JP2011079236A - Noncontact type record rewriting medium and method for rewriting the record rewriting medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a noncontact type record rewriting medium in which visible information can be recorded and erased by laser beams in a noncontact state and which has excellent light resistance, can suppress deterioration of erasability of recorded information due to lapse of time and further is excellent in visibility of the recorded information. <P>SOLUTION: The noncontact type record rewriting medium is constituted by providing a reversible thermosensitive color developing layer on one surface of a support and visible information can be rewritten by laser beams in the noncontact state and a resin layer having at least one nontransmittance peak in a visible light region of 500 to 700 nm is laminated on the reversible thermosensitive color developing layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a non-contact type recording / rewriting medium and a method for rewriting the recording / rewriting medium. More specifically, the present invention relates to a non-contact type recording / rewriting medium capable of recording / erasing visible information in a non-contact manner with a laser beam, having excellent light resistance, and capable of suppressing deterioration in erasability of recorded information over time. And a method for rewriting the recording / rewriting medium.

Conventionally, labels used for the management of goods, such as labels attached to plastic containers for transporting food, labels used for management of electronic components, logistics management labels attached to cardboard, etc., thermal recording materials (direct thermal paper, etc.) The thing which used this for the surface base material has become mainstream.
This heat-sensitive recording material is provided with a heat-sensitive recording layer mainly comprising an electron-donating usually colorless or light-colored dye precursor and an electron-accepting developer on a support. By heating with, for example, the dye precursor and the developer react instantaneously to obtain a recorded image. In general, once such an image is formed, such a heat-sensitive recording material cannot be erased and returned to the state before image formation again.

  Until now, in the label used for the above-mentioned article management, such a heat-sensitive recording material has been mainly used as a surface base material, and using a contact-type thermal printer or the like, the destination, sender, article name, quantity, weight In addition, information such as date of manufacture, expiration date, unique identification number, lot number, etc., and bar codes of these were printed and affixed to the adherend. When the role as a label is completed, it takes a lot of time and labor to manually peel off the label in order to reuse the container and cardboard as the adherend. In addition, the adherend from which the label has been peeled is affixed again with another label and used repeatedly.

  As described above, every time the adherend is repeatedly used, the label is peeled off and pasted. For this reason, in recent years, rewritable thermal labels that can repeatedly record and erase information while being attached to the adherend without peeling the label from the adherend each time have attracted attention. A non-contact type reversible thermosensitive recording material having a visible information recording / erasing means provided with a thermosensitive coloring layer containing a photosensitive developer has been developed (see, for example, Patent Documents 1 to 3).

However, in such non-contact reversible thermosensitive recording materials, exposure to visible and ultraviolet light, including sunlight, causes decomposition of dyes that are dye precursors and light-absorbing heat conversion agents, resulting in recording information. There is a problem that the erasability of the recording medium deteriorates, and this causes a problem that the repetitive recording ability deteriorates, and a color change of recorded characters and recording materials occurs, resulting in a problem that visibility decreases.
Therefore, a non-contact type recording / rewriting medium having excellent light resistance has been desired.

JP 2003-118238 A JP 2006-231647 A Japanese Patent No. 2741435

  Under such circumstances, the present invention is capable of recording and erasing visible information in a non-contact manner with laser light, has excellent light resistance, and can suppress deterioration in erasability of recorded information over time. An object of the present invention is to provide a non-contact type recording / rewriting medium excellent in the visibility of recorded information and a method for rewriting the recording / rewriting medium.

As a result of intensive studies to achieve the above object, the present inventors have found that at least one visible light region of 500 to 700 nm is formed on the reversible thermosensitive coloring layer provided on one surface of the support. By laminating a resin layer having a non-transmittance peak and preferably having a transmittance of 80% or more of laser light (wavelength 800 to 1400 nm) used for recording and erasing information, it can meet the purpose. It has been found that a non-contact type recording / rewriting medium can be obtained.
Further, the present inventors have found that recording information can be efficiently rewritten by performing recording on this non-contact type recording / rewriting medium by irradiation with laser light and erasing the recording by irradiation with laser light or heat treatment.
The present invention has been completed based on such findings.

That is, the present invention
(1) A non-contact type recording / rewriting medium in which a reversible thermosensitive coloring layer is provided on one surface of a support, and rewrites visible information by laser light in a non-contact manner, on the reversible thermosensitive coloring layer. A non-contact type recording / rewriting medium, wherein a resin layer having at least one non-transmittance peak is laminated in a visible light region of 500 to 700 nm,
(2) The non-contact type recording / rewriting medium described in the above item (1), wherein the peak value of the maximum non-transmittance in the visible light region of 500 to 700 nm is in the range of 40 to 98%,
(3) The non-contact recording / rewriting medium according to (1) or (2), wherein the total light transmittance in a visible light region of 400 to 800 nm is 70% or more,
(4) Any of the above items (1) to (3), wherein the wavelength of the laser beam to be used is in the range of 800 to 1400 nm, and the transmittance of the laser beam at the wavelength of the laser beam of the resin layer is 80% or more. A non-contact type recording / rewriting medium according to claim 1,
(5) The non-contact recording / rewriting medium according to any one of (1) to (4), wherein the resin layer comprises a laminate film and an adhesive layer;
(6) The non-contact recording / rewriting medium described in (5) above, wherein the laminate film is a polyethylene terephthalate multilayer laminated film, and (7) the non-contact described in any one of (1) to (6) above. A recording / rewriting method for a non-contact type recording / rewriting medium, characterized in that recording is performed by irradiating a laser beam on a mold recording / rewriting medium, and the recording is erased by irradiation with a laser beam or heat treatment,
Is to provide.

