JPH09160290A - Toner for developing magnetic latent image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an always stable and satisfactory image well fixable even by high-speed printing, having satisfactory shelf stability and not causing the contamination of a head by using a specified toner. SOLUTION: A permanent antistatic agent contg. a copolymer having quat. ammonium salt groups is contained by 0.1-5 pts.wt. in a toner consisting essentially of a bonding resin and magnetic powder, and electrically conductive powder is added to the toner by 0.1-3 pts.wt. per 100 pts.wt. of the toner so that the electric resistance of the toner is regulated to 10<8> -10<14> Ωcm. The quantity of electric charges of the resultant toner by triboelectric charge is regulated to -5 to +5μC/g with an additive and/or an electric charge controlling agent.

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 it with a one-component toner containing magnetic powder, transferring it, and fixing it. See, for example, JP-A-54-32328). According to this method, a large number of copies can be obtained by forming a magnetic latent image at one time, and there is no photoreceptor fatigue unlike the electrophotographic method, and it is not necessary to replace the photoreceptor every tens of thousands of copies. This has the advantage that maintenance is easy.

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. Is a method that has received very little attention recently. The toner for developing a magnetic latent image used in this method contains a fixing resin to be fixed on the final recording paper and the like, and a magnetic powder satisfying magnetic properties enabling development of the magnetic latent image and transportability to a development site. .

Further, due to the recent demand for high image quality, sharpness of characters has been demanded. Further, in recent years, demand for energy saving and high speed has been increased, and a toner having good fixing property even at low temperature and having good image quality is required. It was

[0005]

Regarding the transfer process, in the process of pressing the recording medium such as paper from the back side with a resin roller or the like, the image density is largely changed depending on the type of recording medium and the thickness of the recording medium, and the sharpness of characters is reduced. It had the drawback of changing. When the transfer voltage is further increased, the change due to the type of recording medium and the paper thickness is reduced, but there is a problem that the discharge phenomenon occurs between the toner and the paper surface, the transfer voltage cannot be increased, and the reflection density is reduced as a result. It was

Therefore, it is preferable that the electric resistance value of the toner is relatively low. As a method of lowering the electrical resistance of toner,
For example, as described in Japanese Patent Application Laid-Open No. 2-7071, a method of adding a conductive substance to the toner surface has been proposed. However, in this method, a large amount of a conductive substance must be added to the toner surface, the fluidity of the toner is deteriorated, or the conductive substance is separated from the toner and transferred to the recording medium, resulting in sharpness of characters. Has the drawback that it deteriorates.

As disclosed in Japanese Patent Application Laid-Open No. 4-151166, a method of lowering electric resistance by containing carbon black uses carbon black having a large specific surface area and a large oil absorption, so that the fixing property is lowered and The sharpness of the letters was inferior. Therefore, in order to solve the above-mentioned problems, the present inventors have already filed a patent application Japanese Patent Application No. 7-1827.
As shown in No. 65, by containing a permanent antistatic agent containing a quaternary ammonium salt group-containing copolymer and reducing the electric resistance value of the resin itself, it has good imageability regardless of the type of paper, Further, it was possible to obtain a toner for developing a magnetic latent image, which has sufficient fixability even at high speed printing and does not cause head contamination.

However, there is a drawback that the image density cannot be sufficiently increased by using only the permanent antistatic agent containing the quaternary ammonium salt group-containing copolymer, depending on the case of thick paper and the environmental conditions of use. Further, the permanent antistatic agent containing the quaternary ammonium salt group-containing copolymer has a drawback that blocking easily occurs during storage.

The problem to be solved by the present invention is that it has good imageability regardless of the type of paper, has sufficient fixing property even at high speed printing, does not cause head stains, and has storage stability. To provide a good toner for developing a magnetic latent image.

[0010]

The inventors of the present invention have solved the above problems.
Solved and the image quality does not change depending on the type of paper
In addition, it has sufficient fixability even at high speed printing and is stable in storage.
The toner for magnetic latent image development that has good properties and does not cause head contamination
To provide a quaternary ammonium salt group-containing copolymer
Containing 0.1 to 5 parts by weight of a permanent antistatic agent containing
0.1 to 3 parts by weight of electroconductive powder to 100 parts by weight of toner
Externally added electric resistance value is 10⁸-10 ¹⁴In the range of Ωcm
The problem was solved by supplying a certain toner.

