JP2006137905A - Method for reusing recording medium and reusable recording medium therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for reusing limited resources for recording medium and provide reusable recording medium that can be used repeatedly for this purpose. <P>SOLUTION: A thermally vanishable ink composition comprising a combination of a thermally decomposable color developer at 100°C to 180°C and a colorless leuco dye is applied on the surface of the recording medium to record an image. Then, the recording medium is heated at 100°C to 180°C to erase the image and the surface of the recording medium is made reusable. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of reusing a recording medium for erasing a recorded image by heating and returning it to a rerecordable state, and a reusable recording medium used therefor.

Recently, with the widespread use of office automation equipment including personal computers and printers, the opportunity to print information created on personal computers on paper has increased greatly. After checking the printed content, the paper that is no longer needed is used as underlaying paper or a memo, but it is usually discarded after that. A business that collects and recycles paper discarded in large quantities in offices and the like has already been operated from the viewpoint of effective use. However, for example, a small number of papers discarded at home are generally disposed of as combustible waste.
In this regard, for example, a method has been proposed in which an information image printed by a printer is erased by heat treatment to return the paper to a reusable state (see Patent Documents 1 and 2). These utilize the thermal characteristics of the thermally erasable ink composition, but a special printer is required because the image printing temperature and the thermal erasing temperature are different from each other.

  As another method, a marker pen using a heat-erasable ink composition is also known (see Patent Documents 3 and 4). This marker pen is intended for handwriting an image on a reversible thermosensitive recording material including thermal paper. In other words, the thermal recording image formed on the thermal paper by the thermal printer and the handwritten image added with the marker pen on the thermal recording image are simultaneously erased by one heat treatment.

Japanese Patent No. 3286214 JP-A-7-81236 JP-A-9-165537 Japanese Patent Application Laid-Open No. 10-77437

  However, recently, with the spread of bubble jet printers and laser printers, plain paper is often used rather than thermal paper. Usually, the ink composition from the marker pen soaks into plain paper, so that erasure by heat treatment may be incomplete.

  Accordingly, the object of the present invention is to prevent the penetration of a thermally erasable ink composition into these materials without hindering printing by a general-purpose printer other than a thermal transfer printer on paper, sheets or films including plain paper. In addition, it is easy to thermally erase an image printed or handwritten with the ink composition.

  It has been found that the above object can be achieved by providing a special ink receiving layer on the surface of the recording medium and using the thermally erasable drawing material described in Japanese Patent No. 1445357 as a thermally erasable ink composition. Here, the patent is a prior application of the present applicant. The ink composition described in this publication is already in a colored state at the time of use, and an image is recorded by simply applying it to a recording medium. The recorded image does not change almost permanently at room temperature, but can be easily erased by heating the recording medium to a specific temperature. As a result, the surface of the recording medium returns to the state before image recording and can be reused for image recording.

  Therefore, the present invention records an image on the surface of a recording medium by applying a heat erasable ink composition containing a combination of a heat decomposable developer having a decomposition temperature of 100 ° C. to 180 ° C. and a colorless leuco dye. Then, the recording medium is reused by heating the recording medium to 100 ° C. to 180 ° C. to erase the image and returning the surface of the recording medium to a rerecordable state.

  The present invention further provides a reusable recording medium having heat resistance and dimensional stability used in the method of the present invention.

According to the present invention, a recording medium having a special ink receiving layer on the surface and a heat erasable ink composition containing a combination of a heat decomposable developer and a colorless leuco dye as a coloring component are used in combination. Thus, it is possible to repeatedly perform image recording on the recording medium and thermal erasure of the image, and as a result, resource saving of the recording medium can be easily achieved.
In the present invention, a special ink-receiving layer is provided not only on paper but also on a film or sheet, and by applying the heat-erasable ink composition thereto, a wide variety of recording media can be reused.

BEST MODE FOR CARRYING OUT THE INVENTION

  In the method of reusing a recording medium of the present invention, an image is recorded by applying a heat erasable ink composition on the surface of the recording medium, and then the recording medium is heated to 100 ° C. to 180 ° C. to erase the image. , Returning the surface of the recording medium to a re-recordable state.

Recording medium and rewritable medium The recording medium used in the method of the present invention may be any medium as long as it is resistant to the heating temperature applied when erasing the recorded image and has good dimensional stability. For example, it may be in the form of a paper, a film, a sheet or the like usually used for printing by a printer.

  As shown in FIG. 1, an ink receiving layer is provided on the surface of the recording medium. The ink receiving layer clearly expresses a desired image when the heat erasable ink composition having the above composition is applied, and prevents the ink composition from penetrating into the recording medium, thereby erasing the image with heat. The purpose is to make it easier. Due to the presence of this ink receiving layer, after an image is recorded by applying a heat erasable ink composition, which will be described later, when the recording medium is heated to 100 ° C. to 180 ° C., the recorded image is erased and the image can be recorded again Return to.