According to the present invention, a reversible thermosensitive coloring layer is provided on one side of the support, and has at least one non-transmittance peak in the visible light region of 500 to 700 nm, and is preferably used. By laminating a resin layer having a laser beam (wavelength 800 to 1400 nm) transmittance of 80% or more, visible information can be recorded / erased in a non-contact manner with a laser beam, and the light resistance is excellent. It is possible to provide a non-contact type recording rewritable medium that can suppress deterioration in erasability of recorded information and is excellent in the visibility of recorded information.
The non-contact type recording / rewriting medium of the present invention can suppress a decrease in erasability even when it is recorded and affixed to an adherend and left outdoors or indoors. Further, even if the resin layer is laminated, the visibility of the recording and erasure by laser light and the thermal color development recording by visual observation is not deteriorated.

It is an image figure of an example of the non-contact-type recording / rewriting medium of this invention. 4 is a graph showing the relationship between wavelength and non-transmittance in the resin layer used in Example 1. It is a graph which shows the relationship between the wavelength and the non-transmittance in the resin layer used in Example 2. It is a graph which shows the relationship between the wavelength and the non-transmittance in the resin layer used in Example 3. It is a graph which shows the relationship between the wavelength and the non-transmittance in the resin layer used in Example 4. It is a graph which shows the relationship between the wavelength and the non-transmittance in the resin layer used in Example 5. It is a graph which shows the relationship between the wavelength and the non-transmittance in the resin layer used in Example 6. It is a graph which shows the relationship between the wavelength and the non-transmittance in the resin layer used in Example 7. 5 is a graph showing the relationship between wavelength and non-transmittance in the resin layer used in Comparative Example 1. It is a graph which shows the relationship between the wavelength and the non-transmittance in the resin layer used in Comparative Example 2. 10 is a graph showing the relationship between wavelength and non-transmittance in the resin layer used in Comparative Example 3.

  The non-contact type recording / rewriting medium of the present invention is a non-contact type recording / rewriting medium in which a reversible thermosensitive coloring layer is provided on one surface of a support and the visible information is rewritten in a non-contact manner with a laser beam. The resin layer having at least one non-transmittance peak in the visible light region of 500 to 700 nm is laminated on the reversible thermosensitive coloring layer.

[Support]
In the non-contact type recording / rewriting medium of the present invention (hereinafter sometimes simply referred to as “recording medium”), the support is not particularly limited. For example, polystyrene, acrylonitrile-butadiene-styrene resin, polycarbonate, polypropylene, polyethylene , Polyethylene terephthalate (PET), foamed PET, polyethylene naphthalate and other plastic films, synthetic paper, nonwoven fabric, paper and the like. Although there is no restriction | limiting in particular as thickness of a support body, Usually, 10-500 micrometers, Preferably it is the range of 20-200 micrometers. Moreover, when using a plastic film as a support body, surface treatment can be performed by an oxidation method, an uneven | corrugated method, etc. as needed for the purpose of improving the adhesiveness with the layer provided in the surface. Examples of the oxidation method include corona discharge treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment and the like, and examples of the unevenness method include sand blast method and solvent treatment method. Is mentioned. These surface treatment methods are appropriately selected depending on the type of the support, but in general, the corona discharge treatment method is preferably used from the viewpoints of effects and operability.
It is also effective to use a foam film having a high heat insulating effect as a support in order to effectively use the heat at the time of recording information by laser light. Further, as the support, a plastic film excellent in repeated use suitability is preferable.

(Anchor coat layer)
In the recording medium of the present invention, an anchor coat layer can be provided on one surface of the support. This anchor coat layer protects the support from the solvent in the coating solution used to improve the adhesion between the reversible thermosensitive coloring layer and the support and when the reversible thermosensitive coloring layer is provided in the next step. By providing this anchor coat layer, a support having poor solvent resistance can be used.
There is no restriction | limiting in particular as resin which comprises this anchor coat layer, Although various things can be used, Crosslinked resin excellent in solvent resistance is used suitably. Examples of the crosslinked resin include an acrylic resin, a polyester resin, a polyurethane resin, and an ethylene-vinyl acetate copolymer that can be crosslinked. When a support having poor solvent resistance is used, it is preferable to use a coating solution that is not an organic solvent type, such as an aqueous solution type or a water dispersion type coating solution, for forming the anchor coat layer. Moreover, there is no restriction | limiting in particular as a crosslinking method, According to the kind of resin to be used, it can select suitably from conventionally well-known various methods.
Furthermore, it is also effective to use a resin that crosslinks and cures with ionizing radiation such as ultraviolet rays and electron beams as a solventless type. This ionizing radiation curable resin can easily adjust the crosslinking density by changing the irradiation dose, and can form a crosslinked resin having a high crosslinking density.

[Reversible thermosensitive coloring layer]
In the recording medium of the present invention, the reversible thermosensitive coloring layer (hereinafter sometimes simply referred to as “thermal coloring layer”) provided on the surface of the support is generally a colorless or light dye precursor, reversible color development. It is comprised from the agent and the light absorption heat conversion agent used as needed, a binder, a decoloring accelerator, an inorganic pigment, various additives, etc.
(Dye precursor)
There is no restriction | limiting in particular as a colorless or light-colored dye precursor, Arbitrary things can be suitably selected and used from the well-known compounds used as a dye precursor in the conventional heat-sensitive recording material. For example, 3,3-bis (4-dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-dimethylaminophenyl) -3- (1,2-dimethylindol-3-yl) phthalide, 3- ( Triarylmethane compounds such as 4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide, rhodamine B anilinolactam, 3- (N-ethyl) Xanthene compounds such as -N-tolyl) amino-6-methyl-7-anilinofluorane, diphenylmethane compounds such as 4,4'-bis (dimethylaminophenyl) benzhydrylbenzyl ether, N-chlorophenylleucooramine Compounds, spiro compounds such as 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, benzoylleucomet Nburu, p- nitrobenzoyl leuco methylene blue, etc. may be used to select one from among such thiazine-based compounds may be used in combination to select two or more.