By adding a permanent antistatic agent containing a quaternary ammonium salt copolymer to the inside of the toner, the electric resistance of the toner base itself can be lowered. A permanent antistatic agent containing a quaternary ammonium salt copolymer whose electric resistance value was controlled was sharper in letters and had a higher fixing rate than a conductive antistatic agent having an electrically conductive substance inside the same resistance value. Is very good. It is considered that the reason for this is that in the toner prepared by containing the conductive substance, the conductive substance is desorbed from the toner base during the toner production process, and this is transferred to the recording medium at the time of transfer to cause image deterioration. Further, when the conductive substance is contained inside, the fixing property is deteriorated because the resin component is relatively insufficient.

When a conductive substance is internally added to such an extent that the sharpness of characters can be maintained, the toner itself has a high electric resistance value, and a discharge phenomenon occurs in the case of thick paper. This is the same result when the conductive substance is added only by external addition. When a conductive substance is added in this way, the reflection density is increased but the sharpness of the characters is lacking.

In the present invention, a permanent antistatic agent containing a quaternary ammonium salt group-containing copolymer is internally added to the toner to lower the electric resistance value of the toner itself, and an electrically conductive substance is externally added to the surface of the toner. Reach At this time, it is important to add the conductive substance to such an extent that the sharpness of the characters can be maintained, and the addition amount is almost the same as that containing no permanent antistatic agent containing the quaternary ammonium salt group-containing copolymer. is there. The amount of the conductive substance added varies greatly depending on the particle size of the toner and the degree of conductivity, but is preferably about 0.1 to 3 parts by weight with respect to 100 parts by weight of the toner.

The toner for developing a magnetic latent image according to the present invention will be described in more detail. The permanent antistatic agent containing a quaternary ammonium salt group-containing copolymer used in the present invention is described in, for example, JP-A-4-198308 and JP-A-6-271.
780, JP-A-6-329923 and JP-A-6-179716, including those described in
Further, it includes a quaternary ammonium salt group-containing (meth) acrylate copolymer, a quaternary ammonium salt group-containing maleimide copolymer, a quaternary ammonium salt group-containing methacrylimide copolymer, and the like. is there.

The proportion of the permanent antistatic agent containing the quaternary ammonium salt group-containing copolymer in the magnetic latent image developing toner of the present invention is preferably 0.1 to 5 parts by weight. If the proportion of the permanent antistatic agent containing the quaternary ammonium salt group-containing copolymer in the toner for magnetic latent image development is less than 0.1 parts by weight, the effect of lowering the electric resistance value decreases, resulting in a decrease in transfer voltage. It cannot be increased, and when the image is output to a recording medium such as thick paper, the reflection density is reduced. If it is more than 5 parts by weight,
There is a drawback in that storage stability is reduced.

Examples of the conductive powder that can be used include carbon black, conductive tin oxide, conductive titanium oxide, and conductive magnetic materials. Commercially available carbon black such as "Printex L6" manufactured by Degussa can be used.
For conductive tin oxide, "ELCOM T" manufactured by Catalyst Kasei Kogyo
L-30 "and the like, as conductive titanium oxide," EC-300 "manufactured by Titanium Industry," FT-1000 "manufactured by Ishihara Sangyo, etc.,
Also, as the conductive magnetic material, "RB-BL" manufactured by Titanium Industry Co., Ltd.
Etc. can be used.

The proportion of the conductive powder externally added to the magnetic latent image developing toner of the present invention is 0.1 to 3 parts by weight, preferably 0.1 to 1 part by weight, relative to 100 parts by weight of the toner. The ratio of conductive carbon black added externally is
If it is less than 0.1 part by weight, the effect of lowering the electric resistance value is reduced, and if it is more than 3 parts by weight, the sharpness of the characters becomes poor. Further, the fluidity of the toner is deteriorated, which is not preferable.

As the resin used in the present invention, most of the resins generally used for electrophotography can be used. Polystyrene resin, styrene / acrylic resin copolymerized with various esters of styrene and acrylic acid or methacrylic acid,
Further, those obtained by partially crosslinking these styrene-based polymers, and further polyester resins, epoxy resins, polyamide resins, polyolefin resins, ethylene / vinyl acetate copolymer resins and the like can be used. These resins can be used alone or as a mixture of several kinds. These resins are selected and used according to the fixing method, and 20 to 20 are used for the toner for magnetic latent image development.
Used in the range of 60 parts by weight.