  The ink receiving layer may contain at least one selected from the group consisting of polyester resins, polyamide resins, cellulose resins, calcium carbonate, magnesium carbonate, and titanium dioxide. Any method known in this field can be used to form the ink receiving layer on the recording medium. Examples thereof include flexo coating, gravure coating, meaver coating, reverse coating, and air knife coating. The thickness of the ink receiving layer thus formed may be, for example, in the range of 3 μm to 10 μm.

Heat erasable ink composition In the method of the present invention, the heat erasable ink composition applied to the ink receiving layer on the surface of the recording medium is colored when applied to the ink receiving layer of the recording medium, and then subjected to heat treatment. It is characterized by erasing the color. Such a heat-erasable ink composition contains a combination of a heat-decomposable developer having a decomposition temperature of 100 ° C. to 180 ° C. and a colorless leuco dye as a coloring component. Here, the combination of the thermally decomposable developer and the colorless leuco dye may most preferably be that described in the specification of the above-mentioned Patent No. 1445357. Hereinafter, the heat erasable ink composition will be described in more detail.

(1) Thermally decomposable developer The thermally decomposable developer suitably used in the present invention is substantially decomposable at room temperature and decomposes by heat to become sublimable, particularly 100 ° C to 180 ° C. When it is heated, it decomposes and sublimates. Such a thermally decomposable developer is at least one selected from the group consisting of zinc salts, tin salts, zirconium salts and aluminum salts of aromatic carboxylic acids including salicylic acid, benzoic acid and substituted benzoic acid, Good. Specific examples include zinc salicylate and substituted derivatives thereof, benzoic acid and substituted benzoic acid; Metal salts of salicylic acid derivatives [eg, zinc salt of 5-phenylsalicylic acid, zinc salt of 5-t-amylsalicylic acid, zinc salt of 5- (4-hydroxyphenyl) -salicylic acid, 3,5-di (α-methylbenzyl ) -Zinc salt of salicylic acid, zinc salt of 3-methyl-5-phenyl-salicylic acid, etc.]; or zinc salt of condensate of salicylic acid and formaldehyde.

  From the viewpoints of thermal decomposition temperature, color developability and sublimability, zinc salicylate is used alone as the most preferable thermal decomposable developer. Furthermore, the sublimation temperature can be adjusted by using zinc salicylate together with an appropriate compound such as zinc benzoate according to the application.

(2) Colorless leuco dye Examples of the incompetent leuco dye that develops color by the action of the thermally decomposable developer, particularly zinc salicylate, include compounds having a lactone ring:

And a compound having a lactam ring:

等が使用されてよい。あるいは、上記以外に、無色のスピロピラン系、フルオラン系、フェノチアジン系化合物を補色程度の量で用いてもよい。 Or leucooramine compounds:

Etc. may be used. Alternatively, in addition to the above, a colorless spiropyran-based, fluoran-based, or phenothiazine-based compound may be used in a complementary color amount.

  In the heat-erasable ink composition, the mixing ratio of the heat-decomposable developer and the colorless leuco dye is usually 30: 1 to 30:90, preferably about 10: 1 to 10:20. .

  The heat-erasable ink composition may further contain waxes for the purpose of improving the depictability of the recorded image, if necessary. As the waxes, among those usually used for the production of carbon paper, those close to colorless are preferable, for example, carnauba wax, bleached montan wax, auricule wax, candelilla wax, oxidized microwax, sasol wax, It may be Hoechst wax, paraffin wax, stearic acid, palmitic acid or the like. When using a combination of a thermally decomposable developer and a colorless leuco dye, the waxes act as a solvent for the leuco dye, and further, coloring components, that is, a thermally decomposable developer and a colorless leuco dye, Or the color development and decoloring properties of the low-temperature sublimable dye.

  The heat-erasable ink composition may contain petroleum oil, alkylnaphthalene, triallylmethane, or the like as the plasticizer for the wax.

  The heat erasable ink composition comprises the above-mentioned composition and, if necessary, various additives usually used in the field (external pigments, resins such as calcium carbonate and magnesium carbonate, which do not adversely affect the decoloring properties of coloring components) And waxes and dispersants).

