JPH07230180A - Magnetic one component toner for forming micr image - Google Patents

Abstract

PURPOSE:To provide a toner for MICR excellent in fixing property at a low temp., small in the contamination of a carrier, free from the stripping of a toner image in repeating slide friction with a magnetic head at the time of magnetic reading, minimized in the degradation of picture quality, picture staining and the stain of a magnetic head and practically low in the rate of reading error. CONSTITUTION:In the magnetic one component toner for forming MICR image containing a magnetic body and a binder resin, the binder resin is a polyester resin and contains 1-10wt.% polyolefin having 0.01-0.5mum average dispersion diameter and the residual magnetization of the toner is 4.0-7.0emu/g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an electrostatic copying MICR.
(Magnetic image character recognition) The present invention relates to a magnetic one-component toner used in an image forming system. More specifically, the present invention relates to a magnetic one-component toner for magnetic image formation, in which a toner image fixed after printing can be read by a magnetic head or the like and there is no problem in repeated reading.

[0002]

2. Description of the Related Art At present, as a dry developing method in the electrostatic developing method which has been put into practical use, a two-component developing method using a carrier such as toner and iron powder, and a magnetic substance contained inside the toner without using a carrier. A one-component developing method using a magnetic toner is known. The one-component development method does not require an automatic density adjuster or the like, which is necessary for a two-component development method developing machine, so it will be used not only for small copying machines and printers, but also for medium-speed copying machines and above. Further improvement in performance is expected. By the way, attempts have been made to very easily prepare and print a document suitable for magnetic image character recognition, especially a personal check, by utilizing such a one-component magnetic toner developing system. Such a system is MIC
R (Magnetic Ink Character)
It is called a Recognization system. MICR is a method of magnetizing an image and reading it with a magnetic head. Usually, printing is performed using liquid magnetic ink and the image is read, so image formation is complicated. In that respect, the one-component magnetic toner development system is
Since the apparatus is compact and maintenance is easy, image formation can be performed very efficiently. However, the conventional one-component developing method has a problem that the magnetic toner forming an image is too weakly magnetized to be correctly recognized by a MICR reader.

The current MICR reader is designed on the premise that it reads liquid-printed images. On the other hand, magnetic toner does not soak into a fixed image carrier such as paper, The image is fixed on the surface of the fixed image carrier by heat fusion. Therefore, there is a problem in reading such that the formed magnetic toner image is easily peeled off from the paper as the image carrier, and the peeled toner contaminates the magnetic head. By the way, the magnetic toner applicable also to MICR needs to have both MICR aptitude and printer aptitude. That is, the MICR suitability that does not cause a problem due to repeated rubbing with the magnetic head, the suitability for the conventional electrophotographic system, and the printer suitability that the image quality is equal to or higher than that of the conventional electrophotographic printer. Strict conditions that must be possessed are required.

Therefore, as a method of obtaining an appropriate magnetization that can be read by a magnetic head, as compared with the conventional magnetic toner,
A method has been proposed in which the amount of toner developed per image is increased to enhance the magnetization of a toner image so that the toner image can be read. However, in this case, even if the magnetization is sufficient, there is a problem that the symbol cannot be correctly recognized because the image is crushed due to an excessive amount of toner and blurring (scattering of toner) occurs. . Further, a method of increasing the magnetic content itself of the toner particles to enhance the magnetic force of the toner image has also been proposed, but in this case, the tribo decreases, so that the sharpness of the image, especially in high temperature and high humidity, Since the image density is lowered, the durability stability is lowered, and the fixing property is also lowered, the image is easily scraped off by the MICR reader and the symbol cannot be recognized. As described above, the method of simply increasing the magnetization of the magnetic toner by increasing the developing amount of toner per image or increasing the magnetic substance content of the toner particles has many problems and is an effective method. Not really.

