JP2008080638A - Written trace eliminating method, and written trace eliminating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and its apparatus for eliminating a written trace having been written by a writing utensil in order to reuse a recording medium (especially paper). <P>SOLUTION: By this written trace eliminating method, the written trace which has been written with an ink on the surface of the recording medium layer is eliminated by exposing the written trace to an oxidized gas which is generated by a creeping discharge or a corona discharge. In this case, the recording medium has a base material and the layer which is formed at least on one surface of the base material, and contains an inorganic pigment, a binder and a cationic polymer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for erasing handwriting written on a recording medium (especially paper) and an apparatus for carrying out the method.

  As a method of reclaiming and reusing paper, a method is widely known in which printed paper is deinked, then fiberized, and re-made to make paper. Furthermore, recently, a method has been proposed in which an image is erased from a printed material on which an image is formed by a copying machine, a printer, or the like, and the paper from which the image is erased is reused. For example, in Patent Document 1 (Japanese Patent Application Laid-Open No. 7-253736), a gaseous chemically active substance that decomposes a developer substance is brought into contact with an image forming surface on a recording paper on which an image by the developer is formed. Accordingly, a recording paper reproduction method for erasing an image on the recording paper and reproducing the recording paper has been proposed. The developer is a toner, and the gaseous chemical active substance is obtained by activating a raw material gas having an organic substance decomposable element such as oxygen, fluorine, or chlorine.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2004-291638), an image of a printed matter having an image on the surface of a recording medium having a surface containing an inorganic pigment is generated by creeping discharge or corona discharge. A method of erasing an image by exposing to an oxidizing gas is proposed. The inorganic pigment is alumina or silica, and the image includes, for example, microbial dyes or dyes extracted from animals or plants, and is formed by, for example, ink jet recording.

JP-A-7-253736 JP 2004-291638 A

  As proposed in Patent Documents 1 and 2, various methods for erasing an image formed by a copying machine, a printer, and the like have been proposed so far, and recording paper and ink therefor have also been proposed. . However, the above document does not specifically propose a method for erasing handwriting by a writing instrument. Patent Document 2 only mentions that a stationery having a shape such as a pen may be used for printing / printing on a recording medium.

It is also beneficial from the viewpoint of paper reuse to erase handwriting by writing instruments. For example, at conferences and lectures, many materials are distributed to attendees in paper form, and attendees often write notes in the materials to organize their understanding. Therefore, after collecting the materials after the meeting is over, if you want to reuse the materials at another meeting, or if you want to reuse the materials on a blank page, you need to erase the handwritten handwriting. Arise.
This invention is made | formed in view of this situation, and it aims at providing the method and apparatus which erases the handwriting by a writing instrument using specific paper and a writing instrument.

  As a result of repeated investigations by the present inventors to achieve the above object, the handwriting written with a writing instrument on the surface of the recording medium having a layer containing a specific substance is relatively easy due to the oxidizing gas. It was found that the color disappeared or the color faded, and the present invention was devised. That is, the present invention provides a handwriting written with a writing tool on the surface of a recording medium having a base material and a layer containing an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the base material. The present invention provides a method for erasing handwriting on the surface of a recording medium including exposure to an oxidizing gas (hereinafter simply referred to as “handwriting erasing method”).

  Here, “erasing the handwriting” includes making it impossible to visually recognize the handwriting written on the recording medium and making the handwriting thin. The handwriting refers to a written diagram and fill.

  In the method of the present invention, a surface of a recording medium having a layer containing a substrate and an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the substrate (hereinafter, this surface is referred to as “writing”). It is characterized in that a handwriting is formed by writing on the surface). This layer makes it easier to erase the handwriting formed on the surface when exposed to oxidizing gas.

  The cationic polymer contained in the layer that gives the writing surface is preferably an amine polymer. The amine-based polymer is preferably a repeating unit having a quaternary ammonium salt.

  The writing instrument used in the handwriting erasing method of the present invention is preferably a writing instrument using an ink composition containing at least one dye selected from an anthraquinone dye and a methine dye as a pigment. Handwriting written on the writing surface with ink containing these dyes is easily erased by oxidizing gas.

  The generation of the oxidizing gas is preferably performed between the first electrode and the second electrode separated by a dielectric having a surface for creeping discharge in an atmosphere of a gas capable of generating an oxidizing gas by discharge. It includes generating creeping discharge from the surface for creeping discharge by applying a voltage therebetween.

  Alternatively, the generation of the oxidizing gas is preferably performed by applying a negative voltage to the second electrode with respect to the grounded first electrode in a gas atmosphere capable of generating an oxidizing gas by discharge. And corona discharge between these electrodes.

The present invention also provides a handwriting written on a surface of a recording medium having a base material and a layer containing an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the base material with a writing tool, An erasing device,
(A) an oxidizing gas generating means, and (b) a placing portion on which the written recording medium is placed, and the oxidizing gas generating means and the placing portion are such that the written recording medium is exposed to the oxidizing gas. A handwriting erasing device arranged to be provided. This erasing device is used for carrying out the handwriting erasing method of the present invention.

In the handwriting erasing apparatus of the present invention, the oxidizing gas generating means,
Having a first electrode, a second electrode, and a dielectric separating these electrodes;
The dielectric has a surface that generates creeping discharge by applying a voltage between these electrodes.
A creeping discharge generating means is preferable.

Alternatively, the oxidizing gas generating means is
Having a first electrode and a second electrode;
Corona discharge is generated by applying a negative voltage to the second electrode with respect to the grounded first electrode.
It is preferably a corona discharge generating means.

The present invention also provides
The handwriting erasing apparatus of the present invention,
A base material, a recording medium having a layer containing an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the base material, and an ink composition that can be erased by an oxidizing gas, as the ink, A handwriting erasing system including a writing instrument used for writing on a recording medium is provided. This system is used to implement the handwriting erasing method of the present invention.

  Furthermore, the present invention is an inorganic material used in the handwriting erasing method and handwriting erasing apparatus of the present invention, or formed on at least one surface of a base material as a recording medium constituting the handwriting erasing system. A recording medium having a layer comprising a pigment, a binder, and a cationic polymer is provided.

  Furthermore, the present invention provides a writing instrument that uses, as an ink, an ink composition containing at least one dye selected from an anthraquinone dye and a methine dye as a pigment as a writing instrument used for writing on the recording medium. .

  The present invention provides a method and apparatus that allows erasing handwritten handwriting. These methods and devices allow plain paper or printed matter to be returned to their pre-written state and reused without the need for deinking and refibration processes. Therefore, the present invention is preferably used from the viewpoint of environmental protection and resource saving, or is preferably used when it is desired to erase the handwriting for confidential reasons.