  In the method of the present invention, the heat erasable ink composition having the above composition is in the form of a writing instrument (for example, a ballpoint pen, a sign pen or a marker pen) filled with the ink composition in a container, or a printer ink for an ink jet printer. Can be used as

  FIG. 1 shows a schematic process diagram in which an image 31 is recorded on the ink receiving layer 2 of the recording medium 1 using the writing tool 3 and erased by heat treatment. The heat-erasable ink composition used for such a writing instrument is preferably a combination of a heat-decomposable developer and a colorless leuco dye, or 30 to 60 parts by weight of a low-temperature sublimable dye, if necessary. 10 to 20 parts by weight, 5 to 10 parts by weight of a plasticizer for wax and 20 to 40 parts by weight of an additive containing extender pigments are mixed with each other, and the resulting mixture is mixed with a suitable solvent (toluene, methyl ethyl ketone, ethyl acetate, bromopropane). It is prepared by dissolving or dispersing in (1).

  Alternatively, when the heat erasable ink composition is provided as a printer ink, the combination of the heat decomposable color developing property and the colorless leuco dye or the low temperature sublimable dye 30 to the total weight of the heat erasable ink composition. If necessary, 60 to 20 parts by weight of waxes, 10 to 20 parts by weight of wax, 5 to 10 parts by weight of plasticizer for wax and a total of 20 to 40 parts by weight of additives including extender pigments are mixed with each other, and the resulting mixture is appropriately mixed. It is prepared by dissolving or dispersing in a solvent (toluene, xylene, methyl ethyl ketone, bromopropane).

  According to the present invention, an image is recorded on the ink receiving layer on the surface of the recording medium using a heat-erasable ink composition of a suitable form, and then the recording medium is subjected to a specific temperature, preferably 100 ° C to 180 ° C. Most preferably, the recorded image is erased by heating to 130 to 150 ° C. After thermal erasing of the image, the recording medium itself including the ink receiving layer maintains its excellent heat resistance and dimensional stability, and the ink receiving layer returns to a recordable state.

Example 1 (Reusable image forming paper)
As the recording medium, a western paper (white paper) having an ink receiving layer (thickness: 5 μm) formed in advance by applying a polyester resin and calcium carbonate to the surface with a gravure coater was used. On this ink receiving layer, an image was recorded by hand using a marker pen filled with an ink composition having the following composition.

  Next, when the paper was applied to a heat roll apparatus heated to 100 ° C. to 180 ° C., the entered image was erased and the paper was returned to a blank paper state.

  The above procedure (recording an image with a marker pen on western paper and subsequent thermal decoloring) was repeated 50 times. This confirmed that the paper could withstand repeated reuse.

Example 2 (Reusable, imaging film)
The reusable recording medium of the present invention was prepared by applying an ink receiving layer comprising a polyester resin and calcium carbonate on the surface of the rewritable thermal film at a dry film thickness of 3 μm and drying.

  An image was recorded on the ink receiving layer of this recording medium with the marker pen used in Example 1. When the film was applied to a heat roll apparatus heated to 100 ° C. to 180 ° C. after image recording, the entered image was erased and the film returned to the state before recording.

  The above procedure (recording an image on the film with a marker pen and subsequent thermal decoloring) was repeated 50 times. This confirmed that the film could sufficiently withstand repeated reuse.

It is a typical process figure showing one mode of the method of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording medium, 2 ... Ink receiving layer, 3 ... Writing instrument which filled the heat erasable ink composition in the container, 31 ... Image

Claims (7)

An image is recorded on the surface of the recording medium by applying a heat-erasable ink composition containing a combination of a heat-decomposable developer having a decomposition temperature of 100 ° C. to 180 ° C. and a colorless leuco dye, and then the recording medium is made 100 A method for reusing a recording medium, comprising: erasing the image by heating to from about 180 ° C. to about 180 ° C., and returning the surface of the recording medium to a rerecordable state. The reusable recording medium according to claim 1, wherein the thermally decomposable developer is at least one selected from the group consisting of zinc salt, tin salt, zirconium salt and aluminum salt of salicylic acid, benzoic acid and substituted benzoic acid. Method. The method for reusing a recording medium according to claim 2, wherein the thermally decomposable developer is a mixture of a phenol derivative and a zinc salt of a salicylic acid derivative. The method for reusing a recording medium according to claim 1, wherein the heat erasable ink composition is applied through a writing instrument comprising a container filled with the ink composition. The method for reusing a recording medium according to claim 1, wherein the heat erasable ink composition is applied as a ballpoint pen, a marker, or an ink jet printer ink. A reusable recording medium having heat resistance and dimensional stability, having an ink receiving layer on the surface thereof, and a thermally decomposable developer having a decomposition temperature of 100 ° C. to 180 ° C. An image is recorded by applying a heat erasable ink composition containing a combination of a leuco dye and a colorless leuco dye, and when the image is recorded and heated to 100 ° C. to 180 ° C., the image is erased and can be recorded again A reusable recording medium characterized by returning to a new state. The reusable recording medium according to claim 6, wherein the ink receiving layer contains at least one selected from the group consisting of a polyester resin, a polyamide resin, a cellulose resin, calcium carbonate, magnesium carbonate, and titanium oxide.

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