(Reversible developer)
In the recording medium of the present invention, the reversible developer that can be used in the reversible thermosensitive coloring layer is one that causes a reversible color change in the dye precursor due to a difference in cooling rate after heating. Although there is no particular limitation, an electron-accepting compound composed of a phenol derivative having a long-chain alkyl group is preferable from the viewpoints of color density, decoloring property, and repeated durability.
The phenol derivative may have an atom such as oxygen or sulfur or an amide bond in the molecule. The length and number of alkyl groups are selected in consideration of the balance between decoloring properties and color developability, but the alkyl groups are preferably those having 8 or more carbon atoms, particularly those having about 8 to 24 carbon atoms. In addition, hydrazine compounds, anilide compounds, urea compounds having a long-chain alkyl group in the side chain can also be used.
Examples of the phenol derivative having such a long-chain alkyl group include 4- (N-methyl-N-octadecylsulfonylamino) phenol, N- (4-hydroxyphenyl) -N′-n-octadecylthiourea, N- (4-hydroxyphenyl) -N′-n-octadecylurea, N- (4-hydroxyphenyl) -N′-n-octadecylthioamide, N- [3- (4-hydroxyphenyl) propiono] -N′-octa Examples include decanohydrazide, 4′-hydroxy-4-octadecylbenzanilide.
Utilizing the crystallinity of such a reversible developer, when recording information, it is rapidly cooled after heating. Recording and erasing are possible.

(Light absorption heat conversion agent)
The light absorption heat conversion agent used as necessary for the reversible thermosensitive coloring layer has a function of absorbing the laser light to be irradiated and converting it into heat, and is appropriately selected depending on the laser light to be used. As the laser beam, it is preferable to select a laser beam having an oscillation wavelength in the range of 800 to 1400 nm from the viewpoint of the simplicity of the apparatus and the scanning property. For example, a semiconductor laser beam and a YAG laser beam are preferable.
The light absorbing heat converting agent preferably absorbs near-infrared laser light and generates heat, and does not absorb much light in the visible light region. When the light-absorbing heat converting agent absorbs visible light, the visibility and barcode readability of the rewritable recording medium of the present invention are lowered. Examples of the light absorption heat conversion agent satisfying such required performance include organic dyes and / or organometallic dyes. Specifically, at least one selected from cyanine dyes, phthalocyanine dyes, anthraquinone dyes, azulene dyes, squarylium dyes, metal complex dyes, triphenylmethane dyes, indolenine dyes, and the like. Can be mentioned.
When the light-absorbing heat converting agent is contained in the thermosensitive coloring layer, the content thereof is not particularly limited, but is usually 0.1 to 30% by mass, preferably 0.2, based on the total mass of the thermosensitive coloring layer. -10% by mass, more preferably 0.5-5% by mass.
In addition, a light absorption heat conversion layer can be provided on a heat sensitive color development layer as mentioned later, without adding the said light absorption heat conversion agent to a heat sensitive color development layer.

(Other ingredients)
Examples of the binder used as necessary for the purpose of maintaining each component constituting the thermosensitive coloring layer and maintaining uniform dispersibility include, for example, polyacrylic acid, polyacrylic acid ester, polyacrylamide, polyvinyl acetate, and polyurethane. , Polymers such as polyester, polyvinyl chloride, polyethylene, polyvinyl acetal, polyvinyl alcohol, and copolymers of monomers constituting them.
Further, as a decoloring accelerator used as necessary, for example, ammonium salts and the like, as inorganic pigments, for example, talc, kaolin, silica, titanium oxide, zinc oxide, magnesium carbonate, aluminum hydroxide, and the like are added. Examples of the agent include known leveling agents and dispersants.

(Formation of thermosensitive coloring layer)
In order to form a thermosensitive coloring layer, first, a coating liquid is prepared by dissolving or dispersing the dye precursor, the reversible developer, and various additive components used as necessary in an appropriate organic solvent. . In this case, as the organic solvent, for example, alcohol, ether, ester, aliphatic hydrocarbon, aromatic hydrocarbon and the like can be used, and tetrahydrofuran is particularly preferable because of its excellent dispersibility. Although there is no restriction | limiting in particular about the ratio of a dye precursor and a reversible developer, A reversible developer is 50-700 mass parts normally with respect to 100 mass parts of dye precursors, Preferably it is 100-500 mass parts. Used in a range.
Next, the thus-prepared coating solution is applied by a conventionally known means and dried to form a thermosensitive coloring layer. Although there is no restriction | limiting in particular about drying process temperature, It is desirable to dry at low temperature so that a dye precursor may not color. The thickness of the thermosensitive coloring layer thus formed is usually in the range of 1 to 10 μm, preferably 2 to 7 μm.