The handwriting erasing method and handwriting erasing apparatus of the present invention will be specifically described.
[recoding media]
The recording medium used in the method and apparatus of the present invention has a substrate and a layer containing an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the substrate. The method and apparatus of the present invention erases the handwriting written on the surface of this layer of the recording medium. Hereinafter, this layer is referred to as a “writing surface forming layer” for convenience. Hereinafter, the substance which comprises a writing surface formation layer is demonstrated.

  The inorganic pigment is preferably present in the writing surface forming layer in the form of particles having pores. Such an inorganic pigment is preferably a porous body. Specifically, inorganic pigments include alumina, silica, silica-alumina, colloidal silica, zeolite, clay, kaolin, talc, calcium carbonate, barium sulfate, aluminum hydroxide, titanium dioxide, zinc oxide, satin white, diatomaceous earth, and It is preferably at least one substance selected from the group consisting of acid clay. The inorganic pigment is more preferably alumina or silica, and even more preferably silica.

  The binder serves to fix the inorganic pigment and other substances contained in the writing surface forming layer to the substrate surface. The binder is preferably an aqueous binder. Here, “aqueous” means having the property of being dissolved in water or being well dispersed in water. Specific examples of the aqueous binder include polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), casein, styrene butadiene rubber, starch, polyacrylamide, polyvinyl pyrrolidone, polyvinyl methyl ether, and polyethylene oxide. Without being limited thereto, other aqueous binders (for example, water-soluble polymers) may optionally be used. These aqueous binders may be used alone or in combination of two or more.

  More preferably, polyvinyl alcohol (PVA) and ethylene vinyl acetate (EVA) are used in combination as the binder. When PVA and EVA are used in combination as a binder, the strength of the film can be synergistically improved, and the peel strength between the paper and the writing surface forming layer can be further increased. As PVA, for example, PVA-R1130, 117, and 117K manufactured by Kuraray Co., Ltd. can be used, and as EVA, for example, Sumikaflex S-401HQ, S-470HQ, S-500, S-500 manufactured by Sumitomo Chemical Co., Ltd. -752, and S-755 can be used. PVA and EVA are preferably contained in the writing surface forming layer in a mass ratio of 1/9 to 9/1.

  The writing surface forming layer further contains a cationic polymer. The cationic polymer refers to a polymer having a cationic group or a group that can be ionized to a cationic group. The cationic polymer is contained in the writing surface forming layer in order to ensure the erasability of the written handwriting.

  As the cationic polymer, an amine-based polymer is preferably used. The amine-based polymer is a polymer including a repeating unit having an amine. Specifically, examples of the amine-based polymer include a polymer including a repeating unit having a primary amine or a hydrochloride thereof, a secondary amine or a hydrochloride thereof, a tertiary amine or a hydrochloride thereof, or a quaternary ammonium salt. The cationic polymer may be a homopolymer containing one type of monomer as a repeating unit, or may be a copolymer containing two or more types of repeating units. The cationic polymer may also be one obtained by copolymerizing a repeating unit having the amine or its hydrochloride or quaternary ammonium salt with another repeating unit (for example, acrylamide).

  The amine-based polymer reduces the change over time in the erasability of handwriting written with a writing instrument. The erasability change with time means that the erasability of handwriting immediately after writing is different from the erasability of handwriting after several hours have passed since writing. Generally, handwriting erasability is time after writing. It tends to decrease as time passes. The amine-based polymer has a feature of reducing the change over time in the erasability of handwriting written on the writing surface forming layer containing the amine-based polymer. The cationic polymer generally has a role of stabilizing the handwriting before being erased, and improves the stability (for example, storage stability) of the handwriting itself.

Specifically, the amine-based polymer is, for example, acrylamide diallylamine hydrochloride copolymer (CAS No. 344447-60-4). Alternatively, the amine-based polymer is, for example, a polymer having a repeating unit of diallyldimethylammonium chloride having a quaternary ammonium salt represented by the following formula.

  As the acrylamide diallylamine hydrochloride co-product, for example, Sumirez Resin 1001 manufactured by Sumika Chemtex can be used. As the amine-based polymer containing a repeating unit having the quaternary ammonium salt, for example, Unisense FPA101 and FPA102 manufactured by Senka Co., Ltd. can be used, or PAS-H-1L, 5L manufactured by Nitto Boseki Co., Ltd. And 10L can be used. Alternatively, as the amine-based polymer, a PAA series (for example, PAA-01, PAA-03, PAA-05, PAA-08, PAA-15, PAA) manufactured by Nitto Boseki Co., Ltd., containing a repeating unit having a primary amine. -15B, PAA-10C, PAA-25, and PAA-H-10C).

  As the amine polymer, those containing a repeating unit having a quaternary ammonium salt are preferably used. When the writing surface forming layer contains a polymer containing a repeating unit having a quaternary ammonium salt, the erasability of handwriting by an ink composition having a specific pigment described later is particularly improved. Moreover, the polymer containing the repeating unit which has a quaternary ammonium salt reduces the time-dependent change of the erasability of the said handwriting compared with another amine polymer.

  The mixing ratio of the inorganic pigment, the binder, and the cationic polymer is appropriately selected so as to give a writable surface and allow the handwriting after writing to be erased by the oxidizing gas. Specifically, it is preferable that the binder is contained in the writing surface forming layer in an amount of 35 to 75 parts by mass and the cationic polymer in an amount of 5 to 20 parts by mass with respect to 100 parts by mass of the inorganic pigment.

  The writing surface forming layer is formed on at least one surface of the substrate and may be formed on both surfaces. A recording medium having a writing surface forming layer on both sides is preferable because both sides become surfaces capable of erasing the handwriting written thereon.

Writing surface forming layer, the ^substrate, which is preferably formed in an amount of about ^{0.1g / m 2 ~50g / m 2} . If the amount of the writing surface forming layer is small, the handwriting written on the layer may not be erased sufficiently. Even if the amount of the writing surface forming layer exceeds 50 g / m ² , the action of this layer is not changed, and it is not meaningful to provide a writing surface forming layer in an amount larger than this.

  The base material which forms a writing surface formation layer is not specifically limited, A sheet-like thing can be used arbitrarily. Specifically, the substrate may be paper, synthetic paper, a film made of plastic, a sheet or plate, a sheet or plate made of metal, or a sheet or plate made of glass. The substrate is preferably paper.