On the other hand, in Japanese Unexamined Patent Publication No. 4-166850, a magnetic substance content of 50 is used as an MICR toner.
% Or less, coercive force of 145 to 200 Oe, residual magnetization of 3.0 to
A magnetic toner of 5.5 emu / g has been proposed. This magnetic toner is effective in terms of magnetic force, but actually M
When it is used for ICR, image stain (smear) due to repeated rubbing with the magnetic head, magnetic head dirt (foil contamination), and read error rate (reject trait) increase, which is a practical problem. In particular, if a needle-shaped magnetic material having a high magnetic force is simply used as the magnetic material in order to increase the magnetic force, the bulk density will be significantly reduced, and the dispersibility will be poor. It becomes a problem. Further, various methods have been proposed for improving toner peeling in a MICR reader and contamination of a magnetic head by the toner. For example, in order to save resources in recent years, a double-sided copying machine has been installed in a copying machine of a medium speed class or higher,
To obtain double-sided copy, increase the slipperiness of the toner image surface,
In order to improve the 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. In this case, it is true that the addition of polyolefin is effective for improving the smudge property, but when the same fixed image is repeatedly rubbed as in the MICR system, the rubbing resistance is still not sufficient for practical use. Absent. Further, if the addition amount of this polyolefin is increased more than the conventional one, improvement of rubbing resistance can be expected, but since the polyolefin is hardly compatible with the toner, the dispersibility is poor, and the released polyolefin is carried on the toner. Contaminates the body and causes a decrease in image density. Therefore, a method has been proposed in which the dispersibility of the polyolefin is improved to improve the fluidity of the toner, the image quality, and the like. JP-A-2-251968 discloses an incompatible substance, for example,
A method of dispersing a polyolefin or the like with a maximum particle size of 5 μm or less is disclosed. According to this method, the image quality is initially improved, but in the long term, the amount of wax on the toner surface increases, and the charge amount decreases, so that fog occurs. Also,
There is a problem that adhesion to the magnetic roll also occurs.

[0006]

As described above, the toner containing a large amount of polyolefin to a certain extent has a surface structure different from that of the toner which is usually used. In the above long-term use, the image density tends to decrease due to the contamination of the toner carrier with the toner component, and particularly in the MICR system, the magnetic strength of MICR characters to be read cannot be sufficiently obtained. The present invention has been made for the purpose of solving the above problems.
That is, the object of the present invention is to provide an MICR satisfying the following requirements.
To provide a magnetic one-component toner (hereinafter referred to as "MICR toner") for use. (1) Appropriate magnetic force and accurate recognition of magnetically read symbols by MICR. (2) During magnetic reading, the toner image is not peeled off even when repeatedly rubbing against the magnetic head, and it is possible to suppress deterioration of image quality, image smearing, and magnetic head contamination. (3) The reading error rate (reject rate) by the MICR reader can be suppressed to a sufficiently low level for practical use. (4) The toner carrier is less contaminated and can be stably used for a long period of time, especially in medium- and high-speed machines. (5) The image density is high, and background stains, blurring, etc. can be suppressed to a low level. (6) Excellent fixability can be obtained even at a relatively low fixing temperature.

[0007]

Means for Solving the Problems The present inventors
As for the magnetic toner having both suitability and printer suitability, as a result of diligent study, a polyester resin was used as the binder resin, the residual magnetization of the magnetic toner and the content of the polyolefin in the magnetic toner were set to specific values, and, It has been found that the above object can be achieved by setting the average dispersed diameter of polyolefin within a very small specific range, and the present invention has been completed. The MICR image forming magnetic one-component toner of the present invention contains a magnetic material and a binder resin, wherein the binder resin is a polyester resin, and the average dispersion diameter of 0.01 to 1 to 10% by weight of 0.5 μm polyolefin is contained, and the residual magnetization of the toner is 4.0 emu / g to 7.0 emu / g.

