JPH09197708A - Magnetic toner for micr and image forming method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic toner which substantially prevents the peeling of toner image even in repetitive rubbing with a magnetic head at the time of magnetic reading, is lessened in the degradation of image quality, the staining of the images and the contamination of the magnetic head, has good offset resistance and excellent powder flowability, does not give rise to blocking, less contaminate a toner carrying member, helps the members to maintain an excellent maintaining property and lessens the damage on a fixing roll section by peeling pawls. SOLUTION: The lubricant of the magnetic toner for MICR consists of a modified polyethylene wax formed by bringing a styrene monomer and/or unsatd. carboxylic acid monomer into graft polymn. with an ethylene polymer obtd. by polymn. in the presence of a metharocene catalyst or an ethylenic copolymer consisting of ethylene and 3 to 10C α-olefin. The residual magnetization σrm of the toner particles is 4 to 7emu/g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an electrophotographic MICR.
The present invention relates to a magnetic toner used in a method for forming an image. More specifically, the present invention relates to a magnetic toner for MICR, in which a toner image fixed after printing can be read by a magnetic head or the like, and which is used for forming a good image even when repeatedly read.

[0002]

2. Description of the Related Art In electrophotography, when copying, a toner is adhered to an electrostatic latent image formed on a photoconductor using a photoconductive material by a magnetic brush developing method to develop the photoconductor. The above toner image is transferred onto a transfer body such as paper or sheet, and then fixed using heat, solvent, pressure or the like to obtain a permanent image. In order to form an image with good image quality, naturally, the toner is required to function smoothly in all processes such as development and transfer, and in the fixing process, the transferred toner image is lost. There is no need for problems such as offset and offset to be quickly fixed on the transfer body. In this way, when copying, each process is fully functioning, and the system is completed as a system with stable repeating characteristics.

In the developing step, various dry developing methods in the electrophotographic method which are currently put into practical use include a two-component developing method using a developer in which a carrier such as toner and iron powder is combined and a developing method without using a carrier. A one-component developing method using an agent is known.

The one-component developing system does not require an automatic density adjuster or the like which is necessary for a two-component developing system, so that the developing machine becomes compact, and since no carrier is used, the carrier is contaminated. No maintenance such as carrier replacement is required. Therefore, it is used not only for low-speed and small-sized devices but also for medium-speed and higher-speed copying machines and printers. Therefore, further improvement in performance is demanded.

By the way, using a one-component magnetic toner developing system using a magnetic toner containing a magnetic material in the toner, it is very easy to prepare a document suitable for magnetic image character recognition, particularly a personal check. Attempts have been made to print. In general, such a scheme is MICR (M
organic Ink Character Rec
It is called an "ignition system".

[0006] MICR is a method of magnetizing an image and reading it with a magnetic head. Usually, the image is printed by using a liquid magnetic ink, so that the image formation is not simple. Further, in recent years, a system for printing using the above-mentioned two-component developing system has been put into practical use, but since the device is large, this system is not yet simple. In that respect, the one-component magnetic toner development method is
Since the apparatus is compact and maintenance is easy, it is expected that image formation can be made more efficient.

However, in the conventional one-component developing method, the magnetization of the magnetic toner forming an image is too weak, and MI
The problem is that the CR reader cannot recognize it correctly, and furthermore, the MICR reader is designed to read a liquid-printed image. The magnetic toner that is fused and fixed by heat does not seep into the fixed image carrier such as paper, so the printed image peels off due to the pressure of the reading unit, or the tip of the writing and reading unit head peels off. There is a problem in reading, such as contamination with the formed toner.

Therefore, as a method of obtaining an appropriate magnetization which can be read by a magnetic head, a method of increasing the magnetization of a toner image, a toner adhesion amount per image or a magnetic substance content of toner particles is increased to increase the magnetic force of the toner image. A method of increasing the residual magnetism and a method of increasing the residual magnetization of the contained magnetic material have been proposed.
These methods are effective in that the magnetic force for MICR can be increased, but when actually applied for MICR, in the former case, a high pile height occurs, which causes a decrease in toner strength and the like to read MICR. There is a problem that the image is easily scraped off by the machine, and even in the latter case, it is not possible to suppress image smear (smear) and magnetic head smear (foil contamination) due to repeated rubbing with the magnetic head, and reading An error rate (reject rate) increases, and image durability (image wear), which is an important performance of MICR, becomes a practical problem. In particular, if a needle-shaped magnetic material having a high magnetic force is simply used to increase the magnetic force, the bulk density of the magnetic substance itself is greatly reduced, and the dispersibility of each material in the toner deteriorates. Will cause serious problems.

Further, the magnetic toner used for MICR is required to have both the MICR suitability described above and the suitability for the printer in the conventional one-component magnetic toner system of the electrophotographic system. In addition, considering that reading with a magnetic head is necessary, it is necessary to be epoch-making which is equivalent to or better than that of a conventional electrophotographic printer, which causes various problems in the fixing process as well as the developing process and the transfer process. Must also be able to handle. As a method for fixing a toner image, a heat melting method is most often used, but this method is roughly classified into a contact type and a non-contact type. In particular, the contact-type heating roll fixing method has been widely used in recent years in commercial copying machines, printers and the like because it has excellent thermal efficiency and enables high-speed fixing.

However, this heating roll fixing method is
There is a possibility that the toner adheres to the heating roll, causing an offset phenomenon that stains the next copy image. Particularly in high-speed copying, if the amount of heating heat per unit time is increased in order to cope with the improvement in fixing speed, the offset phenomenon is more likely to occur. Also,
In the heating roll fixing method, a peeling claw is provided at the fixing roll portion to prevent the transfer member such as paper from winding around the roll after passing through the fixing roll.

However, with the recent increase in speed of copying machines,
Due to the increased stress applied to this part, troubles such as peeling failure or image loss at the tip of the transfer body due to nails may occur when peeling, and when such image quality troubles occur, the MICR system described above is used. Due to the above characteristics, it is not possible to accurately recognize a symbol or the like when reading with a magnetic head, resulting in frequent read errors.