When the substrate is paper, the type of paper is not particularly limited as long as it can be reused after erasing the handwriting, and may be any of acidic paper, neutral paper, and alkaline paper. The paper used as a base material is manufactured by making paper by a conventional method using chemical pulp and fillers typified by LBKP and NBKP as main raw materials, and using other internal sizing agents and paper making aids as necessary. As the pulp material, mechanical pulp or recycled recycled paper may be used, or these may be used as the main raw material. As the filler, calcium carbonate, kaolin, talc, titanium dioxide and the like can be used. The paper as the base material may further contain a hydrophilic binder, a matting agent, a hardener, a surfactant, a polymer latex, a polymer mordant, and the like, or these may be applied to the paper. The basis weight of the paper serving as the substrate is preferably 40 to 700 g / m ² .

  The writing surface forming layer is prepared by dissolving and / or dispersing an inorganic pigment, a binder, and a cationic polymer in water to prepare a coating liquid, applying the coating liquid to the surface of the substrate, and then drying the coating liquid. Can be formed. The coating liquid contains a pigment dispersant, a water retention agent, a thickener, an antifoaming agent, a release agent, a colorant, a water-resistant agent, a wetting agent, a fluorescent dye, and an ultraviolet absorber as necessary. Good.

  The coating liquid is applied to the substrate surface by, for example, a roll coater method, a blade coater method, an air knife coater method, a gate roll coater method, a bar coater method, a spray coat method, a gravure coater method, a curtain coater method, or a comma coater method. It may be applied. After the application, for example, it is dried using a hot air drying furnace or a hot drum. In the case of using a thermal drum, the coating layer can be pressure-bonded to the heated finished surface and dried. In addition, the coating layer is an aqueous solution containing nitrate, sulfate, formate or acetate of zinc, calcium, barium, magnesium or aluminum for the purpose of solidifying the binder with respect to the wet coating layer before drying. May be processed.

  The coating solution is preferably prepared so as to contain 5 to 40% by mass of a component that becomes a solid content after drying. If the amount of solid content in the coating liquid is small, a uniform layer may not be formed after coating. Moreover, when there is much quantity of solid content, it will become difficult to perform application | coating operation | work. Further, even if the amount of solid content is increased and the layer after application is thickened, if the amount exceeds a certain amount, no significant improvement is observed in terms of erasing handwriting. The coating liquid with the solid content adjusted is applied by adjusting the coating amount so that a desired amount of solid content remains on the substrate (that is, a desired amount of writing surface forming layer is formed). Is done.

  The base material on which the writing surface forming layer is thus formed is used as a recording medium in the handwriting erasing method and the handwriting erasing apparatus of the present invention. In general, the recording medium is preferably supplied in the form of paper or roll paper cut into a predetermined size as printing or copying paper. This is because there are many requests for reuse of paper in such a form. Of course, the recording medium may be provided in other forms, for example, as various notebooks, memo paper, photographic paper, stickers, labels, compact discs, or courier slips. The recording medium may be pre-printed, for example, paper on which ruled lines or grids are printed, or predetermined information printed at a lecture or meeting is printed. It may be a document.

[Writing instruments]
The method and apparatus of the present invention erases the handwriting written on the recording medium with a writing instrument. The writing instrument is preferably in the form of a core-type writing instrument such as a marker and a sign pen, or a ballpoint pen, which allows ink to ooze from the pen tip, and more preferably a ballpoint pen. A ballpoint pen is a writing instrument in which an ink storage tube loaded with ink is provided in a shaft, and ink is drawn out from a pen tip on which a small sphere is attached. Since the ballpoint pen performs writing by exuding ink by the rotation of the ball, it has an advantage that powder such as an inorganic pigment is hardly generated on the writing surface containing the inorganic pigment. The center-type writing instrument has a center core in which the fiber bundle is converged as an ink containing portion, and a pen tip (tip) for discharging the ink stored in the center core. As the tip, for example, a ball, fiber, plastic A writing instrument provided in a core, a brush-like object, or a brush-like object.

  The writing instrument can be assembled using known members. For example, a ballpoint pen can be manufactured by loading ink into an ink containing tube formed of a known material and having a known size and assembling it with a known structure of a ballpoint pen tip of a known structure made of a known material. The ink storage tube is, for example, a synthetic resin pipe such as polyethylene and polypropylene, or a metal pipe. In addition, the core-type writing instrument can be prepared by preparing a core (ink containing portion) in which fiber bundles are converged, filling it with ink, and assembling it with a pen tip by a known assembly method.

  The ink of the writing instrument contains a pigment in any form. The dye is not particularly limited, and for example, an acid dye, a basic dye, and a direct dye can be used. The ink is preferably an ink composition containing at least one dye selected from anthraquinone dyes and methine dyes as a pigment. These dyes show good erasability when erasing handwriting by the method of the present invention. This ink is preferably used as a water-based ink containing water (or a water-soluble organic solvent) as a main solvent.

  The anthraquinone dye is not particularly limited as long as it has anthraquinone as a basic skeleton, and a known or commercially available one can be used. Specific examples of anthraquinone dyes include CI Acid Blue 25, CI Acid Blue 27, CI Acid Blue 40, CI Acid Blue 41, CI Acid Blue 43, CI Acid Blue 47, CI Acid Blue 53, CI Acid Blue 55 , CI Acid Blue 62, CI Acid Blue 78, CI Acid Blue 80, CI Acid Blue 124, CI Acid Blue 127, CI Acid Blue 129, CI Acid Blue 145, CI Acid Blue 150, CI Acid Blue 230, CI Acid Blue 277 , CI Basic Violet 34, CI Basic Violet 42, CI Basic Violet 43, CI Basic Violet 63, CI Acid Green 25, CI Acid Green 27, CI Acid Green 37, CI Acid Green 38, CI Acid Green 41, CI Acid Green 44 CI Acid Brown 26, Anthraquinone Green GX, Alizarin Direct Blue 6G, Alizarin Direct Green G, Ionamine Pure Blue G (CI 63605), Ionamine Pure Blue R (CI 63320), and Toluidine Blue.

  Here, the methine dye refers to a dye having a methine group, and thus a polymethine dye and a cyanine dye are also included in the methine dye. Known or commercially available methine dyes can be used. Specific examples of methine dyes include CI Basic Red 12, CI Basic Red 13, CI Basic Red 14, CI Basic Red 15, CI Basic Red 27, CI Basic Red 35, CI Basic Red 36, CI Basic Red 37 , CI Basic Red 45, CI Basic Red 48, CI Basic Yellow 11, CI Basic Yellow 12, CI Basic Yellow 13, CI Basic Yellow 14, CI Basic Yellow 21, CI Basic Yellow 22, CI Basic Yellow 23, CI Basic Yellow 24 , CI Basic Yellow 32, CI Basic Orange 21, CI Basic Orange 22, CI Basic Blue 62, CI Basic Blue 63, CI Basic Violet 7, CI Basic Violet 15, CI Basic Violet 16, CI Basic Violet 20, CI Basic Violet 21 , And CI Basic Violet 39.