The MICR toner of the present invention will be described in detail below. The MICR toner of the present invention is composed of a composition comprising a magnetic material, a binder resin and a polyolefin. The magnetic substance contained in the toner particles in the present invention may be any known magnetic substance that has been generally used in the past, but needle magnetic substances and doped magnetic substances are preferable. In addition, a 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, and then heat-reduced in a hydrogen atmosphere at 300 ° C. for 200 minutes, and after cooling. The product obtained by crushing is preferable because it has excellent environmental stability. In the present invention, the residual magnetization σrm of the magnetic substance contained in the toner particles is 7 to 24 em.
It is preferably in the range of u / g, more preferably 7 to
16 emu / g, particularly preferably 8-14 emu / g
Is the range. The remanent magnetization σrm of the magnetic material is 7 emu /
If it is less than g, the magnetization is weak and the symbol cannot be accurately recognized. If it exceeds 24 emu / g, the magnetization is too strong to recognize the symbol accurately.
The content of the magnetic material is preferably in the range of 20 to 80% by weight. The preferred range is 30 to 70% by weight
And a more preferable range is 40 to 60% by weight. When the content of the magnetic substance is less than 20% by weight, it is difficult to control the charge amount, and especially under a low temperature and low humidity environment, image density is reduced or uneven development occurs, and the MICR reader accurately recognizes the symbol. Can't do it.
On the other hand, if the content of the magnetic material exceeds 80% by weight, the magnetization of the toner becomes too large, making it difficult to develop with a normal developing system, and a sufficient image density cannot be obtained. On the other hand, if the content of the magnetic material is too large, the fixing property of the toner deteriorates, and M
In the ICR reader, the image is rubbed off or the magnetic material is peeled off, which makes it impossible to accurately recognize the symbol.

As the binder resin contained in the toner particles, a polyester resin is used from the viewpoint of low temperature fixability. The polyester resin used in the present invention has, as acid components, aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, trimellitic acid, pyromellitic acid, and benzophenonetetracarboxylic acid, diphenyl-p, p'-. Dicarboxylic acids, diphenylpolycarboxylic acids such as diphenylmethane-p, p'-dicarboxylic acid, aromatic oxycarboxylic acids such as p- (2-hydroxyethoxy) benzoic acid, succinic acid, fumaric acid,
Adipic acid, azelaic acid, sebacic acid, decamethylenedicarboxylic acid, 1,2,4-butyltricarboxylic acid,
Aliphatic polycarboxylic acids such as 1,2,5-hexanetricarboxylic acid and 1,3-dicarboxy-2-methylenecarboxypropane, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, cyclohexanetricarboxylic acid, Examples thereof include alicyclic polycarboxylic acids such as hexahydrophthalic acid and tetrahydrophthalic acid, and their anhydrides and derivatives. As the alcohol component, ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolethane , Trimethylolpropane, pentaerythritol, 1,2,3,6-hexanetetraol, dipentaerythritol, tripentaerythritol, 2-methylpropanetriol, 2-methyl-1,
Aliphatic polyols such as 2,4-butanetriol,
Alicyclic polyols such as 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, 1,3,5
-Aromatic polyols such as trihydroxymethylbenzene, ethylene oxide or propylene oxide adducts of bisphenol A, sorbitol, sorbitans such as 1,4-sorbitan, and the like can be used. By using the polyester resin as described above, low-temperature fixing becomes possible, and due to the polar group of the polyester resin,
The fixing strength can be increased. Further, it also has resistance to peeling of the magnetic powder.

Further, as the polyolefin to be contained in the toner particles, conventionally generally known materials can be used, for example, low molecular weight polyethylene, low molecular weight polypropylene, microcrystalline wax, various modified waxes, carnauba wax and the like. Of these, polyethylene is most preferred. In the present invention, when polyethylene wax is used as the polyolefin, MICR
It is optimal because it exhibits excellent rubbing resistance in the system. The content of polyolefin is 1 to 10 in the toner.
It must be in the range of weight percent, preferably 1
-8% by weight, more preferably 1-5% by weight. If the amount added is less than 1% by weight, rubbing resistance cannot be exhibited, and if it is more than 10% by weight, the developability deteriorates.