The magnetic powder used in the present invention includes Ni,
Examples include metal compounds such as Zn, Cu, Co, Fe, Mg, ferrite Fe, magnetite, and γ-fematite. The ratio of the magnetic powder in the toner for developing a magnetic latent image of the present invention is preferably 50 to 70 parts by weight. If the ratio of the magnetic powder is less than 50 parts by weight, the magnetic force of the toner becomes weak, the toner transportability is deteriorated, and the fog tends to increase, which is not preferable. On the other hand, if the amount is more than 70 parts by weight, the fixing property is deteriorated, which is not preferable.

Further, since the magnetic head slightly floats on the surface of the magnetic recording medium for recording, when the frictional charge of the toner is large, the toner adheres to the magnetic head and the floating becomes unstable, and the magnetic recording medium becomes unstable. The distance between the magnetic head and the magnetic head becomes uneven, and the image quality deteriorates. In order to solve this problem, the triboelectric charge amount of the magnetic latent image developing toner is -5.
5 μC / g is preferred. As a method for controlling this, there is a method using an external additive and / or a charge control agent. By adding hydrophobic silica, aluminum oxide, or titanium oxide, the triboelectric charge amount can be controlled to -5 to 5 µC / g. In addition, it is clear that the same result can be obtained by using a plurality of external additives in this case.

Commercial products usable as external additives include
“RA200H” manufactured by Nippon Aerosil Co., Ltd. and “HDKH2050” manufactured by Wacker Chemicals East Asia Co., Ltd.
EP "," HDKH2015EP "and the like can be used, and aluminum oxide" RFY "manufactured by Nippon Aerosil Co., Ltd. can be used.
-C "and the like, and as titanium oxide," T-805 "manufactured by Nippon Aerosil Co., Ltd. and the like can be used. Thus, the external additive alone can be controlled to -5 to 5 [mu] C / g.

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
(See JP 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-0” manufactured by Orient Chemical Co., Ltd.
1 ”,“ Bontron N-04 ”,“ Copy Blue PR ”manufactured by Hoechst Japan KK, and the like. Thus, the charge amount of the toner can be controlled by the external additive and / or the charge control agent. In the present invention, a wax may be contained to improve offset and fixability. As the wax that can be used in the present invention, a polyolefin wax such as polyethylene wax or polypropylene wax can be used. As the polyethylene wax, "High Wax NL-50" manufactured by Mitsui Petrochemical Industry Co., Ltd.
0 "(softening point 110 ° C) and the like can be used, and as the polypropylene wax," High Wax NP055 "(softening point 136 ° C) manufactured by Mitsui Petrochemical Co., Ltd. and the like can be used.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described with reference to Examples, but these Examples show embodiments of the present invention and are not limited thereto without departing from the scope of the present invention. is not.

[0024]

【Example】

Example 1 KBF-100S 250 parts by weight (Kanto Denka Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) Rolex AS-170 3 parts by weight (a quaternary ammonium salt group-containing copolymer manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) High wax NL-500 10 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 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. T-805 1 part by weight (titanium oxide manufactured by Nippon Aerosil) Printex L6 0.3 part by weight (conductive carbon black manufactured by Degussa) This magnetic toner 1
The toner for magnetic latent image development of Example 1 was obtained by externally mixing and mixing the above components with 00 parts by weight. At this time, the triboelectric charge amount was −2.0 μC / g and the electric resistance value was 2.3 × 10 ¹³ Ωcm.

Comparative Example 1 A magnetic latent image developing toner of Comparative Example 1 was prepared in the same manner as in Example 1 except that Printex L6 was not added and mixed. At this time, the triboelectric charge amount was −2.8 μC / g and the electric resistance value was 7.8 × 10 ¹³ Ωcm.

Example 2 KBF-100S 250 parts by weight (Kanto Denka Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) Leorex AS-170 20 parts by weight (Daiichi Kogyo Seiyaku Co., Ltd. quaternary ammonium salt group-containing copolymer) High wax NL-500 10 parts by weight (Mitsui Petrochemical Industrial polyethylene wax) Copy Blue PR 3 parts by weight (Hoechst Industry charge control) Agent) A magnetic latent image developing toner of Example 2 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 +1.1 μC / g, and the electric resistance value was 5.
It was 4 × 10 ⁸ Ωcm.

Comparative Example 2 A magnetic latent image developing toner of Comparative Example 2 was obtained in the same manner as in Example 2 except that Printex L6 was not added and mixed. At this time, the triboelectric charge amount was +1.9 μC / g, and the electric resistance value was 1.7 × 10 ⁹ Ωcm.