In order to improve the above-mentioned problems, a method of adding low molecular weight polypropylene or polyethylene as a lubricant component to the toner has been proposed (Japanese Patent Publication No. 52/52).
-3304, JP-B-52-3305, JP-B-57-52574, JP-B-58-58664, JP-A-58-59455 and JP-A-60-.
151650, etc.). However, the toner containing the above-mentioned lubricant is effective to some extent in improving the offset resistance due to poor releasability from the heating roll, suppressing peeling nail scratches and improving the rubbing resistance of the fixed image, but the effect is sufficient. is not. Further, since the compatibility of these polyolefin-based lubricants with the resin component is low, the lubricant forms large domains in the toner, and as a result, powder fluidity, cohesiveness, etc. of the toner are greatly deteriorated. In addition, some methods have been proposed to deal with toner peeling in a MICR reader and contamination of the magnetic head by the toner by using a polyolefin lubricant, but none of them is satisfactory.

In recent years, in order to save resources, a double-sided copying machine is mounted on a copying machine of a medium speed class or higher. However, when performing double-sided copying, the slipperiness of the toner image surface is increased,
In order to improve smudge property, that is, a phenomenon in which a fixed image is strongly scraped off and a toner image is peeled off and contaminated, a method of incorporating a polyolefin into a toner has been proposed. This method is effective in improving smudge property, but MI
When the same fixed image is repeatedly rubbed as in the CR system, the rubbing resistance is still insufficient in practical use.

Further, if the polyolefin is excessively added to the toner, the abrasion resistance can be expected to be improved, but as described above, the polyolefin is almost incompatible with the binder resin of the toner, so that the amount of the polyolefin is simply increased. Only by doing so, the dispersibility becomes poor, and in practice, sufficient rubbing resistance cannot be obtained in the MICR system. Furthermore, regarding the printing performance, the image density is lowered due to the contamination of the toner carrier, and the background is stained and the maintainability is deteriorated.

In order to improve the dispersibility of the polyolefin in the toner and improve the fluidity and the image forming property of the toner, Japanese Patent Laid-Open No. 251968/1990 discloses an incompatible substance such as a polyolefin with the maximum dispersion. Particle size is 5μ
A method of dispersing particles having a size of m or less has been proposed. However, although this method improves the initial image and the like, the fact that the dispersed particle size is 5 μm corresponds to half the size of the normal toner particle size (about 10 μm), It is difficult to obtain the desired dispersibility when the particles have a dispersed particle size. In particular, when this toner is used in a one-component developing system, in a long-term developability test, there is a problem such as deterioration of image maintainability due to contamination of the toner carrier.

Further, in the future toner technology, the toner particle size is gradually reduced to 7 μm and 5 μm in order to improve the image quality, so that the polyolefin having the maximum dispersed particle size of 5 μm is almost the toner particle size. Since they are equivalent, image density, background contamination, image maintainability, etc. are particularly problematic. In addition, in the case of this method, in the MICR system in which the fixed image is repeatedly rubbed very severely, since the toner contains a magnetic material, the rubbing property is lowered, and the rubbing resistance is practical. Is not enough.

Among the above-mentioned problems, as a method for solving the problem of the dispersibility of the polyolefin added to the toner,
A method in which a polyolefin is grafted to a resin to be compatible with the resin (JP-A-60-457 and JP-A-60-9).
3456, JP-A-60-93457, etc.),
A method in which a modified polyolefin is used to disperse it in a resin (JP-A-58-63947, JP-A-59-177).
570, JP 60-3644, and JP 6
2-14508, JP-A-63-191817, etc.) are known. However, these methods improve the dispersibility of the polyolefin, deteriorate the powder fluidity and the cohesiveness, etc., and can suppress the long-term development maintainability to some extent, but have an effect of improving the releasing ability that is originally required. Further, there is a problem in that MICR system cannot obtain sufficient rubbing resistance.

[0018]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned circumstances in the prior art, and has an object to improve the disadvantages thereof. That is, the object of the present invention is that the toner image is difficult to peel off even when repeatedly rubbing against the magnetic head during magnetic reading,
There is little deterioration of image quality, stain of images and contamination of magnetic head, good offset resistance, excellent powder fluidity,
It is to provide a magnetic toner for MICR that does not cause a blocking phenomenon.

Another object of the present invention is to provide a magnetic toner for MICR which is less contaminated by the toner carrier, has excellent maintainability, and is not damaged by the peeling claws of the fixing roll section. Further, another object of the present invention is to provide an image forming method using the above magnetic toner for MICR.

[0020]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that M containing a binder resin, a magnetic material and a lubricant as essential components.
It was found that the above-mentioned problems can be solved by using a magnetic toner for ICR in which a specific polymer obtained by polymerizing in the presence of a metallocene catalyst as a lubricant is graft-modified to solve the above problems, and to complete the present invention. I arrived.

That is, the magnetic toner for MICR of the present invention contains a binder resin, a magnetic material and a lubricant as essential components, and the lubricant is ethylene alone obtained by polymerization in the presence of a metallocene catalyst. From a polyethylene wax modified by graft-polymerizing a styrene monomer and / or an unsaturated carboxylic acid monomer to a polymer or an ethylene copolymer consisting of ethylene and an α-olefin having 3 to 10 carbon atoms And the residual magnetization σ _rm of the toner particles is
It is characterized by being 4 to 7 emu / g.

In the magnetic toner for MICR of the present invention, the modified polyethylene wax has a density of 0.
70-95 weight of ethylene homopolymer or ethylene-based copolymer having an average molecular weight of 95 g / cm ³ or more, an average molecular weight of 800 to 3000, and a molecular weight distribution Mw (weight average molecular weight) / Mn (number average molecular weight) of 1.1 to 1.8. Part, a polyethylene wax having a melt viscosity at 160 ° C. of 15 to 250 cps and a penetration of 2 dmm or less, which is modified by graft-polymerizing 5 to 30 parts by weight of a styrene monomer and / or an acrylic monomer. It is preferable to use.

In the image forming method of the present invention, a latent image is formed on the latent image holding member, the latent image is developed with a developer, and the developed toner image is transferred onto the transfer member. And a step of heating and fixing the toner image on the transfer body, wherein the magnetic toner for MICR is used as the developer.

In the present invention, when a magnetic toner containing the above-mentioned binder resin, magnetic material and modified polyethylene wax is used in the MICR printing method, even if the modified polyethylene wax is highly dispersed in the toner. In addition, it is easy to control so as to sufficiently obtain the releasing ability without impairing the powder fluidity, cohesiveness and charging property of the toner. Further, since the modified polyethylene wax itself is uniformly dispersed on the toner surface and does not contain an extremely low molecular weight component, even if it is exposed on the toner surface, it does not cause contamination of the toner carrier during long-term use. Therefore, it is possible to exhibit sufficient rubbing resistance in the reader of the MICR system without lowering the developability.