  Among these dyes, an ink composition containing as a pigment at least one dye selected from C.I. Acid Blue 80, C.I. Acid Green 25 and C.I. Basic Violet 7 is more preferably used in the method of the present invention.

  The ink composition is preferably a gel ink composition. The writing instrument using a gel ink composition (hereinafter also referred to as “gel ink”) as an ink is preferably a ballpoint pen. The gel ink has a high viscosity in a normal state, and has a property that the viscosity becomes low when a force is applied (for example, when a shearing force is applied when the ball rotates in a ballpoint pen). This property of gel ink is advantageous for erasing handwriting. In other words, writing tools that use gel inks have a low viscosity due to the force applied during writing, which enables smooth writing. If this is used, clogging will occur even on the writing surface forming layer. You can write without Further, after writing, the gel ink tends to return to the original high viscosity state on the surface of the recording medium, and thus hardly penetrates into the writing surface forming layer. Therefore, the handwriting exists at a relatively shallow position on the surface, and is easily erased well when exposed to the oxidizing gas. Furthermore, the handwriting by gel ink is characterized in that it is well erased by the method and apparatus of the present invention even after several hours or more after writing, and the change in erasability with time is small.

  A gel ink is a composition in which a dye as a pigment, a water-soluble polymer, and other additives are dissolved or dispersed in water and / or an aqueous medium. The dye contained in the gel ink is not particularly limited, and for example, an acid dye, a basic dye, and a direct dye may be used. Preferably, one or more dyes selected from the anthraquinone dyes and methine dyes described above are used as the dye. More preferably, one or more dyes selected from C.I. Acid Blue 80, C.I. Acid Green 25 and C.I. Basic Violet 7 are used.

  In the gel ink, the dye is preferably contained in an amount of 0.05 to 15.0% by mass. When the amount of the dye is less than 0.05% by mass of the entire ink composition, it may be difficult to visually recognize the coloring by the dye. When the amount of the dye exceeds 15.0% by mass, it may be difficult to erase the handwriting even if the oxidizing gas is generated at an appropriate concentration. The dye is more preferably contained in the gel ink at a ratio of 0.1 to 10.0% by mass.

  The gel ink contains a water-soluble polymer, thereby having the above-described characteristic viscosity and thus improving the decoloring property. The water-soluble polymer is not particularly limited as long as it can increase the viscosity of the ink composition and / or impart adhesiveness to the ink composition. Examples of water-soluble polymers include microbial polysaccharides or derivatives thereof such as pullulan, xanthan gum, welan gum, and rhamzan gum; water-soluble plant polysaccharides or derivatives thereof such as guar gum, locust bean gum, and pectin. Gelatin, casein and the like which are water-soluble animal polysaccharides or derivatives thereof; cellulose derivatives such as sodium and ammonium salts of celluloses such as hydroxyethylcellulose, carboxymethylcellulose (CMC) and hydroxypropylcellulose; starch; Such as starch, cationic starch, dextrin, modified dextrin, sodium starch glycolate, etc .; vinyl synthetic polymers such as polyvinyl alcohol (PVA), polyvinyl Examples thereof include: Lidon, polyvinyl ether, etc .; acrylic synthetic polymer, sodium polyacrylate, carboxyvinyl polymer, etc .; other synthetic polymers, polyethylene oxide, methoxyethylene maleic acid copolymer, etc. . The gel ink may contain one or more water-soluble polymers selected from these.

  The content of the water-soluble polymer in the gel ink is appropriately determined according to the type of the water-soluble polymer, and is usually about 0.05 to 40% by mass, preferably about 0.1 to 30% by mass. If the content of the water-soluble polymer exceeds 40% by mass, writing may be difficult, and if it is less than 0.05% by mass, the effect of adding the water-soluble polymer may not be obtained. is there.

  The gel ink may contain a water-soluble organic solvent. The water-soluble organic solvent is added to prevent drying at the nib and to prevent the ink from freezing. Specifically, the water-soluble organic solvent includes, for example, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, and polyethylene glycol, polyhydric alcohols such as glycerin, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, And glycol ethers such as dipropylene glycol monomethyl ether and dipropylene glycol monopropyl ether. These organic solvents may be used alone or in combination of two or more. Preferably, a combination of propylene glycol and glycerin is used.

  The water-soluble organic solvent is preferably contained in the gel ink in an amount of 1.0 to 40.0% by mass. When the content of the water-soluble organic solvent is less than 1.0% by mass, the pen tip is easily dried and the ink is easily frozen. When the content of the water-soluble organic solvent exceeds 40.0% by mass, the solubility of the water-soluble polymer is affected, and the handwriting or the coating film formed from the gel ink is difficult to dry. The more preferable content of the water-soluble organic solvent varies depending on the type, but is generally 5.0 to 30.0% by mass.

  You may mix | blend another additive with a gel ink in the range which does not prevent the effect. For example, polyoxyethylene alkali metal salt, dicarboxylic acid amide, phosphate ester, or N-oleyl sarcosine salt may be added as a lubricant, and polyhydric alcohol or a derivative thereof (such as glycerin) is added as a wetting agent. You may add benzotriazole, tolyltriazole, or dicyclohexylammonium nitrate as a rust inhibitor, and add benzoisothiazoline compounds, pentachlorophenol compounds, cresol, etc. as antiseptic / rust inhibitors. As a fungicide, methyl paraoxybenzoate and Amorden HS (trade name, manufactured by Daiwa Chemical Industry Co., Ltd.) may be added. In addition, various dispersants and surfactants may be added.

  The gel ink can be prepared using a known stirring method, defoaming method, filtration method and the like. For example, after mixing and stirring water and a water-soluble dye, a water-soluble polymer is blended, and then a water-soluble organic solvent and various additives as necessary are blended to obtain a gel ink. The mixing or stirring in each step can be performed using a known stirring device such as a dissolver.

  The gel ink preferably has a viscosity of 100 mPa · s to 10000 mPa · s before writing. Here, the viscosity of the gel ink is shown as a value measured using an ELD viscometer under the condition of 3 ° (R14) cone rotation speed 0.5 rpm (20 ° C.). By setting the viscosity within this range, a writing instrument having excellent erasability and writing ability can be provided, for example, in the form of a ballpoint pen. The viscosity can be adjusted with a water-soluble polymer and water.