Example 3 KBF-100S 250 parts by weight (Kanto Denka Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) Leorex AS-170 10 parts by weight (Daiichi Kogyo Seiyaku Co., Ltd. quaternary ammonium salt group-containing copolymer) High wax NL-500 10 parts by weight (Mitsui Petrochemical Industry polyethylene wax) Copy blue PR 3 parts by weight (Hoechst Industry charge control) Agent) A magnetic latent image developing toner of Example 3 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 −0.8 μC / g and the electric resistance value was 8.
It was 3 × 10 ¹¹ Ωcm.

Comparative Example 3 KBF-100S 250 parts by weight (Kanto Denka Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) Leorex AS-170 0.5 part by weight (Daiichi Kogyo Seiyaku quaternary ammonium salt group-containing copolymer) High Wax NL-500 10 parts by weight (Mitsui Petrochemical Industrial Polyethylene Wax) Copy Blue PR 3 parts by weight (Hoechst Industry product) Charge Control Agent) The above components were mixed, melt-kneaded, cooled to room temperature, coarsely pulverized and medium pulverized, then finely pulverized and classified by a jet mill to obtain a magnetic toner having an average particle diameter of 9 μm. 1 part by weight of T-805 (titanium oxide manufactured by Nippon Aerosil) 0.1 part by weight of Printex L6 (conductive carbon black manufactured by Degussa) 100 parts by weight of this magnetic toner was added and mixed with the above components to prepare Comparative Example 3 To obtain a toner for magnetic latent image development. At this time, the triboelectric charge amount was −3.5 μC / g and the electric resistance value was 3.6 × 10 ¹⁴ Ωcm.

Comparative Example 4 KBF-100S 250 parts by weight (Kanto Denka Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) Leorex AS-170 20 parts by weight (Daiichi Kogyo Seiyaku Co., Ltd. quaternary ammonium salt group-containing copolymer) High wax NL-500 10 parts by weight (Mitsui Petrochemical Industrial polyethylene wax) Copy Blue PR 3 parts by weight (Hoechst Industry charge control) Agent) Using the above components, a magnetic toner having an average particle size of 9 μm was prepared. 1 part by weight of T-805 (titanium oxide manufactured by Nippon Aerosil) 5 parts by weight of Printex L6 (conductive carbon black manufactured by Degussa) 100 parts by weight of this magnetic toner was mixed with the above components by external mixing to obtain the magnetic property of Comparative Example 4. A latent image developing toner was obtained. At this time, the triboelectric charge amount was +0.2 μC / g, and the electric resistance value was 7.8 × 10 ⁵ Ωcm.

Comparative Example 5 KBF-100S 250 parts by weight (Kanto Denka Kogyo ferrosoferric oxide) FC-051 120 parts by weight (Mitsubishi Rayon polyester resin) FC-344 20 parts by weight (Mitsubishi Rayon polyester resin) Leorex AS-170 35 parts by weight (Daiichi Kogyo Seiyaku quaternary ammonium salt group-containing copolymer) High wax NL-500 10 parts by weight (Mitsui Petrochemical Industrial polyethylene wax) Copy Blue PR 3 parts by weight (Hoechst Industry charge control) Agent) A magnetic latent image developing toner of Comparative Example 5 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 +2.0 μC / g, and the electric resistance value was 1.
It was 0 × 10 ⁸ Ωcm.

Comparative Example 6 KBF-100S 250 parts by weight (Kanto Denka 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 10 parts by weight (polyethylene wax manufactured by Mitsui Petrochemical Industry) Copy Blue PR 3 parts by weight (charge control agent manufactured by Hoechst Industry) Magnetic latent image of Comparative Example 6 was obtained in the same manner as in Example 1 except that the above components were used. An image developing toner was obtained. At this time, the triboelectric charge amount was −2.8 μC / g, and the electric resistance value was 9.
It was 1 × 10 ¹³ Ωcm.