Further, the polyethylene wax used as a lubricant in the present invention is obtained by polymerizing using a metallocene catalyst, and is a method of degassing under vacuum at a temperature above the melting point, such as hexane and acetone. It can be obtained by a method of controlling the molecular weight distribution (Mw / Mn) only by removing the low molecular weight portion by dissolving it in a solvent or by dissolving the entire amount in the solvent and then removing the high molecular weight portion by precipitating at a specific temperature. Unlike waxes and the like, since the molecular structure / chain length can be regularly regulated at the time of wax polymerization, it is possible to synthesize polyethylene wax having a higher density even in the low molecular weight region. It is effective, and balances various properties such as molecular weight distribution and viscosity characteristics. On reluctant control it is easy to, as described later, can be performed efficiently even for the modification.

[0026]

Embodiments of the present invention will be described below in detail. The lubricant used in the present invention is
An ethylene homopolymer or an ethylene copolymer composed of ethylene and an α-olefin having 3 to 10 carbon atoms is graft-modified, wherein the ethylene homopolymer or ethylene copolymer has a metallocene catalyst. It was obtained by polymerizing below. The metallocene catalyst is
It can be used without any particular limitation. For example, a metallocene catalyst comprising a combination of (A) a compound of a transition metal selected from the group consisting of groups IVb, Vb and VIb of the periodic table (hereinafter referred to as “transition metal compound”) and (B) a cocatalyst. Is exemplified. Examples of the above-mentioned transition metal compound include compounds represented by the following general formula (1). ML _x (1)

In the above general formula (1), M represents a transition metal atom selected from Group IV metals, zirconium, titanium,
Hafnium etc. are illustrated. x is the valence of the transition metal and represents the number of L. L represents a ligand or group that coordinates to a transition metal, at least one L is a ligand having a cyclopentadienyl skeleton such as cyclopentadienyl, indenyl, and other L is A hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, a trialkylsilyl group, SO ₃ R ¹ (wherein R ¹ is a carbon atom having 1 to 8 carbon atoms which may have a substituent such as halogen). Hydrogen group), a halogen atom and a hydrogen atom. Furthermore, the above general formula (1)
When the compound shown by contains two or more ligands having a cyclopentadienyl skeleton, the ligands having two cyclopentadienyl skeletons among them are alkylene groups such as ethylene and propylene, and isopropylidene. Or a substituted alkylene group such as diphenylmethylene, a silylene group, or a substituted silylene group such as a dimethylsilylene group or a diphenylsilylene group.

Examples of such compounds include bis (cyclopentadienyl) zirconium dichloride, bis (methylcyclopentadienyl) zirconium dichloride, bis (ethylcyclopentadienyl) zirconium dichloride and bis (n-propylcyclo). Pentadienyl) zirconium dichloride, bis (n-butylcyclopentadienyl) zirconium dichloride, bis (n-
Hexylcyclopentadienyl) zirconium dichloride, bis (methyl-n-propylcyclopentadienyl) zirconium dichloride, bis (methyl-n-butylcyclopentadienyl) zirconium dichloride, bis (dimethyl-n-butylcyclopentadienyl) ) Zirconium dichloride, bis (n-butylcyclopentadienyl) zirconium dibromide, bis (n-butylcyclopentadienyl) zirconium methoxychloride,
Bis (n-butylcyclopentadienyl) zirconium ethoxy chloride, bis (n-butylcyclopentadienyl) zirconium butoxycyclolide, bis (n-butylcyclopentadienyl) zirconium ethoxide, bis (n-butylcyclopentadiene) (Enyl) zirconium methyl chloride, bis (n-butylcyclopentadienyl) dimethyl zirconium, bis (n-butylcyclopentadienyl) zirconium benzyl chloride, bis (n-butylcyclopentadienyl) dibenzyl zirconium, bis (n -Butylcyclopentadienyl) zirconium phenyl chloride, bis (n-butylcyclopentadienyl) zirconium hydride chloride, ethylenebis (indenyl) dimethylzirconium, ethylenebis (indenyl) Diethylzirconium, ethylenebis (indenyl) diphenylzirconium, ethylenebis (indenyl) methylzirconium monochloride, ethylenebis (indenyl) ethylzirconium monochloride, ethylenebis (indenyl) methylzirconium monobromide, ethylenebis (indenyl) zirconium dichloride, ethylene Bis (indenyl) zirconium dibromide, ethylene bis {1- (4,5,5
6,7-Tetrahydroindenyl)} dimethylzirconium, ethylenebis {1- (4,5,6,7-tetrahydroindenyl)} methylzirconium monochloride,
Ethylene bis {1- (4,5,6,7-tetrahydroindenyl)} zirconium dichloride, ethylene bis {1- (4,5,6,7-tetrahydroindenyl)}
Zirconium dibromide, ethylenebis {1- (4-methylindenyl)} zirconium dichloride, ethylenebis {1- (5-methylindenyl)} zirconium dichloride, ethylenebis {1- (6-methylindenyl)} zirconium Dichloride, ethylene bis {1-
(7-methylindenyl)} zirconium dichloride,
Ethylenebis {1- (5-methoxyindenyl)} zirconium dichloride, ethylenebis {1- (2,3-dimethylindenyl)} zirconium dichloride, ethylenebis {1- (4,7-dimethylindenyl)} zirconium Dichloride, ethylenebis {1- (4,7-dimethoxyindenyl)} zirconium dichloride, isopropylidene (cyclopentadienyl-fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-2,7-di-t-butyl) Fluorenyl) zirconium dichloride, isopropylidene (cyclopentadienyl-methylcyclopentadienyl) zirconium dichloride, dimethylsilylene bis (cyclopentadienyl) zirconium dichloride, dimethylsilylene bis (methylcyclo) N-dienyl) zirconium dichloride, dimethylsilylenebis (dimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (trimethylcyclopentadienyl) zirconium dichloride, dimethylsilylenebis (indenyl) zirconium dichloride, diphenylsilylenebis (indenyl) zirconium dichloride, etc. can give. In the above examples, the disubstituted product of the cyclopentadienyl ring includes 1,2- and 1,3-substituted products, and the trisubstituted product is 1,2,3- and 1,2,4. -Including substitutions. In the present invention, a transition metal compound in which zirconium metal is replaced with titanium metal or hafnium metal in the zirconium compound as described above can be used.

As the co-catalyst (B), conventionally known ones can be used without particular limitation. For example, the compound (B-2) which reacts with the aluminoxane (B-1) or the transition metal compound (A) to form an ionic complex can be mentioned.