  Although the gel ink has been described above, the handwriting erased by the method and apparatus of the present invention may be written with another ink. For example, when the writing instrument is a core writing instrument, it is preferable to use a water-based ink composition having a viscosity of 2.0 mPa · s to 10 mPa · s. Here, the viscosity within this range is shown as a value measured using an ELD viscometer under the condition of 1 ° 34 '(R24) cone rotation speed 0.5 rpm (20 ° C). When the viscosity of the ink used for the core-type writing instrument is less than 2.0 mPa · s, the dye dispersion stability deteriorates, and problems such as ink drop, handwriting density, and ink leakage occur. On the other hand, when it exceeds 10 mPa · s, the outflow of ink becomes worse. The viscosity of the ink can be adjusted within this range by adjusting the amount of dye, water-soluble polymer and water-soluble organic solvent used, or by using an activator or other additives.

  A water-based ink composition suitable for a core-type writing instrument is obtained by dissolving or dispersing the dye, water-soluble organic solvent, and additive described in relation to the gel composition in water and / or an aqueous medium. It can be prepared in such a way that a viscosity is obtained. It is preferable that 0.1-7 mass% of dye is contained with respect to the composition whole quantity, for example. The disadvantages that can occur if the proportion of dye is too small or too large are as described above for the gel ink composition. It is preferable that 10-30 mass% of water-soluble organic solvents are contained with respect to the composition whole quantity, for example. If the ratio of the water-soluble organic solvent is too small, writing blur may occur, and if it is too large, the drying property of the handwriting is deteriorated and the water resistance is weakened. The water-soluble polymer is added as necessary, and may not be added when a desired viscosity is obtained.

[Generation of oxidizing gas]
In the method and apparatus of the present invention, the handwriting written on the specific recording medium is erased by exposure to an oxidizing gas. The oxidizing gas is preferably, for example, an ionization / dissociation gas and its secondary product. The secondary product is preferably at least one selected from the group consisting of ozone, hydroxy radicals, carbonate ions and nitrogen oxides. In particular, ozone is preferable because the bond is rapidly cleaved after the electrophilic addition reaction to the alkene. These oxidizing gases are generated by performing creeping discharge or corona discharge in an atmosphere of gas that can generate oxidizing gas by discharge. Gases that can generate an oxidizing gas include air, oxygen, nitrogen, carbon dioxide, and water vapor. These gases can be used in combination of two or more. Hereinafter, creeping discharge and corona discharge performed in an air atmosphere will be described.

(Creepage discharge)
In creeping discharge, an alternating voltage is applied between a pair of electrodes separated by a dielectric, thereby generating a discharge along the dielectric and generating an oxidizing gas. In this case, the recording medium on which the handwriting is written (hereinafter, this recording medium is referred to as a written medium for convenience) is placed on the mounting portion in the vicinity of the discharge region of the creeping discharge, and the oxidizing gas. Expose to. The placement unit may be used for running the written medium, or may be for keeping the written medium stationary. When the written medium is run, it is preferable to use at least one type of conveying means selected from the group consisting of endless belt conveyance, roll conveyance, and drum conveyance as the placement unit. Further, the written medium may be run only in a certain direction or may be reciprocated. Or you may combine driving | running | working of a fixed direction and reciprocating driving | running | working.

  FIG. 1 is a schematic side view showing an embodiment of an apparatus according to the present invention for erasing handwriting from a written medium. FIG. 1 shows an example in which an oxidizing gas is generated by applying an alternating voltage to a creeping discharge electrode.

  In FIG. 1, an electrode 3 for generating creeping discharge includes a pair of electrodes 31 and 32 that are separated by a dielectric 33 and face each other. In FIG. 1, one electrode 31 is embedded in a dielectric 33, and the other electrode 32 is provided on the bottom surface of the dielectric 33. Oxidizing gas is generated in the discharge region 34 in the vicinity of the electrode 32 below the bottom surface of the dielectric 33. In FIG. 1, reference numeral 2 denotes an AC power source.

  The shape of the electrodes 31 and 32 is not particularly limited. For example, the electrode 31 embedded in the dielectric 33 may have a plate shape, and the electrode 32 positioned on the bottom surface of the dielectric 33 may have a wire shape. Examples of the material constituting the electrodes 31 and 32 include metals such as Al, Cr, Au, Ni, Ti, W, Te, Mo, Fe, Co, and Pt. The electrodes 31 and 32 may be formed of an alloy containing one or more metals selected from these metals, or may be formed of an oxide of one or more metals selected from these metals. Good.

  The distance between the electrode 31 and the electrode 32 is preferably 1 μm or more, and more preferably 3 to 200 μm. The alternating voltage (Vpp) applied to the creeping discharge electrode 3 is preferably 1 to 20 kV, and the frequency is preferably 100 Hz to 5 MHz. In particular, when Vpp is 1 to 10 kV and the frequency is 1 kHz to 2 MHz, it is preferable because the handwriting can be erased more efficiently. In this case, the distance between the electrode 32 and the written medium 1 is preferably 100 mm or less (including a distance of 0 mm when the medium and the electrode are in contact).

  The dielectric 33 is made of a material that can form a surface that can cause creeping discharge. Such a material is, for example, ceramic or glass. Specific examples of the ceramic and glass constituting the dielectric 33 include metal oxides such as silica, magnesia and alumina, and nitrides such as silicone nitride and aluminum nitride.

  When the written medium 1 is exposed to the oxidizing gas, the written medium 1 may be stationary with respect to the discharge region 34, or may be moved relatively, depending on the purpose, either stationary or moving. select. FIG. 1 shows an example in which the written medium 1 is transported using the conductive endless belt 5 rotated by a roll 53 as a mounting portion in the vicinity of a discharge region 34 for creeping discharge. By disposing the conductive endless belt 5 so as to pass near or inside the discharge region 34, the discharge region 34 is spread between the bottom surface of the dielectric 33 and the conductive endless belt 5, and the written medium 1 and the oxidized region are oxidized. The contact efficiency with the property gas is improved. For this reason, it is preferable to ground the conductive endless belt 5 as shown in FIG. 1 or to apply a positive or negative voltage. The conveyance speed depends on Vpp, frequency, and also the distance between the electrode 32 and the written medium 1, but is, for example, 2000 cm / min or less if Vpp, frequency, and distance are within the aforementioned ranges. In particular, when the speed is 500 cm / min or less, the handwriting can be erased more efficiently.

  A transport means for placing and transporting the written medium 1 is not particularly limited, and a known means can be used. In addition to endless belt conveyance, for example, roll conveyance, drum conveyance, and the like can be given. As described above, the conveying means is preferably made of a conductive material, but is not limited to this, and can be made of a non-conductive material if necessary. The conductive material that can constitute the transport means is as described for the electrodes 31 and 32.