[Light absorption heat conversion layer]
In the recording medium of the present invention, a light-absorbing heat conversion layer can be provided on the heat-sensitive coloring layer as required without containing the above-mentioned light-absorbing heat conversion agent in the heat-sensitive coloring layer.
When a light-absorbing heat conversion layer is provided on the heat-sensitive color developing layer, the light-absorbing heat conversion layer is generally added to the light-absorbing heat conversion agent, a binder, and an inorganic pigment, an antistatic agent, or the like used as necessary. It is composed of agents.
As the binder, the same materials as those exemplified as the binder in the heat-sensitive coloring layer can be used, but the light-absorbing heat conversion layer is required to have transparency for visualizing the coloring of the lower layer. . Further, as the binder, a cross-linked resin is preferable, and an ionizing radiation curable resin such as an ultraviolet ray or an electron beam is particularly preferable.

(Formation of light absorption heat conversion layer)
In order to form the light absorption heat conversion layer, first, a coating liquid containing the light absorption heat conversion agent, a binder, and various additives used as necessary is prepared. At this time, depending on the type of the binder, an appropriate organic solvent may be used as necessary. Although there is no restriction | limiting in particular about the ratio of a binder and a light absorption heat conversion agent, A light absorption heat conversion agent is 0.01-50 mass parts normally with respect to 100 mass parts of binders, Preferably it is 0.03-10 mass parts. Used in a range. However, since the light absorption heat conversion agent may also absorb light in the visible light range, if the amount of the light absorption heat conversion agent is large, the light absorption heat conversion layer is in a normal state where no laser light is irradiated. There is a risk of coloring. When the light-absorbing heat conversion layer is colored, the light-absorbing heat-converting agent is taken into consideration not only the appearance of the recording medium but also the information visibility and barcode readability in consideration of the balance with the color development sensitivity due to heat generation. It is preferable to keep the blending amount of the above small.
Next, the coating solution thus prepared is coated on the thermosensitive coloring layer by a conventionally known means, and after drying treatment, it is crosslinked by heating, irradiation with ionizing radiation, etc., thereby absorbing light. A heat conversion layer is formed. The thickness of the light absorption heat conversion layer thus formed is usually 0.05 to 10 μm, preferably 0.1 to 3 μm.

[Resin layer]
In the non-contact type recording / rewriting medium of the present invention, a resin layer having at least one non-transmittance peak in the visible light region of 500 to 700 nm is laminated on the reversible thermosensitive coloring layer. In the present invention, the non-transmissivity is defined as the ratio of not transmitting light at each wavelength. Specifically, the transmittance at each wavelength was measured, and the transmittance value was subtracted from 100% to obtain non-transmittance. (Non-transmittance (%) = 100% -Transmittance (%))
The resin layer only needs to have at least one non-transmittance peak in the visible light region of 500 to 700 nm, and may have a plurality of non-transmittance peaks in the visible light region. You may have one or more non-transmittance peaks in the wavelength range below.
The resin layer preferably has a maximum non-transmittance peak value in the visible light region of 500 to 700 nm in the range of 40 to 98%, and more preferably in the range of 50 to 90%. Further, the resin layer naturally needs to be transparent so that information provided on the lower thermosensitive coloring layer can be visually recognized, and the total light transmittance in the visible light region of 400 to 800 nm is 70% or more, more preferably 80% or more. It is. In addition, with the total light transmittance said by this invention, each light transmittance in each wavelength is measured in the wavelength range of 400 nm-1400 nm using a spectrophotometer. Of these, the average light transmittance in the visible light portion (400 to 800 nm) is defined as the total light transmittance. Moreover, what has the transmittance | permeability of a laser beam with a wavelength of 800-1400 nm is 80% or more.

In conventional non-contact type recording / rewriting media, exposure to visible and ultraviolet light such as sunlight causes decomposition of dye precursors such as pigments and light-absorbing heat conversion agents, resulting in reduced erasability of recorded information. As a result, the repetitive recording performance is deteriorated, or the recorded characters and the recording material are discolored, resulting in a decrease in visibility.
In the non-contact type recording rewritable medium of the present invention, by laminating the resin layer having the optical characteristics described above on the thermosensitive coloring layer, it is possible to record / erase visible information in a non-contact manner with a laser beam, The light resistance is improved, the deterioration of the erasability of the recorded information with time can be suppressed, and the visibility of the recorded information is improved.
In addition, the recording medium of the present invention can suppress a decrease in erasability even when it is left outdoors or indoors with visible information recorded and attached to an adherend or the like. Further, even if the resin layer is laminated, the visibility of the recording and erasure by laser light and the thermal color development recording by visual observation is not deteriorated.

In the recording medium of the present invention, the resin layer having the above-described optical properties provided on the heat-sensitive color-developing layer is usually composed of a laminate film and an adhesive layer, and the laminate film includes the resin layer described above. From the viewpoint of optical properties, a polyethylene terephthalate multilayer laminated film can be preferably used.
This polyethylene terephthalate multilayer laminated film is a laminated film imparted with the above-mentioned optical characteristics by alternately laminating a plurality of layers having a low refractive index and a layer having a high refractive index, for example, as a commercial product, manufactured by Teijin DuPont Tetron MLF 19.0 "," Tetron MLF 16.5 ", etc. can be used.

  On the other hand, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and acrylic, rubber-based, polyester-based, and polyurethane-based pressure-sensitive adhesives can be used. From the viewpoint of light resistance, transparency, and the like, An adhesive is preferred. The acrylic pressure-sensitive adhesive may be any of an emulsion type, a solvent type, and a solventless type, but a crosslinked type is preferable from the viewpoint of durability and the like. In this case, as the crosslinking agent, for example, a known crosslinking agent such as isocyanate, epoxy, or chelate can be used. In addition, the pressure-sensitive adhesive can contain various additives such as a tackifier, a stabilizer, and an ultraviolet absorber, as necessary, within a range that does not affect light resistance and transparency.