Specific examples of the aluminoxane (B-1) include organic aluminum compounds represented by the following general formula (2) or (3).

Embedded image (In the formula, R ² represents a hydrocarbon group, and m represents an integer of 2 or more.)

In the above aluminoxane, R ² is methyl group, ethyl group, propyl group, n-butyl group, iso
-Butyl group, phenyl group, phenylmethyl group and the like are exemplified, and methyl group, ethyl group and iso-butyl group are preferable. m is an integer of 2 or more, preferably 3 to 50, and particularly preferably 3 to 40.

The aluminoxane can be obtained by, for example, (1) adding a compound containing adsorbed water or a salt containing water of crystallization, for example, to a hydrocarbon medium suspension such as magnesium hydrate and copper sulfate hydrate. A method of reacting an organoaluminum compound such as alkylaluminum to recover it as a hydrocarbon solution, (2) by directly acting water, ice, or steam on the organoaluminum compound such as trialkylaluminum in a medium such as benzene or toluene. There is a method of recovering as a hydrocarbon solution, and the organic aluminum compound used is trimethylaluminum, triethylaluminum, tripropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-aluminum.
Examples include sec-butylaluminum, tri-tert-butylaluminum, triisopentylaluminum and the like.

As the compound (B-2) which reacts with the transition metal compound (A) to form an ionic complex, for example, a compound consisting of a cation and an anion in which a plurality of groups are bound to an element, particularly, Coordination complex compounds can be mentioned as preferable ones. Specific compounds include trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, tri (n-butyl) ammonium tetraphenylborate, trimethylammonium tetra (pentafluorophenyl) borate, triethylammonium tetra (pentafluorophenyl) borate,
Tri (n-butyl) ammonium tetra (pentafluorophenyl) borate, Triethylammonium hexafluoroarsenate, Ferrocenium tetraphenylborate, Trityl tetraphenylborate, Ferrocenium tetra (pentafluorophenyl) borate, Methylferrotetra (pentafluorophenyl) borate Cenium, decamethylferrocenium tetra (pentafluorophenyl) borate, silver tetra (pentafluorophenyl) borate, trityl tetra (pentafluorophenyl) borate, silver tetrafluoroborate, silver hexafluorophosphate, silver hexafluoroarsenate , Silver perchlorate, silver hexafluoroantimonate, silver trifluoroacetate, silver trifluorometasulfonate, tetra (pentafluorophenyl) borate (N-benzyl-2
-Cyanopyridinium), tetra (pentafluorophenyl) borate (N-benzyl-3-cyanopyridinium), tetra (pentafluorophenyl) borate (N-benzyl-4-cyanopyridinium), tetra (pentafluorophenyl) borate (N -Methyl-2-cyanopyridinium), tetra (pentafluorophenyl) boric acid (N
-Methyl-3-cyanopyridinium), tetra (pentafluorophenyl) borate (N-methyl-4-cyanopyridinium), trimethylammonium tetra (pentafluorophenyl) borate, trimethyl tetra (pentafluorophenyl) borate (m-trifluoro) Methylphenyl) ammonium, tetra (pentafluorophenyl)
Examples thereof include benzylpyridinium borate.

If necessary, an organoaluminum compound (C) may be used together with these promoters (B). As such an organoaluminum compound, a compound represented by the following general formula (4) can be exemplified. R ¹ _n AlX _3-n (4) (In the formula, R ¹ represents a hydrocarbon group having 1 to 12 carbon atoms;
Represents a halogen atom or a hydrogen atom, and n is an integer of 1 to 3. )

In the above general formula (4), R ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, for example, an alkyl group, a cycloalkyl group or an aryl group. Specifically, a methyl group, an ethyl group, Examples thereof include n-propyl group, iso-propyl group, iso-butyl group, pentyl group, hexyl group, octyl group, cyclopentyl group, cyclohexyl group, phenyl group and tolyl group. As such an organoaluminum compound, trimethylaluminum,
Trialkylaluminums such as triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, tri-2-ethylhexylaluminum; alkenylaluminums such as isoprenylaluminum; dimethylaluminum chloride, diethylaluminium chloride, diisopropylaluminum chloride, diisobutyl. Dialkyl aluminum halides such as aluminum chloride and dimethyl aluminum bromide; alkyl aluminum sesquihalides such as methyl aluminum sesquichloride, ethyl aluminum sesquichloride, isopropyl aluminum sesquichloride, butyl aluminum sesquichloride and ethyl aluminum sesquibromide; methyl aluminum dichloride De, ethylaluminum dichloride, isopropyl aluminum dichloride, alkyl aluminum dihalides such as ethyl aluminum dibromide; diethylaluminum hydride, compounds such as alkyl aluminum hydride such as diisobutyl aluminum hydride are used.

In the present invention, the above transition metal compound (A)
And a co-catalyst (B), and if necessary, a metallocene catalyst composed of the organoaluminum compound (C) represented by the general formula (4). The polymerization reaction is carried out in a hydrocarbon medium. Specific examples of the hydrocarbon medium include butane, isobutane, pentane, hexane, octane, decane, dodecane, hexadecane, octadecane and other aliphatic hydrocarbons, cyclopentane, methylcyclopentane, cyclohexane, cyclooctane and other alicyclic rings. In addition to group hydrocarbons, aromatic hydrocarbons such as benzene, toluene, and xylene, petroleum fractions such as gasoline, kerosene, and light oil, olefin as a raw material also serves as a hydrocarbon medium. Of these hydrocarbon media, aromatic hydrocarbons are preferred.

In the present invention, the ratio of the transition metal compound used when the polymerization reaction is carried out by the liquid phase polymerization method is usually 10 ^-8 to 10 as the concentration of the transition metal atom in the polymerization reaction system.
10 ^-2 gram atom / liter, preferably 10 ^-7 to 10
^-3 gram atoms / liter. The proportion of aluminoxane used is usually in the range of 10 ^-4 to 10 ^-1 gram atom / liter, preferably 10 ^-3 to 10 ^-2 gram atom / liter, as the concentration of aluminum atom in the polymerization reaction system. Is. The ratio of aluminum atom to transition metal atom in the polymerization reaction system is usually 4 to 10 ⁷ , preferably 10 to 10 ⁶ .

In the present invention, the molecular weight of the ethylene homopolymer or ethylene copolymer can be adjusted by hydrogen and / or polymerization temperature. The temperature at the time of the polymerization reaction is usually 20 ° C. or higher, particularly preferably 50 ° C.
It is in the range of ~ 230 ° C. The amount of hydrogen supplied to the polymerization reaction is usually 0.01 to 50 as a molar ratio of hydrogen to ethylene.
4, preferably in the range of 0.05 to 2.

