured by Mitsui Petrochemical Co., Ltd.) Copy Blue PR 3 parts by weight (charge control agent manufactured by Hoechst Industry) Magnetic latent image development of Comparative Example 7 in the same manner as in Example 1 except that the above components were used. Used as toner for use. The triboelectric charge amount at this time was -3.7 μc / g, and the electric resistance value was 9.
It was 1 × 10 ¹³ Ωcm and T _1/2 154 ° C.

Next, MG-810 manufactured by Iwasaki Tsushinki Co., Ltd.
Using a 0 type printer, the image output of the magnetic toner obtained in each of the above Examples and Comparative Examples was performed. Table 1 shows the results. The evaluation method is as follows. 1) Image Density Using a Macbeth reflection densitometer RD-918 (manufactured by Sakata Shokai), a solid density of 1 cm × 1 cm was measured. 2) Triboelectric charge amount 100 parts by weight of surface iron oxide powder ([TEFV] manufactured by Powder Tech Co., Ltd.) having a particle size of 200 to 300 mesh and 3 parts by weight of each magnetic toner are mixed in a 100 ml glass container for 10 minutes, and Toshiba is mixed. It was measured with a blow-off charge amount measuring device manufactured by Chemicals. 3) Character dust ○ There is almost no toner scattering around the characters. × The toner is scattered around the characters, and the characters appear blurred. 4) Offset The state of offset when 100 sheets were continuously printed was evaluated. ○ Offset cannot be confirmed. × Offset is confirmed. 5) Storability After the magnetic toner was left in a constant temperature bath at 45 ° C. for 168 hours, the cohesion degree was measured using a powder tester manufactured by Hosokawa Micron. ○ The degree of aggregation is 10% or less. Δ The degree of aggregation is in the range of 10 to 20%. X: Aggregation degree is 20% or more. 6) Head contamination Repeat 1 recording 1 output 5000 times using each toner,
It was confirmed that toner adhered to the magnetic head and image abnormality of the output sample. 7) Fixing rate Measure the reflection density of the printed 1 cm x 1 cm solid,
Then, after sticking a cellophane tape and pressing it with a pressure of 10 kg / cm, it was peeled off at a speed of 1 cm / s and the reflection density was measured. The result was calculated by substituting it in the following formula.

[0031]

[Table 1]

As is clear from Table 1, the examples of the present invention have little difference in image density between plain paper and thick paper, no toner scattering around characters, good fog, no offset and no head stain. It can be seen that the storability is also good.

Claims (1)

[Claims] 1. A magnetic latent image developing toner mainly composed of a binder resin and magnetic powder, wherein a magnetic material is 45 to 7
0 _1/2 parts by weight, 1 to 6 parts by weight of a polyolefin wax including polyethylene wax and / or polypropylene wax, and T _1/2 measured by a flow tester
Is in the range of 115 to 150 ° C., and the triboelectric charge amount of the iron powder and the toner is −5 to −5 depending on the external additive and / or the charge control agent.
The electric resistance value of the toner is 10 ^{8 in} the range of 5 μc / g.
Toner for magnetic latent image development in the range of -10 ¹⁴ Ωcm.