  Exposure of the written medium 1 to the oxidizing gas may be performed in a closed system or an open system, and either system can be selected according to the purpose. However, it is preferable to expose the written medium 1 to the oxidizing gas in a closed system so that the oxidizing gas does not leak from the handwriting erasing apparatus. The handwriting erasing device is preferably provided with an adsorption filter or the like for preventing leakage of oxidizing gas.

  FIG. 2 is a schematic side view showing another example of an apparatus for erasing handwriting by creeping discharge. In FIG. 2, the same members or parts as those in the apparatus shown in FIG. The creeping discharge electrode 3 shown in FIG. 2 shows an example in which a pair of electrodes 31 and 32 facing each other are both embedded in a dielectric 33. In this case, the oxidizing gas is generated in a portion corresponding to the end portion of the electrode 32 on the bottom surface of the dielectric 33 (portion shown as the discharge region 34 in FIG. 2).

  In the example shown in FIG. 2, the first bias electrode 6 and the power source 21 that applies a DC bias voltage to the first bias electrode 6 are provided on the bottom surface of the dielectric 33. By applying a bias voltage between the first bias electrode 6 and the conductive endless belt 51 also serving as the second bias electrode, the oxidizing gas moves from the generation site toward the written medium 1. Therefore, the contact efficiency between the medium 1 and the oxidizing gas is improved. In general, the bias voltage is preferably 0.2 to 4.0 kV. The materials that can constitute the first bias electrode 6 are as described for the electrodes 31 and 32.

  FIG. 3 is a schematic side view showing another embodiment of an apparatus for erasing handwriting by creeping discharge. In FIG. 3, the same members or parts as those in the apparatus shown in FIG. The creeping discharge electrode shown in FIG. 3 shows an example in which a pair of electrodes 31 and 32 are embedded in the dielectric 33 so that they are arranged on a plane parallel to the bottom surface of the dielectric 33. In this case, the oxidizing gas is generated around the vicinity of the electrodes 31, 32 below the dielectric bottom surface (portion shown as the discharge region 34 in FIG. 3). If necessary, a configuration may be adopted in which three electrodes are embedded so as to be arranged on a plane parallel to the bottom surface of the dielectric 33 (not shown).

  FIG. 6 is a schematic side view showing another embodiment of an apparatus for erasing handwriting by creeping discharge. In FIG. 6, the same members or parts as those in the apparatus shown in FIG. In the creeping discharge generator, the dielectric layer 33 may be provided on one or both of the electrodes 31 and 32. In the example shown in FIG. 6, both the electrodes 31 and 32 are formed in a plate shape, and a dielectric 33 is formed on the electrode 31. The written medium 1 is not placed between the electrode 31 and the opposing electrode 32, but is placed in a sealed container 42 that covers the electrode 31, the dielectric 33, and the plate-like counter electrode 32. The dielectric 33 can be composed of the materials described above in connection with FIG.

(Corona discharge)
In corona discharge, a voltage is applied between the discharge electrode and the counter electrode facing the discharge electrode to generate a discharge and generate an oxidizing gas. The voltage applied to the discharge electrode may be either an AC voltage or a DC voltage. When a DC voltage is applied, the polarity is preferably negative. Further, an AC voltage may be superimposed on the DC voltage.

  The discharge is preferably generated with the counter electrode grounded. The discharge electrode may have any of a wire shape, a roll shape, a blade shape, a plate shape, a brush shape, a needle shape, and a bar shape. In the corona discharge, it is preferable to contact the counter electrode and at least a part of the written medium. The written medium is placed on the mounting portion and exposed to the oxidizing gas in the discharge space between the discharge electrode and the counter electrode. The placement unit may be used for running the written medium, or may be for keeping the written medium stationary. When the written medium is run, it is preferable to use at least one type of conveying means selected from the group consisting of endless belt conveyance, roll conveyance, and drum conveyance as the placement unit. It is preferable that the transport means is also conductive and thus functions as a counter electrode. The written medium may be run only in a certain direction or may be reciprocated. Alternatively, traveling in a certain direction and reciprocating traveling may be combined.

  FIG. 4 is a schematic side view showing an example of an apparatus according to the present invention for erasing handwriting from a written recording medium by corona discharge. 4, the same members or parts as those in the apparatus shown in FIG. Generally, corona discharge is generated by providing a discharge electrode and a counter electrode at a position opposite to the discharge electrode and applying a voltage to the discharge electrode. In the apparatus shown in FIG. 4, the discharge electrode 4 is formed in a wire shape, and the conductive endless belt 52 serving as a placement portion for a written medium functions as a counter electrode. As shown in FIG. 4, it is preferable to ground the conductive endless belt 52 in order to efficiently generate the ionized / dissociated gas and its secondary product by corona discharge. In FIG. 4, reference numeral 22 denotes a DC voltage applying means, and 41 denotes a cover that covers the discharge electrode 4.

  The applied voltage may be a DC voltage or may be an AC voltage superimposed on the DC voltage. When a negative polarity DC voltage is applied to the discharge electrode 4, the handwriting can be erased particularly well. When a negative polarity DC voltage is applied to the discharge electrode 4, an ionization / dissociation gas composed of an oxidizing gas and its secondary products are efficiently generated, and these gas compositions are contained in, for example, ink. It is considered effective for lowering the color developability of dyes (particularly, anthraquinone dyes and methine dyes, more particularly CI Acid Blue 80, CI Acid Green 25 and CI Basic Violet 7).

  The discharge electrode 4 and the counter electrode 52 are appropriately selected according to the shape and structure of the discharge electrode 4 and the counter electrode 52 from those described as the constituent materials of the electrodes 31 and 32 of the creeping discharge electrode in relation to the creeping discharge. Can be configured. The same applies to the electrodes shown in FIGS. 5 and 7 to 9 described later.

  Corona discharge is started by applying a voltage equal to or higher than a predetermined threshold voltage (discharge start voltage). In the present invention, the DC voltage applied to the discharge electrode is preferably −0.5 kV to −20.0 kV, particularly −0.5 kV to −10.0 kV, more preferably −0.1 kV, and the discharge electrode and writing. It is preferable that the distance from the used medium is 30 mm or less (including 0 mm when they are in contact). When these conditions are adopted, the handwriting can be erased more efficiently.

  The shape of the discharge electrode 4 is not particularly limited. For example, as the discharge electrode 4, in addition to a wire shape, a known shape such as a roll shape, a blade shape, a plate shape, a brush shape, a needle shape, and a bar shape can be used. In particular, when corona discharge is performed, by using a corona charger using a wire-like conductive material as a discharge electrode, erasure of handwriting can be achieved uniformly over a wide area.