In the present invention, an ethylene homopolymer obtained by polymerization in the presence of these metallocene catalysts or an ethylene copolymer comprising ethylene and an α-olefin having 3 to 10 carbon atoms is used. The intrinsic viscosity [η] measured in decalin at 135 ° C is preferably 0.4d.
1 / g or less, particularly preferably 0.005 to 0.35 dl
/ G range. In the case of a copolymer, the proportion of ethylene in the constituent monomers is usually 80 mol% or more, preferably 85 mol% or more.

Further, the ethylene homopolymer or ethylene copolymer thus obtained has a viscosity average molecular weight of 800 to 3000 and a density of 0.95 g / cm ^3.
It is more preferable that the penetration is 2 dmm or less, and further 1 dmm or less. Polyethylene in this range has a high density and its molecule is linear, so that it has self-lubricating property, and therefore, the toner obtained by using it has a toner on the surface of the fixed image. It is possible to reduce damage due to abrasion and prevent rubbing stains, bleeding, and the like on the fixed image. That is, after passing through the heating roll, a film having lubricity is formed on the surface of the fixed image, and the lubrication effect is sufficiently exhibited.

The molecular weight distribution (Mw / Mn) of the above ethylene homopolymer or ethylene copolymer (hereinafter referred to as "polyethylene wax") used in the present invention determined by gel permeation chromatography is: Usually, it is preferably in the range of 1.1 to 1.8, and 1.1
The range of -1.5 is more preferable. Molecular weight distribution Mw / Mn
Is within this range, it is possible to reduce the component having a large molecular weight and the component having a small molecular weight in the polyethylene wax within the above range of the viscosity average molecular weight.
This eliminates the blocking property due to the component having a small molecular weight that starts melting at a low temperature, the deterioration of the powder fluidity at room temperature, and the reduction in the effect of suppressing peeling nail scratches due to the partial increase in the melt viscosity of the component having a large molecular weight. It is possible.

This also has a great influence on the melting behavior of the polyethylene wax itself. In general, polyethylene wax maintains a completely solid state in a normal state, and when passing through a fixing roll, it is completely melted in the vicinity of a set temperature of the fixing roll during the extremely short passage time, and an effect is exhibited. Is required. When the molecular weight distribution is controlled within the above range, the melting temperature range for finishing the melting can be narrowed as compared with the wax which is usually used. As a result, the amount of wax that contributes to release (the amount of wax that dissolves at the set temperature of the fixing roll) increases, and efficiency is improved from the viewpoint of the effect of manifestation. The metallocene-based catalyst can obtain a polymer having a narrower molecular weight distribution than conventional catalyst systems. Therefore, it is not necessary to narrow the molecular weight distribution in the steps such as the method of distilling, crystallization and solvent washing, or even if it is necessary, it can be efficiently carried out.

The molecular weight distribution (Mw / Mn) of the polyethylene wax used in the present invention is G, manufactured by Waters Corporation.
It is a value measured using PC150C at a temperature of 140 ° C. and o-dichlorobenzene as a solvent at a measurement flow rate of 1.0 ml / min at a concentration of 0.1% by weight. In calculating the molecular weight of the sample, the viscosity equation of polyethylene was used. As the column, Tohso GMH-HT (60c
m) and GMH-HTL (60 cm) were used in combination. The penetration is JIS K2207 and the density is JI.
According to SK 6760, the melt viscosity is 160
It was heated and melted at 0 ° C. and measured by a Brookfields viscometer.

The polyethylene wax produced by the above method is further degassed under vacuum at a temperature above the melting point, or dissolved in a solvent such as hexane or acetone to remove the low molecular weight portion, or the polyethylene wax is completely dissolved in the solvent. After that, a method of removing the high molecular weight portion by precipitating at a specific temperature may be used together. Further, the graft modification ratio of the styrene-based monomer or the unsaturated carboxylic acid-based monomer to the polyethylene wax is preferably 5 to 30 parts by weight when the total weight is 100 parts. Within this range, adverse effects on powder fluidity, blocking properties, caking resistance, etc. due to large domains, release effect due to excessive dispersion of lubricant in the toner, reduction in rubbing resistance, etc. And can show good performance.

Examples of the styrenic monomer used for the graft polymerization in the present invention include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene,
4-methylstyrene, 2,5-dimethylstyrene, 3,
4-dimethylstyrene, 2,4,6-trimethylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4--
Butyl styrene, 4-sec-butyl styrene, 4-t
ert-butyl styrene, 4-hexyl styrene, 4-
Nonylstyrene, 4-octylstyrene, 4-phenylstyrene, 4-decylstyrene, 4-dodecylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 2,4-dichlorostyrene, 3,4-dichlorostyrene, 2-methoxystyrene, 4-methoxystyrene, 4-ethoxystyrene, etc. can be mentioned.

As the unsaturated carboxylic acid type monomer used for the graft polymerization, methyl acrylate, ethyl acrylate, butyl acrylate, sec-butyl acrylate, isobutyl acrylate, propyl acrylate, Isopropyl acrylate, 2-octyl acrylate, dodecyl acrylate, stearyl acrylate, hexyl acrylate, isohexyl acrylate, phenyl acrylate, 2-chlorophenyl acrylate, diethylaminoethyl acrylate, 3-methoxybutyl acrylate, acrylic acid Diethylene glycol ethoxylate,
Acrylic esters such as 2,2,2-trifluoroethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, sec-butyl methacrylate, isobutyl methacrylate, propyl methacrylate,
Isopropyl methacrylate, 2-octyl methacrylate, dodecyl methacrylate, stearyl methacrylate,
Methacrylic acid esters such as hexyl methacrylate, decyl methacrylate, phenyl methacrylate, 2-chlorohexyl methacrylate, diethylaminoethyl methacrylate, 2-ethylhexyl methacrylate, 2,2,2-trifluoroethyl methacrylate, and others, Maleic acid esters such as ethyl maleate, propyl maleate, butyl maleate, diethyl maleate, dipropyl maleate and dibutyl maleate, fumaric acid esters such as ethyl fumarate, butyl fumarate and dibutyl fumarate, itaconic acid Itaconic acid esters such as ethyl, diethyl itaconate and butyl itaconate may be mentioned.