In the recording medium of the present invention, the resin layer having the above-mentioned optical characteristics is laminated on the heat-sensitive color forming layer, for example, depending on the layer structure of the recording medium, for example, the surface of the heat-sensitive color developing layer or the heat-sensitive color forming containing a light-absorbing heat conversion agent. It refers to laminating the resin layer on the surface of the layer or the surface of the light absorption heat conversion layer provided on the surface of the thermosensitive coloring layer. As described above, the resin layer is usually composed of a laminate film and an adhesive layer. Therefore, the resin layer is laminated by laminating the laminate film through the adhesive layer. In this case, the laminated film may be laminated one layer, or two or more layers may be laminated as necessary.
<Measurement of laser beam wavelength transmittance, visible light transmittance, and total light transmittance>
The transmittance of the resin layer (for example, laminate film / 20 μm thick adhesive layer) in the wavelength region of 400 to 1400 nm was measured with a spectrophotometer, and the transmittance of the resin layer in the laser wavelength region (800 to 1400 nm) and The transmittance peak wavelength in the wavelength region of 400 to 800 nm is examined, and the non-transmittance peak value and the total light transmittance at the wavelength are obtained.

[Adhesive layer for adherend]
In the recording medium of the present invention, an adhesive layer for attaching an adherend can be provided on the surface of the support on which the heat-sensitive color-developing layer is not provided.
The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer has a resin composition that exhibits good adhesion to an adherend and that does not inhibit this recycling when both the adherend and the recording medium are recycled as raw materials. In particular, a pressure-sensitive adhesive containing an acrylic ester copolymer as a resin component is preferable because of its excellent recyclability. In addition, rubber-based, polyester-based, polyurethane-based adhesives, and the like can also be used. Silicone-based adhesives with excellent heat resistance can also be used, but because the compatibility with the adherend is poor in the recycling process, the recycled resin tends to be non-uniform, causing strength reduction and poor appearance. May be. In addition, this pressure-sensitive adhesive may be any of emulsion type, solvent type, and solventless type, and if it is a cross-linked type, it has excellent water resistance in the washing process for repeated use of the adherend and holds the label. This is preferable for improving the durability. The thickness of the pressure-sensitive adhesive layer is usually in the range of 5 to 100 μm, preferably 10 to 50 μm.

(Peeling sheet)
In the recording medium of the present invention, a release sheet can be provided on the adherend-adhering adhesive layer as necessary. As this release sheet, if necessary, a release agent is applied to a release film substrate such as polyethylene terephthalate (PET), foamed PET, polypropylene, etc., polyethylene laminate paper, glassine paper, clay coat paper, etc. Is used. The release agent is preferably a silicone-based one, and other fluorine-based or long-chain alkyl group-containing carbamate-based ones can also be used. The application thickness of the release agent is usually in the range of 0.1 to 5.0 μm, preferably 0.2 to 3.0 μm. Moreover, although there is no restriction | limiting in particular about the thickness of a peeling sheet, Usually, it is about 10-150 micrometers.

[Production of recording medium]
In order to produce the recording medium of the present invention, for example, on one surface of the support, if necessary, an anchor coat layer, a heat-sensitive color developing layer, and if necessary, a light absorption heat conversion layer and a resin layer are provided in this order. It is preferable to provide an adhesive layer on the opposite surface of the support. The anchor coat layer, thermosensitive coloring layer, and light absorption heat conversion layer can be applied to the respective coating liquids such as direct gravure, gravure reverse, micro gravure, Meyer bar, air knife, blade, die, roll knife, reverse, curtain coat, etc. The film can be formed by coating, drying, and further heating if necessary, using a coating method such as flexographic printing, letter press, or screen printing. In particular, the thermosensitive coloring layer is desirably dried at a low temperature so as not to develop color. In the case of an ionizing radiation curable type, it is cured by irradiation with ionizing radiation.
On the other hand, the pressure-sensitive adhesive layer may be formed by directly applying and drying the pressure-sensitive adhesive on the support surface by a known method such as a roll knife coater, reverse coater, die coater, gravure coater, Meyer bar, or After the pressure-sensitive adhesive is applied to the release-treated surface of the release sheet by the above method and dried to provide a pressure-sensitive adhesive layer, it may be attached to a support and the pressure-sensitive adhesive layer transferred. The latter transfer method is preferable because the drying efficiency of the pressure-sensitive adhesive can be increased without causing color development of the thermosensitive coloring layer provided on the support.
In this way, the non-contact type recording / rewriting medium of the present invention can be obtained. FIG. 1 is an image diagram of an example of a non-contact type recording / rewriting medium of the present invention.
In the non-contact type recording / rewriting medium 10, a reversible thermosensitive coloring layer 2 and a light-absorbing heat conversion layer 3 are sequentially provided on one surface of a support 1, and further, an adhesive layer 4 is interposed therebetween. A laminate film 5 is laminated, and an adhesive layer 6 for attaching an adherend and a release sheet 7 are sequentially provided on the other surface of the support 1. Reference numeral 8 denotes an adherend.