  Although the written medium 1 is preferably in contact with the counter electrode 52, it is not necessarily in contact. When the written medium 1 is present in the discharge region (the region centered between the discharge electrode 4 and the counter electrode 52), the medium 1 may be kept stationary or relatively moved with respect to the discharge region. Often, either stationary or moving is selected according to the purpose. When the exposure to the oxidizing gas is performed while moving the written medium 1, the moving speed of the medium 1 is appropriately selected depending on the concentration of the oxidizing gas and the distance between the discharge electrode and the medium 1. When the distance is within the above-mentioned range, the moving speed of the medium 1 is preferably 2000 cm / min or less, more preferably 500 cm / min or less. When the medium 1 is moved at such a moving speed, the efficiency is further increased. The handwriting can be erased.

  As described for the creeping discharge, the written medium 1 may be exposed to the oxidizing gas in a closed system or in an open system, and either system is selected according to the purpose. be able to. Preferably, it is performed in a closed system. When performed in a closed system, the medium 1 can be placed in a place other than the discharge region (region centered between the discharge electrode 4 and the counter electrode 52).

  FIG. 5 is a schematic side view showing another embodiment of an apparatus for erasing handwriting from a written medium 1 by corona discharge. In FIG. 5, the same members or parts as those in the apparatus shown in FIG. In the example shown in FIG. 5, the written medium 1 is transported on a conductive plate 52 ′ serving as a placement unit using two rolls 54.

  FIG. 7 is a schematic side view showing another embodiment of an apparatus for erasing handwriting from a written medium 1 by corona discharge. In FIG. 7, the same members or portions as those in the apparatus shown in FIG. FIG. 7 shows an example of an apparatus provided with a roll-shaped discharge electrode 4. The roll-shaped discharge electrode 4 is in contact with the conductive endless belt 52, and is rotated along with the rotation of the conductive endless belt 52, and a voltage is applied simultaneously. Since the written medium 1 passes through the discharge region while being in contact with both the roll-shaped discharge electrode 4 and the conductive endless belt 52, the contact efficiency with the oxidizing gas is improved.

  FIG. 8 is a schematic side view showing another embodiment of an apparatus for erasing handwriting from a written medium 1 by corona discharge. In FIG. 8, the same members or parts as those in the apparatus shown in FIG. FIG. 8 shows an example in which a conductive drum 52 is used as a conveying means that is a placement unit.

  FIG. 9 is a schematic side view showing another embodiment of an apparatus for erasing handwriting from a written medium 1 by corona discharge. In FIG. 9, the same members or parts as those in the apparatus shown in FIG. FIG. 9 shows an example in which a roll-shaped discharge electrode 4 and a conductive drum 52 are used as a conveying means that is a placement unit.

  The apparatus described with reference to FIGS. 1 to 9 is an example of the handwriting erasing apparatus of the present invention, and the apparatus of the present invention may have a configuration other than the illustrated configuration. In either case, the handwriting written on the recording medium is erased by the oxidizing gas, so that the recording medium can be reused as a medium for writing again or the handwriting is erased. The recording medium can be stored or discarded. The degree of erasure of the handwriting can be evaluated by, for example, obtaining the color difference (ΔE) between the handwriting and the white paper using a color difference meter CR-241 manufactured by the former Minolta Co., Ltd., and the color difference is 7.0. Less than, preferably less than 6.0. If necessary, the handwriting erasing operation may be performed twice or more. That is, the handwriting erased once by the handwriting erasing device may be erased again by the handwriting erasing device so that the handwriting is further erased.

  In the erasing method and erasing apparatus of the present invention, a substrate having the writing surface forming layer is used as a recording medium, and a writing tool is a dye that is erased by an oxidizing gas, preferably an anthraquinone dye and a methine dye, More preferably, a writing instrument using an ink composition containing at least one dye selected from CI Acid Blue 80, CI Acid Green 25 and CI Basic Violet 7 as an ink, such as a core-type writing instrument and a gel ink ballpoint pen, is used. Therefore, the erasing apparatus of the present invention can be provided as a handwriting erasing system in combination with the specific recording medium and writing instrument. The specific recording medium and a writing instrument for writing on the recording medium can be provided as a dedicated product of the system.

(Preparation of writing instruments)
[Production of gel ink ballpoint pen]
Eight types of gel inks A to H having the compositions shown in Tables 1 and 2 were prepared using two types of dyes. Fill the polypropylene ink storage tube with a stainless ballpoint pen tip (ball material: ceramics, ball diameter: 0.8 mm) at one end with gel ink, fill with an ink backflow preventer (polybutene gelled), A refill was made. Next, after attaching a ballpoint pen refill to the main body and attaching a cap, air in the tube was removed by a centrifuge, and then a tail plug was attached to obtain a gel ink ballpoint pen.

[Fabrication of core writing instrument]
Ink I having the composition shown in Table 3 was prepared using CI Basic Violet 7 as a dye. This ink was filled into a core-type writing instrument (trade name Sakura Line Marker OA2) to obtain a core-type writing instrument having a wide nib (about 4 mm in width) and a narrow nib (about 1 mm in width).

In the compositions shown in Tables 1 to 3, the following were used as each component.
Water-soluble organic solvent 1: Propylene glycol Water-soluble organic solvent 2: Glycerin Water-soluble polymer: Xanthan gum (trade name “Kelzan” manufactured by Sanki Co., Ltd.)
Dye: Ink A to D Acid Blue 80
Ink E ~ H Acid Green 25
Preservative: Benzisothiazoline-3-one (trade name “Proxel XL-2”, manufactured by Arch Chemicals)
Anti-fungal agent: Trade name “Coatside H”, manufactured by Nippon Enviro Chemicals

  As for the viscosity of the ink composition, for inks B to D and F to H, an ELD type viscometer (manufactured by Tokimec Co., Ltd.) was used, and the condition was 3 ° (R14) cone rotation speed 0.5 rpm (20 ° C.) For inks A, E and I, the same viscometer was used and measured at a 1 ° 34 ′ (R24) cone and a rotation speed of 50 rpm (20 ° C.). The φ0.8 assembly writing property was evaluated by whether or not the ink exudes smoothly when writing on a recording medium using the assembled writing instrument. The line marker writing property was evaluated based on whether or not the ink oozed smoothly and had a sufficient density when writing on a recording medium.

(Preparation of recording medium)
As a writing surface forming layer, a layer having the composition shown in Table 2 was formed in an amount of 10 g / m ^{2 on} a high-quality paper having a basis weight of 64 g / m ² . The writing surface forming layer is prepared by preparing a coating solution in which the components shown in Table 2 are dissolved or dispersed in water at a ratio of 21% by mass, and applying this with an air knife coater. It was formed by drying using.