The styrene-based monomer or unsaturated carboxylic acid-based monomer graft-polymerized on the polyethylene wax has been exemplified above, but the present invention is not limited thereto. The amount of the modified polyethylene wax added to the toner is preferably 1 to 20% by weight, more preferably 2 to 8% by weight, based on the weight of the toner.

As a method for modifying the polyethylene wax with the above-mentioned monomer, various known methods can be adopted. For example, a method in which a polyethylene wax and a styrene-based monomer or an unsaturated carboxylic acid-based monomer are heated and melt-mixed in the presence of a radical initiator and reacted, can be used. In that case, the reaction temperature is 125 to 325.
The temperature range is preferably in the range of ° C, and the radical initiator to be used includes peroxides such as benzoyl peroxide, lauroyl peroxide, dicumyl peroxide, di-t-butyl peroxide, and azo compounds such as azobisisobutyronitrile. Can be given.

The melt viscosity of the modified polyethylene wax is preferably 15 to 250 cps at 160 ° C. In this range, the cohesive strength of the fixed image immediately after passing through the heating roll and the melt viscosity of the image surface are appropriately controlled, image scraping by the peeling nail, defective release, and peeling nail scratches due to excessive stress during releasing are generated. It is possible to suppress. In particular, in the polyethylene wax produced by the above method, the polyethylene wax using the metallocene-based catalyst as described above can be used while maintaining a balance with other physical properties of the wax within the above range of viscosity average molecular weight. It has an advantage that it is easy to control so as to exhibit the melt viscosity of.

The modified polyethylene wax preferably has a penetration of 2 dmm or less, particularly 1 dmm or less. The modified polyethylene wax having a penetration of the above range has self-lubricating property, and therefore reduces damage due to abrasion of the surface of the fixed image and prevents rubbing stains, bleeding, etc. on the fixed image. You can That is, after passing through the heating roll, a film having lubricity is formed on the surface of the fixed image, and the lubricating effect is sufficiently exhibited. The amount of the modified polyethylene wax added to the toner is appropriately in the range of 1 to 20% by weight based on the weight of the toner.
% Is more preferred.

The binder resin used in the present invention includes styrenes such as styrene, chlorostyrene and vinyl styrene,
Vinyl acetate, vinyl propionate, vinyl benzoate, vinyl butyrate and other vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, Butyl methacrylate, α-methylene aliphatic monocarboxylic acid ester such as dodecyl methacrylate, vinyl methyl ether, vinyl ethyl ether, vinyl ether such as vinyl butyl ether, homopolymer or copolymer such as vinyl methyl ketone, further polyester, Examples of the binder resin include polyurethane, epoxy resin, silicone resin, and polyamide. Particularly, typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, and styrene-alkyl methacrylate copolymer. Body, styrene - acrylonitrile copolymer, styrene - butadiene copolymer, styrene - can be exemplified maleic anhydride copolymer, not limited to these examples.

The magnetic toner for MICR of the present invention contains a magnetic substance as one of the main constituents, and the magnetic substance may be any known magnetic substance that has been generally used in the past. Although they can be used, needle-like magnetic bodies and doped magnetic bodies are preferable. Further, the heat-treated magnetic material, for example, a cubic magnetic material is heated and oxidized in an oxygen atmosphere at 700 ° C. for 100 minutes, and then cooled.
The product obtained by heating and reducing in a hydrogen atmosphere at 00 ° C. for 200 minutes, crushing after cooling, has good dispersibility and excellent development stability such as environmental stability. It is preferable because a magnetic toner can be obtained.

The residual magnetization σ _rm of the magnetic material used is preferably in the range of 7 to 24 emu / g, more preferably 7 to 16 emu / g, particularly preferably 8 to
It is in the range of 14 emu / g. Remanent magnetization σ of magnetic material
_{When rm} is less than 7 emu / g, the magnetization is weak and the symbols and the like cannot be recognized accurately. On the other hand, 24 emu /
When it exceeds g, the magnetization is too strong to recognize the symbol or the like accurately.

In the magnetic toner for MICR of the present invention, the residual magnetization σ _rm in the toner particles is 4 to 7 emu / g.
It is necessary to be in the range of, preferably 4.2 to 7
emu / g, more preferably 4.5 to 6.5 emu / g
g. Remanent magnetization σ _{rm in} toner particles is 4 em
If it is less than u / g, the magnetization is weak and the symbol or the like cannot be accurately recognized. On the other hand, if it exceeds 7 emu / g,
The magnetization is too strong to recognize the symbols accurately. The content of the magnetic substance in the toner particles is preferably in the range of 20 to 80% by weight, and 3
The range of 0 to 70% by weight is more preferable, and the range of 40 to 60% by weight is particularly preferable. Further, the MIC in the present invention
The magnetic toner for R may contain known additives such as a charge control agent substance, if necessary, and further externally add other inorganic compound fine particles such as a fluidity improver including colloidal silica fine particles. You may.

The image forming method of the present invention can be carried out by using the above-mentioned MICR magnetic toner in the conventionally known image forming step. The electrostatic latent image holding member is an organic photoconductor, Amorphous silicon-based photoconductors, or those whose surface is overcoated if necessary, and any known ones can be used as long as they can be applied to a printer in a conventional electrophotographic magnetic one-component toner system. Is.

[0056]

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the following description, "part" means "part by weight". (Production Example of Polyethylene Wax Using Metallocene Catalyst) Production Example a Using a continuous polymerization reactor, 200 liters / hr of purified hexane and 0.4 mol of methylaluminoxane (manufactured by Tosoh Akzo Co., Ltd.) in terms of aluminum atom. / Hr, 0.2 mol of trimethylaluminum / hr and bis (n-
Butylcyclopentadienyl) zirconium dichloride was continuously supplied at a rate of 2 mmol / hr in terms of zirconium atom, and in the gas phase in the polymerization reactor, the ratio of hydrogen to ethylene (H ₂ / C ₂ H ₄ ) Is 0.40, total pressure is 3
Ethylene and hydrogen were continuously fed so as to obtain 0 kg / cm ² G, polymerization temperature 140 ° C., atmospheric pressure, residence time 0.5
Polymerization was carried out under conditions such that the polymer concentration was 90 g / liter for an hour. To 1 liter of the obtained polymer solution,
After adding 5 liters of methanol to precipitate the polymer, the polymer was recovered by filtration and dried to obtain a polymer having the following physical properties. [Η]: 0.08 dl / g,
Molecular weight distribution Mw / Mn: 1.3, viscosity average molecular weight: 11
30, density: 0.96 g / cm ³ , melt viscosity at 160 ° C .: 12.0 cps.