Next, the rewriting method of the non-contact type recording / rewriting medium of the present invention will be described.
[How to rewrite recording rewritable media]
The non-contact type recording / rewriting medium rewriting method of the present invention (hereinafter, sometimes simply referred to as “rewriting method”) performs recording by irradiating the aforementioned non-contact type recording / rewriting medium of the present invention with laser light. And erasing the recording by laser light irradiation or heat treatment.
In the rewriting method of the present invention, it is preferable to use a near-infrared laser beam having a wavelength in the range of 800 to 1400 nm as the laser beam (laser beam). Those having a wavelength shorter than 800 nm are not preferable because the visibility and the readability of the optical reflection reading symbol are lowered. When the wavelength is longer than 1400 nm, the energy per pulse unit is high and the influence of heat is large, so that the heat-sensitive color developing layer and the like are gradually destroyed, and the durability of repeated recording and erasing may be reduced.

(Recording of visible information)
As a recording method in the present invention, the scanning mirror is continuously driven without oscillating the laser beam, and the locus of the laser beam (virtual laser beam) assumed when the laser beam is oscillated moves substantially at a constant speed. In this case, a recording method in which laser light is oscillated and laser light is scanned and drawn is preferable.
Further, the distance between the surface of the recording medium and the laser light source when performing recording varies depending on the scanning speed and irradiation output, but it is necessary to select the distance in consideration of character density (barcode readability) and character size. Preferably, when recording, the laser output is about 2.0 to 20 W, the irradiation distance is about 150 to 250 mm, and the duty is 50 to 100%. When erasing, the laser output is about 5 to 30 W, the irradiation distance is about 200 to 500 mm, and the duty is about 50 to 100%. The scan speed is preferably increased within a range that does not impair printing performance or erasing performance.
By irradiating only the energy required for recording with the recording laser beam in a short time, a rapid cooling effect is brought about and a good image can be obtained. Moreover, you may bring about the rapid cooling effect by ventilation of cold wind.

Of the media on which information is recorded in this manner, the recording medium having the adherend-adhering adhesive layer on the back side is affixed to the adherend manually by a machine or a person. When the machine is attached, a grid crimping method, a roller plunger method for crimping with a roll, an air blowing method with air, or the like can be employed. Further, the recording medium can be provided on the adherend not only by using an adhesive but also by any method. In this way, the adherend with the recording medium is cleaned as necessary for reuse, after fulfilling the purpose of transporting the article. As a cleaning method, a method of removing dust by blowing air, a method of washing with water, a method of cleaning with alkaline hot water, and the like are used.
In order to use the used adherend again, it is necessary to rewrite the information on the attached recording medium into new information. For this purpose, first, the recorded information is erased.

(Erase recorded information)
Examples of the method for erasing recorded information in the present invention include heating with laser light and heating with hot air, and the heating means is not particularly limited. Next, an example of the erasing method will be described.
Erasing is performed to rewrite information on the recording medium to new information. In this case, first, the recorded medium surface is irradiated with a near infrared laser beam of 800 to 1400 nm. In addition to laser light irradiation with a predetermined energy amount, the remaining rate of recorded information can be further reduced by further reducing the cooling rate by a method of contacting a hot roll or the like or a method of blowing hot air.
The heating roll can be heated to about 100 to 140 ° C., and any known heating roll can be used without particular limitation as long as it does not damage the surface of the recording medium. For example, a rubber roll, a stainless steel roll, etc. can be used. In particular, a silicone rubber roll having excellent heat resistance can be suitably used. The rubber hardness is preferably 40 degrees or more.
Also, the recorded information can be erased by blowing hot air. In this case, hot air of about 80 to 400 ° C. is blown for about 0.01 to 30 seconds. Considering the thermal deformation and erasing speed of the recording medium and the adherend, it is preferable to heat by heating hot air of 100 to 350 ° C. for an extremely short time of about 0.01 to 3 seconds.

Next, after erasing information in this way, new information is recorded by the non-contact method described above. As described above, the adherend and the recording medium can be repeatedly used by repeating the above steps.
In the present invention, the number of repetitions of recording and erasing can be 1000 times or more. The adherend and the recording medium that have been used a predetermined number of times can be sent together to the recycling process as necessary.
The non-contact type recording / rewriting medium of the present invention is, for example, a label used for the management of goods, specifically a label attached to a plastic container for transporting food, a label used for management of electronic parts, a logistics management applied to a cardboard, etc. It can be used as a label.

EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The performance evaluation of the rewritable recording medium obtained in each example was performed according to the following method.
<Recording (printing) method>
Recording was performed using a YAG laser (wavelength: 1064 nm) [trade name “LP-F10W” manufactured by Sunkus Co., Ltd.] as a laser marker for irradiation with a laser beam.
Adjust the irradiation distance 210mm, laser power 3.3W, duty 70%, scan speed 3000mm / sec, pulse period 100μs, line width 0.1mm, fill interval 0.05mm, 10 letters from alphabet A to J Was recorded.
<Erase method>
The medium was blown with hot hot air at 300 ° C. for 2 seconds from a distance of 20 mm, and then the erasability of recorded characters (the presence or absence of unerased residue) was confirmed.
<Character erasability after exposure to light>
By the recording (printing) method, the recorded sample was left for 1 month at a position 50 cm under a 4000 lux fluorescent lamp. Thereafter, the characters were erased by the above-described erasing method, the erasability was visually confirmed, and the character erasability after light exposure (hereinafter sometimes referred to as “character erasability”) was evaluated according to the following criteria.
○: Completely erased.
X: It cannot be erased completely, and character marks remain.
<Measurement of laser beam wavelength transmittance, visible light transmittance, and total light transmittance>
The transmittance of a resin layer (for example, laminate film / 20 μm thick adhesive layer) in the wavelength region of 400 to 1400 nm was measured with a spectrophotometer [manufactured by Shimadzu Corporation, model name “UV-3100PC”], The transmittance of 1064 nm, which is the wavelength of the laser light to be used, and the transmittance peak wavelength in the wavelength range of 400 to 800 nm were examined, and the non-transmittance peak value and the total light transmittance at the wavelength were determined.