  In the composition shown in Table 2, PVA represents polyvinyl alcohol (trade name 117K, manufactured by Kuraray Co., Ltd.), and EVA represents ethylene vinyl acetate (trade name, Sumikaflex S-401HQ, manufactured by Sumitomo Chemical Co., Ltd.). The cationic polymer used in the recording medium 1 is polyacrylamide diallylamine hydrochloride co-product (trade name Sumirez Resin 1001 manufactured by Sumika Chemtex Co., Ltd.), and the cationic polymer used in the recording medium 2 is diallyldimethylammonium. It is an amine polymer (trade name PAS-H-5L manufactured by Nitto Boseki Co., Ltd.) having chloride as a repeating unit.

  The writing surfaces of the recording media 1 to 3 are written using the writing tools assembled by filling the gel inks A to H, respectively, and the written recording medium is exposed to an oxidizing gas to erase the handwriting. The erasability of each combination of writing instruments was evaluated. In addition, writing with a core-type writing instrument was carried out using a thick nib. Here, ozone was generated as an oxidizing gas by using a device for generating corona discharge as shown in FIG. Corona discharge was generated by applying a DC voltage of 5 kV to the discharge electrode to generate ozone. The written recording medium was exposed to ozone while being conveyed at a speed of 600 mm / min. The operation of exposing to ozone was carried out twice, and the erasability when exposed to the first time was evaluated as one erasure, and the erasability when exposed to the second time was evaluated as erasing twice. The evaluation results are shown in Table 3.

The erasability of handwriting was evaluated by determining the color difference (ΔE) between the handwriting and the paper using a color difference meter CR-241 manufactured by the former Minolta Co., Ltd. The smaller this difference is, the better the handwriting is erased. The color difference is expressed by the following formula. In the formula, L ^* represents a lightness index, and a ^* and b ^* represent a chromaticness index. Details are described in the instruction manual of the device (especially page 77).

  The handwriting written on recording media 1 and 2 in which the writing surface-forming layer contains a cationic polymer is clearly erased when exposed to ozone gas compared to PPC paper without the writing surface-forming layer. In the combination of ink and medium, ΔE was 7 or less. When ΔE is 7 or less, the blue or green of the handwriting disappears, but it is visually confirmed that the shape of the handwriting remains light yellow. The writing surface of the ink A to C, E to G and H written on the recording medium 2 containing a polymer containing a repeating unit having a quaternary ammonium salt is erased for the first time or the second time. In operation, ΔE was less than 6, and disappeared as well as the handwriting was hardly confirmed by visual observation.

  The erasability also changed depending on the viscosity of the ink. The higher the viscosity, the higher the first erasability and the better the erasability. Therefore, very good erasability was obtained in the combination of the recording medium 2 and the inks B, C, F and G. However, when the viscosity of the ink was too high, the writing property deteriorated, the handwriting itself was faded, and the color difference from the paper was reduced. Therefore, the erasability was not evaluated for inks D and H.

  When the first erasability is good (particularly when ΔE is less than 6), ΔE may be higher than ΔE in the first evaluation in the second evaluation. This is because the ink was erased very well when exposed to ozone the first time, and when exposed to ozone the second time it was not erased more than when the ink was exposed to ozone the first time. It is thought that this is because an error caused by the ink density or the like appears as it is.

  The handwriting erasing method and apparatus of the present invention erases handwriting written with a writing instrument on a recording medium (especially paper) and enables reuse of the recording medium. It is useful as a recycling system for use in government offices and schools.

It is a side view which shows typically an example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention. It is a side view which shows typically another example of the handwriting erasing apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Written recording medium 2 AC power supply 3 Creeping discharge electrode 31 Electrode 32 Electrode 33 Dielectric 34 Discharge area 4 Discharge electrode 41 Cover 42 Sealed container 5 Mounting part 51 2nd bias electrode (conductive endless belt)
52, 52 ′ placing portion 53 roll 54 roll 6 first bias electrode

Claims (14)

  A method for erasing handwriting written with a writing instrument on a surface of a recording medium having a base material and a layer containing an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the base material. A method of erasing the handwriting, comprising: generating an oxidizing gas; and exposing the handwriting to the oxidizing gas.   The method according to claim 1, wherein the cationic polymer is an amine-based polymer.   The method according to claim 1, wherein the amine-based polymer is a polymer including a repeating unit having a quaternary ammonium salt.   The method according to any one of claims 1 to 3, wherein the writing instrument is a writing instrument that uses, as an ink, an ink composition containing at least one dye selected from an anthraquinone dye and a methine dye as a pigment.   Generating an oxidizing gas is a voltage between a first electrode and a second electrode separated by a dielectric having a surface for creeping discharge in an atmosphere of a gas capable of generating an oxidizing gas by discharge. The method of any one of Claims 1-4 including generating a creeping discharge from the said surface for said creeping discharge by applying.   The generation of an oxidizing gas is performed by applying a negative voltage to the second electrode with respect to the grounded first electrode in an atmosphere of a gas that can generate an oxidizing gas by discharge. 5. The method according to any one of claims 1 to 4, comprising performing a corona discharge. An apparatus for erasing handwriting written with a writing instrument on the surface of a recording medium having a base material and a layer containing an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the base material. And
(A) an oxidizing gas generating means, and (b) a placing portion on which the written recording medium is placed, and the oxidizing gas generating means and the placing portion are such that the written recording medium is exposed to the oxidizing gas. Handwriting eraser arranged so that. The oxidizing gas generating means is
Having a first electrode, a second electrode, and a dielectric separating these electrodes;
The dielectric has a surface that generates creeping discharge by applying a voltage between these electrodes.
The handwriting erasing apparatus according to claim 7, which is creeping discharge generating means. The oxidizing gas generating means is
Having a first electrode and a second electrode;
Corona discharge is generated by applying a negative voltage to the second electrode with respect to the grounded first electrode.
The handwriting erasing apparatus according to claim 7, which is a corona discharge generating means. The handwriting erasing device according to any one of claims 7 to 9,
A base material, a recording medium having a layer containing an inorganic pigment, a binder, and a cationic polymer formed on at least one surface of the base material, and an ink composition that can be erased by an oxidizing gas, as the ink, A handwriting erasing system including a writing instrument used for writing on a recording medium.   A recording medium in which a handwriting written by a writing instrument is erasable, and has a layer containing an inorganic pigment, a binder, and a cationic polymer on at least one surface.   The recording medium according to claim 11, wherein the cationic polymer is an amine polymer.   The recording medium according to claim 11, wherein the cationic polymer is a polymer including a repeating unit having a quaternary ammonium salt.   A writing instrument, which is used for writing on a recording medium according to any one of claims 11 to 13 and uses, as an ink, an ink composition containing at least one dye selected from an anthraquinone dye and a methine dye as a pigment. .

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