Production Example b Production Example a except that the ratio of hydrogen to ethylene (H ₂ / C ₂ H ₄ ) in the gas phase in the polymerization reactor was changed to 0.50 in the polymerization reaction of Production Example a. The polymerization reaction was performed in the same manner as in. The physical properties of the obtained polymer were as follows. [Η]: 0.06 dl / g, molecular weight distribution Mw / Mn:
1.2, viscosity average molecular weight: 890, density: 0.96 g /
cm ³ , melt viscosity at 160 ° C .: 7.7 cps.

(Production Examples of Various Graft-Modified Polyethylene Waxes) Production Example 1 Polyethylene Wax Production Example a Using Metallocene Catalyst
Polyethylene wax ([η]: 0.0
8 dl / g, molecular weight distribution Mw / Mn: 1.3, viscosity average molecular weight: 1130, density: 0.96 g / cm ³ , 160
Melt viscosity at ℃: 12.0 cps) 1000 g 1
Melts at 60 ° C., 250 g of styrene, di-
21 g of tert-butyl peroxide was added dropwise via a separate conduit over 4 hours. After the dropping was completed, the reaction was continued at 160 ° C. for 1 hour, and then 30 m in order to remove volatile matter.
Degassing was performed under a vacuum of mHg for 1 hour to obtain a modified polyethylene wax (penetration: 1 dmm or less, melt viscosity at 160 ° C .: 23.7 cps).

Production Example 2 Polyethylene Wax Production Example b Using Metallocene Catalyst
Polyethylene wax ([η]: 0.0
6 dl / g, molecular weight distribution Mw / Mn: 1.2, viscosity average molecular weight: 890, density: 0.96 g / cm ³ , 160 ° C.
A modified polyethylene wax (penetration: 1 dmm or less, melt viscosity at 160 ° C .: 17.0 cps) was obtained in the same manner as in Production Example 1 except that 1000 g of melt viscosity in (7) cps was used. Production Example 3 In the same manner as in Production Example 1 except that a mixture of 125 g of styrene and 125 g of dibutyl fumarate was used instead of 250 g of styrene, a modified polyethylene wax (penetration:
1dmm or less, melt viscosity at 160 ° C: 18.0c
ps) was obtained.

Production Example 4 A modified polyethylene wax (penetration: 1 dm) was prepared in the same manner as in Production Example 1 except that 125 g of styrene and 125 g of butyl methacrylate were used instead of 250 g of styrene.
m or less, melt viscosity at 160 ° C .: 20.0 cps)
I got Production Example 5 Polyethylene wax (viscosity average molecular weight: 1070, molecular weight distribution: Mw / Mn: 2.61, density: 0.97 g /
cm ³ , melt viscosity at 160 ° C .: 85.0 cps)
A modified polyethylene wax (penetration: 1 dmm or less, 16 g) was produced in the same manner as in Production Example 1 except that 1000 g was used.
A melt viscosity at 0 ° C .: 210.0 cps) was obtained.

Production Example 6 Instead of 250 g of styrene, 20 g of styrene, di-t
except that 1.7 g of ert-butyl peroxide was used,
In the same manner as in Production Example 1, modified polyethylene wax (penetration: 1 dmm or less, melt viscosity at 160 ° C .: 1
2.0 cps) was obtained. Production Example 7 A modified polyethylene wax (penetration: 2 dm was used in the same manner as in Production Example 1 except that 125 g of styrene and 540 g of dibutyl fumarate were used instead of 250 g of styrene.
m, melt viscosity at 160 ° C .: 130.0 cps) was obtained. Production Example 8 Polypropylene wax (viscosity average molecular weight: 3000,
Molecular weight distribution: Mw / Mn: 2.75, density: 0.89 g
/ Cm ³ , melt viscosity at 160 ° C .: 70.0 cp
s) In the same manner as in Production Example 1 except that 1000 g was used, modified polypropylene wax (penetration: 1 dmm,
Melt viscosity at 180 ° C .: 250.0 cps) was obtained.

Example 1 (Preparation of Toner) Styrene-butyl methacrylate copolymer (weight ratio 85/15) 82 parts (Mw = 1.8 × 10 ⁵ ) Magnetic material (heat treated magnetite) 100 parts (remanent magnetization: σ _rm = 12.0 emu / g) (Shape: amorphous, BET: 6.3 cm ² / mg) Charge control agent (T-77, Hodogaya Chemical Co., Ltd.) 1.5 parts Modified polyethylene wax shown in Production Example 1 10 parts The above components were powder-mixed with a Banbury mixer, and melt-kneaded with an extruder having a preset temperature of 140 ° C. After cooling, finely pulverize, classify with a classifier,
Toner particles having an average particle diameter of 8.4 μm were obtained. 0.6% by weight of hydrophobic colloidal silica was externally added to the particles by a Henschel mixer to obtain a magnetic toner. The residual magnetization (σ _rm ) in the obtained toner particles was 6.0 emu / g.

Example 2 A magnetic toner was obtained in the same manner as in Example 1 except that the modified polyethylene wax shown in Production Example 2 was used as the lubricant. The remanent magnetization (σ _rm ) in the obtained toner particles is 6.
It was 0 emu / g. Example 3 A magnetic toner was obtained in the same manner as in Example 1 except that the modified polyethylene wax shown in Production Example 3 was used as the lubricant. The remanent magnetization (σ _rm ) in the obtained toner particles is 6.
It was 0 emu / g. Example 4 A magnetic toner was obtained in the same manner as in Example 1 except that the modified polyethylene wax shown in Production Example 4 was used as the lubricant. The remanent magnetization (σ _rm ) in the obtained toner particles is 6.
It was 0 emu / g.

Comparative Example 1 Polyethylene wax ([η]: 0.13) was used as a lubricant.
dl / g, molecular weight distribution Mw / Mn: 2.61, viscosity average molecular weight: 2000, density: 0.97 g / cm ³ , 160
A magnetic toner was obtained in the same manner as in Example 1 except that the melt viscosity at 5 ° C .: 55.0 cps) was used. Comparative Example 2 As a lubricant, polypropylene wax (viscosity average molecular weight: 3000, molecular weight distribution Mw / Mn: 2.75, density: 0.89 g / cm ³ , melt viscosity at 160 ° C .:
A magnetic toner was obtained in the same manner as in Example 1 except that 70.0 cps) was used.