Production Example 1 Preparation of Coating Liquid (Liquid A) for Formation of Thermosensitive Coloring Layer As a dye precursor, 3- (4-diethylamino-2-ethoxyphenyl) -3- (1-ethyl-2) which is a triarylmethane compound -Methylindol-3-yl) -4-azaphthalide 10 parts by mass, 30 parts by mass of 4- (N-methyl-N-octadecylsulfonylamino) phenol as reversible developer, 1.5 parts by mass of polyvinyl acetal as a binder, and As a diluent solvent, 2500 parts by mass of tetrahydrofuran was pulverized and dispersed with a pulverizer and a disper to prepare a coating solution for forming a thermosensitive coloring layer (A solution).

Production Example 2 Preparation of coating liquid for forming light absorption heat conversion layer (liquid B) Near infrared light absorption heat conversion agent (nickel complex dye) [trade name “SDA-5131” manufactured by Tosco Co., Ltd.] 100 parts by mass, ultraviolet curable binder (urethane acrylate) [manufactured by Dainichi Seika Kogyo Co., Ltd., trade name “PU-5 (NS)”] and inorganic pigment (silica) [manufactured by Nippon Aerosil Kogyo Co., Ltd., Trade name “Aerosil R-972”] 3 parts by mass was dispersed with a disper to prepare a coating liquid for forming a light absorption heat conversion layer (liquid B).

Production Example 3 Production of Adhesive Layer with Release Sheet Silicone resin [Toray Dow Corning (Toray Industries, Inc., trade name “Lumirror T-60”, manufactured by Toray Industries, Inc.] having a thickness of 100 μm. A release sheet was produced by applying a product name “SRX-211”, manufactured by Co., Ltd., so that the thickness after drying was 0.7 μm.
On the silicone resin layer of the release sheet, an acrylic pressure-sensitive adhesive [manufactured by Lintec Corporation, trade name “PA-T1”] was applied by a roll knife coater method so that the thickness after drying was 30 μm. This pressure-sensitive adhesive-coated film was dried in an oven at a temperature of 100 ° C. for 2 minutes to produce a pressure-sensitive adhesive layer with a release sheet.

Example 1
(1) Preparation of recording sample The liquid A prepared in Production Example 1 was applied to the easy-adhesion coat side of a foamed polyethylene terephthalate film [manufactured by Toyobo Co., Ltd., trade name “Chrisper 50K2411”] having a thickness of 100 μm as a support. The film was applied by a gravure method so that the thickness after drying was 4 μm, and dried in an oven at 60 ° C. for 5 minutes to form a thermosensitive coloring layer. Next, the liquid B prepared in Production Example 2 was applied on the thermosensitive coloring layer by a flexo method so that the thickness after drying was 1.2 μm, and dried in an oven at 60 ° C. for 1 minute. The light absorption heat conversion layer was produced by irradiating with ultraviolet rays at a light quantity of 220 mJ / cm ² .
The pressure-sensitive adhesive layer with a release sheet produced in Production Example 3 was bonded to the surface of the support on which the heat-sensitive color-developing layer and the light-absorbing heat conversion layer were not formed using a laminator to obtain a recording sample.
(2) Production of a rewritable recording medium A laminate film “Tetron MLF 16.5” (hereinafter referred to as laminate film (a)) made by Teijin DuPont with a thickness of 16.5 μm is used as a laminate film. As the cross-linked pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive [manufactured by Lintec Co., Ltd., trade name “PL Thin”] was applied so that the coating thickness after drying was 20 μm. The laminate material thus obtained was laminated on the upper layer (light absorption heat conversion layer surface) of the previous recording sample to prepare a rewritable recording medium.
With respect to the laminate material (laminate film (a) / adhesive layer having a thickness of 20 μm), the transmittance at 1064 nm, which is the wavelength of the laser beam, the non-transmittance peak wavelength, the non-transmittance peak value at this wavelength, and the total light transmittance And erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Example 2
The same operation as in Example 1 was performed except that a laminate film “Tetron MLF 19.0” (hereinafter referred to as a laminate film (b)) manufactured by Teijin DuPont was used as the laminate film. A rewritable recording medium was produced.
Regarding the laminate material (laminate film (b) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm, which is the wavelength of the laser beam, the non-transmittance peak wavelength, the non-transmittance peak value at the wavelength, and the total light transmittance, The erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Example 3
A rewritable recording medium was produced in the same manner as in Example 1 except that two laminates (a) were laminated and laminated as a laminate film.
For the laminate material (laminate film (a) / 20 μm pressure-sensitive adhesive layer / laminate film (a) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm which is the wavelength of the laser beam, the non-transmittance peak wavelength and the non-transmittance at the wavelength The peak value and total light transmittance were determined, and the erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Example 4
A rewritable recording medium was produced in the same manner as in Example 1 except that the laminate film (b) was laminated and laminated as a laminate film.
For the laminate material (laminate film (b) / 20 μm pressure-sensitive adhesive layer / laminate film (b) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm which is the wavelength of the laser beam, the non-transmittance peak wavelength and the non-transmittance at the wavelength The peak value and total light transmittance were determined, and the erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Example 5
A laminate film “Tetron MLF13.0” (hereinafter referred to as a laminate film (c)) manufactured by Teijin DuPont as a laminate film and the laminate film (a) are combined with the laminate film (a A rewritable recording medium was produced by performing the same operation as in Example 1 except that the laminate was laminated so that the upper side of the film was on the upper side.
For the laminate material (laminate film (a) / 20 μm pressure-sensitive adhesive layer / laminate film (c) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm, which is the wavelength of the laser beam, the non-transmittance peak wavelength, and the non-transmittance at the wavelength The peak value and total light transmittance were determined, and the erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Example 6
A rewritable recording medium is obtained by performing the same operation as in Example 1 except that the laminate film (a) and the laminate film (b) are laminated and laminated so that the laminate film (b) is on the upper side as the laminate film. Was made.
Regarding the laminate material (laminate film (b) / 20 μm pressure-sensitive adhesive layer / laminate film (a) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm which is the wavelength of the laser beam, the non-transmittance peak wavelength and the non-transmittance at the wavelength The peak value and total light transmittance were determined, and the erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Example 7
A rewritable recording medium is operated in the same manner as in Example 1 except that the laminate film (c) and the laminate film (b) are laminated and laminated so that the laminate film (b) is on the upper side as the laminate film. Was made.
Regarding the laminate material (laminate film (b) / 20 μm pressure-sensitive adhesive layer / laminate film (c) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm which is the wavelength of the laser beam, the non-transmittance peak wavelength and the non-transmittance at the wavelength The peak value and total light transmittance were determined, and the erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Comparative Example 1
A rewritable recording medium was prepared in the same manner as in Example 1 except that a film “Lumirror 25T61M” (hereinafter referred to as laminate film (d)) manufactured by Toray Industries, Inc. having a thickness of 25 μm was laminated as the laminate film. Produced.
For the laminate material (laminate film (d) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm, which is the wavelength of the laser beam, the non-transmittance peak wavelength, the non-transmittance peak value at this wavelength, and the total light transmittance, The erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Comparative Example 2
A rewritable recording medium was produced in the same manner as in Example 1 except that the laminate film (c) was laminated as the laminate film.
Regarding the laminate material (laminate film (c) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm, which is the wavelength of the laser beam, the non-transmittance peak wavelength, the non-transmittance peak value at the wavelength, and the total light transmittance, The erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