The average dispersed particle size of the polyolefin must be in the range of 0.01 to 0.5 μm, preferably 0.01 to 0.3 μm, more preferably 0.02 to 0. It is in the range of 2 μm. If the average particle size is smaller than 0.01 μm, sufficient rubbing resistance cannot be exhibited, and if it is larger than 0.5 μm, the toner carrier is contaminated and the developability deteriorates. The average dispersed particle diameter of the polyolefin is within the range of 0.01 to 0.5 μm, and the number of coarse dispersed particles or free polyolefin particles exceeding 2 μm is preferably 5% or less, more preferably 3% by number. The following, particularly preferably 1
The number is less than or equal to%. The dispersed particle size of the polyolefin is 0.3 for the toner particles with a cutter such as a microtome.
It can be determined by cutting into a thickness of about μm, taking a 9000 times photograph with a transmission electron microscope, randomly selecting about 100 polyolefin-dispersed particles, performing an analysis with an image analyzer and quantifying them.

In the magnetic toner of the present invention, since the binder resin itself has a negative charging property, it is not necessary to add a charge control agent, but if desired, for example, a fluorine-based surface active agent can be used. Agent, chromium-based dyes such as salicylic acid chromium complex,
A polymeric acid such as a copolymer containing maleic acid as a monomer component, a quaternary ammonium salt, an azine dye such as nigrosine, carbon black or the like can be added. Further, for the purpose of improving the durability, fluidity or cleaning property of the toner, inorganic fine powder such as silica, organic fine powder containing fatty acid or its derivative and metal salt, and fluorine resin fine powder are added. You can also

M of the present invention formed from the above constituents
In the ICR toner, the residual magnetization of the toner particles is 4 to 7e.
It is necessary to be in the range of mu / g, preferably 4.2 to 7 emu / g, and more preferably 4.5 to.
It is in the range of 6.5 emu / g. Remanent magnetization is 4 emu /
If it is less than g, the magnetization is weak and the symbol cannot be accurately recognized. If it exceeds 7 emu / g, the magnetization is too strong to recognize the symbol accurately. In the present invention, the strength of magnetization is VSM manufactured by Toei Industry Co., Ltd.
It is a value measured by a P-7 type with a measurement magnetic field of 5 kOe.

Next, a method for manufacturing the MICR toner of the present invention will be described. The MICR toner of the present invention can be applied by any method as long as the polyolefin can be dispersed in the toner in the form of fine particles. For example, a method of pulverizing a polyolefin in advance into a powder having a particle size of 10 μm or less and melt-kneading the powder with a magnetic material, a binder resin and other toner-forming components by a known kneading device such as an extruder, and adding water during the melt-kneading However, a method of suppressing an increase in temperature of the kneaded product so that the shearing force is sufficiently applied, and a method of adding a dispersion aid such as an oxidation wax or a polyethylene-ethylene oxide block copolymer can be used.

[0015]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited to these. Example 1 Using fumaric acid as an acid component and a propylene oxide adduct of bisphenol A as an alcohol component, a polyester resin (Mw = 15,000, Mn = 4,000,
Tg = 60 ° C.) was obtained. Next, using this polyester resin, powder-mixed with the following composition, set temperature 160 ℃
After kneading with an extruder, cooling, crushing,
Classification was performed to obtain a classified product having a 50% volume average diameter D50 of 9.5 μm (remanent magnetization of toner: 5.3 emu / g). Polyester resin 45% by weight Heat treated magnetite (residual magnetization 12.1 emu / g) 50% by weight Polyethylene wax 4% by weight Dispersion aid (polyethylene-ethylene oxide block 1% by weight copolymer) Classification obtained as described above 0.5% by weight of hydrophobic colloidal silica was added to the product, and the magnetic toner was obtained by stirring and mixing with a Henschel mixer.

Example 2 A magnetic toner was obtained in the same manner as in Example 1 except that the pulverized product was kneaded again, pulverized and classified without adding the dispersion aid. Comparative Example 1 In place of the heat-treated magnetite used in Example 1, magnetite with a residual magnetization of 7.8 emu / g was used.
A magnetic toner was obtained in the same manner as in Example 1. Comparative Example 2 A magnetic toner was obtained in the same manner as in Example 1 except that the dispersion aid was not added.