Comparative Example 3 A magnetic toner was obtained in the same manner as in Example 1 except that the modified polyethylene wax shown in Production Example 5 was used as the lubricant. Comparative Example 4 A magnetic toner was obtained in the same manner as in Example 1 except that the modified polyethylene wax shown in Production Example 6 was used as the lubricant. Comparative Example 5 A magnetic toner was obtained in the same manner as in Example 1 except that the modified polyethylene wax shown in Production Example 7 was used as the lubricant. Comparative Example 6 A magnetic toner was obtained in the same manner as in Example 1 except that the modified polypropylene wax shown in Production Example 8 was used as the lubricant.

The test methods and evaluation criteria in each of the above Examples and Comparative Examples are as follows. (1) Offset temperature The offset temperature was measured using a Vivace 550 (modified) fixing device (manufactured by Fuji Xerox Co., Ltd.). Heat roll temperature 180 ℃
Further, the temperature at which the offset occurred was visually checked by raising the temperature to 250 ° C in 5 ° C increments. (Note that "not generated" is 250 ℃
Indicates that the occurrence of offset is not confirmed. (2) Peeling Claw Disappearance Temperature Measured using a Vivace 550 (modified) fixing device. This indicates the heat roll temperature at which the peeling nail scratches generated in the solid black image at the leading end of the image reach a level that does not pose a problem in practical use. (Note that "not generated" means the lower limit temperature of measurement 1
This indicates that no peeling nail was generated even at 40 ° C. )

(3) Storage stability In each Example and Comparative Example, toner particles before external addition of hydrophobic colloidal silica were used, and the temperature was 50 ° C./50%.
A 17-hour storage test was performed in an RH atmosphere. Then, it was subjected to a vibrating screen for 5 minutes with a 63 μm screen to confirm the blocking property. G1: Passage rate of 63 μm sieve is 70% or more G2: Passage rate of 63 μm sieve is 40% or more and less than 70% G3: Passage rate of 63 μm sieve is less than 40% (4) Toner transport amount In each Example and Comparative Example, hydrophobicity The toner particles before external addition of colloidal silica were used, and the amount of toner conveyed per hour was measured using a Vivace 800 (modified) toner box as an index of powder fluidity. (5) Image Density Each sample was sampled by a modified printer 4197 (manufactured by Fuji Xerox Co., Ltd.). The image density of the solid portion at the initial stage and after copying 10,000 sheets was measured using an X-Rite densitometer.

(6) Rubbing resistance The obtained magnetic toner was evaluated by a modified printer 4197 (manufactured by Fuji Xerox Co., Ltd.). Approximately 500 sheets printed on check paper are actually read by a leader sorter (IBM
-3890 MICR Reader Sorter)
30 times to evaluate. In this case, the following three evaluations are performed. The following (a) and (b) are considered to cause the read error. Further, (c) below is the actual error rate, and includes errors due to causes other than (a) and (b). (A) Image dirt (smear) A phenomenon in which the area around the characters and the background are smeared by the toner that has been peeled off or scraped off from the characters by rubbing. A rank sample for this phenomenon was created and evaluated. (B) Head Contamination (Foil Contamination) A phenomenon in which toner that has been peeled off or scraped from the character portion due to rubbing adheres to the protective tape of the head. A rank sample for this phenomenon was created and evaluated. In addition, the above (a)
The evaluation criteria of (b) are as follows. G1: Very good G2: Good G3: Practically good G4: Practical limit G5: Practically unusable G6: Poor (c) Reading error rate (reject trait) If the reader sorter cannot read, an error occurs. Automatically excluded as. The error rate at that time is%
Expressed by Here, the reading error rate% is represented by (excluded number / total number of passed sheets) × 100. The evaluation criteria of this (c) are as follows. G1: 0 to 0.5%, very good G2: 0.5 to 1.5%, good G3: 1.5 to 5%, practical limit G4: 4.5% or more, unusable for use

The properties of the lubricant used in the magnetic toners obtained in Examples 1 to 4 and Comparative Examples 1 to 6 are shown in Table 1.
Table 2 and Table 3 show the characteristic evaluation conditions and results measured using these magnetic toners.

[Table 1]

[0070]

[Table 2]

[0071]

[Table 3]

[0072]

Industrial Applicability The magnetic toner for MICR of the present invention comprises a binder resin, a magnetic material and a lubricant as essential components, an ethylene homopolymer obtained by polymerization in the presence of a metallocene catalyst in the lubricant, or ethylene and a carbon number. Good offset resistance by using polyethylene wax modified by graft-polymerizing styrene monomer or unsaturated carboxylic acid monomer to ethylene copolymer consisting of 3 to 10 α-olefins In addition, it is possible to obtain a copied image having excellent rubbing image strength, excellent powder fluidity, no blocking phenomenon, and no damage by the peeling claw of the fixing roll portion. Further, when this magnetic toner is used, the toner carrier is less contaminated, and even if the formed toner image is repeatedly rubbed with the magnetic head during MICR reading, the toner image is less likely to peel off, the image quality is degraded, and It has the advantage that the read error rate is practically low as it does not cause dirt and contamination of the magnetic head, and therefore the magnetic toner of the present invention is particularly useful for magnetic reading by MICR. is there.

Claims (3)

[Claims] 1. A magnetic toner for MICR comprising a binder resin, a magnetic material and a lubricant as essential components, wherein the lubricant is an ethylene homopolymer obtained by polymerization in the presence of a metallocene catalyst or ethylene and C3. A polyethylene wax modified by graft-polymerizing a styrene-based monomer and / or an unsaturated carboxylic acid-based monomer onto an ethylene-based copolymer consisting of α-olefin of 10 to 10 and remaining toner particles A magnetic toner for MICR, which has a magnetization σ _rm of 4 to 7 emu / g. 2. The modified polyethylene wax has a density of 0.95 g / cm ³ or more and an average molecular weight of 800 to 300.
0, molecular weight distribution Mw (weight average molecular weight) / Mn (number average molecular weight) 1.1 to 1.8 ethylene homopolymer or ethylene copolymer 70 to 95 parts by weight, styrene monomer and / A polyethylene wax having a melt viscosity at 160 ° C. of 15 to 250 cps and a penetration of 2 dmm or less, which is modified by graft-polymerizing 5 to 30 parts by weight of an acrylic monomer.
A magnetic toner for MICR according to item 1. 3. A step of forming a latent image on a latent image carrier, a step of developing the latent image with a developer, a step of transferring the developed toner image to a transfer body, and a toner on the transfer body. An image forming method having a fixing step of heating and fixing an image, wherein the magnetic toner for MICR according to claim 1 is used as the developer.