Comparative Example 7 KBF-100S 250 parts by weight (Kanto Denka 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 10 parts by weight (polyethylene wax manufactured by Mitsui Petrochemical Industry) Copy Blue PR 3 parts by weight (charge control agent manufactured by Hoechst Industry) The above components were used as a magnetic toner having an average particle size of 9 microns. 1 part by weight of T-805 (titanium oxide manufactured by Nippon Aerosil) 2 parts by weight of Printex L6 (conductive carbon black manufactured by Degussa) 100 parts by weight of this magnetic toner was externally added and mixed with the components of Comparative Example 7 to obtain magnetic properties. A latent image developing toner was obtained. At this time, the triboelectric charge amount was −2.5 μC / g, and the electric resistance value was 7.0 × 10 ⁹ Ωcm.

Comparative Example 8 250 parts by weight of KBF-100S (Kanto Denka Kogyo ferrosoferric oxide) FC-051 120 parts by weight (polyester resin manufactured by Mitsubishi Rayon) 20 parts by weight of FC-344 (polyester resin manufactured by Mitsubishi Rayon) Carbon black Printex L6 15 parts by weight (Degussa conductive carbon black) High wax NL-500 10 parts by weight (Mitsui Petrochemical Industrial Polyethylene wax) Copy blue PR 3 parts by weight (Hoechst Industry charge control agent) Other than using the above components In the same manner as in Example 1, a toner for developing a magnetic latent image of Comparative Example 8 was obtained. At this time, the triboelectric charge amount was −2.1 μC / g and the electric resistance value was 8.
It was 3 × 10 ⁹ Ωcm.

Next, MG-810 manufactured by Iwasaki Tsushinki Co., Ltd.
The toner for magnetic latent image development obtained in each of the above Examples and Comparative Examples was image-outputted using a 0 type printer. 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) Amount of triboelectric charge 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 toner for developing a magnetic latent image are put in a 100 ml glass container. The mixture was mixed for 10 minutes and measured with a blow-off charge amount measuring device manufactured by Toshiba Chemical Co. 3) Head Contamination Using an MG-8100 type printer manufactured by Iwasaki Tsushinki Co., Ltd., 1 recording 1 copy was repeated 5000 times, and the adhesion of the toner to the magnetic head at that time was evaluated. ○ There is no dirt on the head or very little dirt. △ Toner adheres to the head. × Toner adheres to the head, and the image is faded during recording.

4) Electric resistance The toner for developing a magnetic latent image has a diameter of 5 at a pressure of 3 ton / cm ^2.
It was molded to have a thickness of 5.0 mm in cm and measured at a voltage of DC 10V. 5) Character sharpness ○ There is no or very slight toner scattering around the characters. △ Toner scattering around characters. × The toner is very scattered around the character, and the character appears blurred. 6) Fixing rate The reflection density of the printed 1 × 1 cm solid was measured, and then cellophane tape was attached, pressed from above with a pressure of 10 kg / cm, and the peeling reflection density was measured at a speed of 1 cm / s. . The result was calculated as (reflection density after removing cellophane tape) / (reflection density before removing cellophane tape) × 100
(%). 7) Storability After being left in a constant temperature bath at 45 ° C. for 1 week, it was sieved, and the toner blocking remaining on the mesh was visually evaluated. ○ No blocking or very little blocking. △ There is blocking of several mm square. × There is blocking of 5 mm square or more.

[0038]

[Table 1]

As shown in Table 1, a toner containing a permanent antistatic agent containing a quaternary ammonium salt group-containing copolymer and externally added with a conductive powder, the reflection density and the sharpness of the character depending on the type of paper. Does not change and a good image can be obtained. The magnetic latent image developing toners obtained in each of the examples did not increase the dust of characters and fogging even after repeated copying, provided a good image with sufficient fixability and further improved storage stability. Is obtained.

[0040]

According to the present invention, it is possible to provide a good image having good image quality, sufficient fixing property even at high speed printing, good storage stability, and stable head without stain.

Claims (3)

[Claims] 1. A magnetic latent image developing toner mainly composed of a binder resin and magnetic powder, containing 0.1 to 5 parts by weight of a permanent antistatic agent containing a quaternary ammonium salt group-containing copolymer, Then, 0.1 to 3 parts by weight of conductive powder is externally added to 100 parts by weight of the toner, and the electric resistance of the toner is in the range of 10 ⁸ to 10 ¹⁴ Ωcm. 2. The toner for developing a magnetic latent image according to claim 1, wherein the triboelectric charge amount of the toner is in the range of −5 to 5 μC / g due to the external additive and / or the charge control agent. 3. The conductive powder externally added to the toner is selected from carbon black, conductive tin oxide, conductive titanium oxide, and conductive magnetic materials.
The magnetic latent image developing toner as described above.