Comparative Example 3 Instead of the polyester resin of Example 1, styrene-n was used.
-Butyl acrylate copolymer (Mw = 130,00
0, Mn = 5,000, Tg = 60 ° C.) and a negative charge control agent (Bontron E-84, manufactured by Orient Chemical Co.) 1
A magnetic toner was obtained in the same manner as in Example 1 except that the weight% was added. Comparative Example 4 A magnetic toner was obtained in the same manner as in Example 1 except that the polyethylene wax of Example 1 was changed to 0.6% by weight.

The magnetic toners of the above Examples and Comparative Examples were
The MICR printer (4197 MICR printer, manufactured by Fuji Xerox Co., Ltd.) was supplied to a modified machine modified so that the set temperature of the fixing device was variable, and a printing test was performed. The MICR suitability test for images was performed as follows. (1) Signal strength Printing on check paper and measuring its magnetism
It was measured by Measure IV (XYTEC Corp.). If this value is 100 to 200%, it means that there is no reading error in the reader sorter of the reader of the actual MICR system.

(2) Leader sorter runnability About 500 sheets printed on check paper are actually read by a leader sorter (IBM-3890 MICR Reader).
Sorter) was evaluated 30 times. In this case, the following three evaluations were performed. (A) Image stains, and (b)
The head stain is caused by the rubbing property of the image and is considered to cause a reading error. (C) The read error rate is an actual error rate, and includes causes other than (a) and (b), for example, errors due to improper signal intensity. In Table 1, the rubbing property represents the evaluation result of (a) image stain and (b) head stain. (A) Image smear (smear) A phenomenon in which the area around the character part or the background is contaminated by the toner peeled off or scraped from the character part by rubbing. A rank sample for this phenomenon was created and evaluated. The evaluation criteria are as follows. ◯: Good, Δ: Practically possible limit, ×: Practically unusable. (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 head protection tape. A rank sample for this phenomenon was created and evaluated. The evaluation criteria are as follows.
◯: Good, Δ: Practically possible limit, ×: Practically unusable.

(C) Read Error Rate (Reject Rate = R.R.) When read by the reader sorter, those that cannot be read are automatically excluded as errors, and the error rate at that time is expressed as follows. . R. R. = (Excluded number of sheets / total number of passed sheets) × 100 Here, ◯ means 0.5% or less, Δ exceeds 0.5%, less than 1%, x: 1% or more. (3) Image Density (SAD) The reflection density of the solid portion of the image was measured by an X-rite device. (4) Fixing property The fixing temperature of the above modified machine was changed, and the fixing roll temperature when the fixing degree reached a practical level was evaluated as the minimum fixing temperature.

The evaluation results are summarized in Table 1.

[Table 1]

[0022]

Since the MICR toner of the present invention has the above-mentioned constitution, it has good fixability, little contamination of the toner carrier, and image density even when it is used for a long time exceeding 10,000 copies. It is possible to obtain a good image without reducing the value. Further, when magnetic reading is performed with a MICR reader, the toner image is less likely to be peeled off even when repeatedly rubbing against the magnetic head, image contamination and magnetic head contamination do not occur, and the reading error rate is high. The effect is that it is sufficiently low for practical use.

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Claims (3)

[Claims] 1. A MIC containing a magnetic material and a binder resin.
In the magnetic one-component toner for R image formation, the binder resin is a polyester resin, and the binder resin contains 1 to 10% by weight of a polyolefin having an average dispersion diameter of 0.01 to 0.5 μm. Has a residual magnetization of 4.0 emu / g
The magnetic one-component toner for MICR image formation, wherein the magnetic one-component toner has a content of ˜7.0 emu / g. 2. A magnetic one-component toner for MICR image formation, wherein the polyolefin is polyethylene. 3. A magnetic one-component toner for MICR image formation, wherein the polarity of the toner is a negative charging property.