Comparative Example 3
A rewritable recording medium was produced in the same manner as in Example 1 except that two layers of laminate (c) were laminated as a laminate film.
For the laminate material (laminate film (c) / 20 μm pressure-sensitive adhesive layer / laminate film (c) / 20 μm pressure-sensitive adhesive layer), the transmittance of 1064 nm which is the wavelength of the laser beam, the non-transmittance peak wavelength and the non-transmittance at the wavelength The peak value and total light transmittance were determined, and the erasability of the rewritable recording medium was evaluated. The results are shown in Table 1 and FIG.

The laminate materials in Examples 1 to 4 have a peak value of 67 to 81% of maximum opacity in the wavelength range of 500 to 700 nm, and Example 5 has 64% and 68% at wavelengths of 450 nm and 550 nm, respectively. The non-transmittance peak value, Example 6 has a non-transmittance peak value of 68% at wavelengths of 550 nm and 620 nm, and Example 7 has a non-transmittance peak value of 64% at wavelengths of 450 μm and 620 μm, respectively. is doing. The rewritable recording mediums of the present invention of Examples 1 to 7 formed by laminating laminate materials having such optical characteristics are all acceptable in character erasability.
On the other hand, the laminate material in Comparative Example 1 does not have an opacity peak in the wavelength range of 500 to 700 nm, and Comparative Example 2 has an opacity peak value of 62% at a wavelength of 450 nm. There is no non-transmittance peak in the wavelength region of 700 nm. Further, the laminate material in Comparative Example 3 has an opacity peak value of 82% at a wavelength of 450 nm, but does not have an opacity peak in the wavelength region of 500 to 700 nm.
The rewritable recording media of Comparative Examples 1 to 3 formed by laminating laminate materials having such optical characteristics have a character erasability of “x” and fail.
In addition, the laser beam (wavelength 1064nm) transmittance | permeability of the laminate material in Examples 1-7 and Comparative Examples 1-3 was all 80% or more. Moreover, all the light transmittances of the laminate materials in Examples 1 to 7 and Comparative Examples 1 to 3 were all 70% or more.

  The non-contact type recording / rewriting medium of the present invention is capable of recording / erasing visible information in a non-contact manner with a laser beam, is excellent in light resistance, can suppress a decrease in erasability of recorded information with time, and records information For example, labels used for the management of goods, specifically labels for plastic containers that transport food, labels for management of electronic components, logistics management labels for cardboard, etc. It is suitable as.

DESCRIPTION OF SYMBOLS 1 Support body 2 Reversible thermosensitive coloring layer 3 Light absorption heat conversion layer 4 Adhesive layer 5 Laminate film 6 Adhesive layer for adherend adherend 7 Release sheet 8 Adherent 10 Non-contact type recording / rewriting medium

Claims (7)

  A non-contact type recording / rewriting medium in which a reversible thermosensitive coloring layer is provided on one surface of a support, and the visible information is rewritten in a non-contact manner with a laser beam, on the reversible thermosensitive coloring layer, 500 A non-contact type recording / rewriting medium, wherein a resin layer having at least one non-transmittance peak is laminated in a visible light region of ˜700 nm.   2. The non-contact type recording / rewriting medium according to claim 1, wherein a peak value of maximum non-transmission in a visible light region of 500 to 700 nm is in a range of 40 to 98%.   The non-contact type recording / rewriting medium according to claim 1, wherein the total light transmittance in a visible light region of 400 to 800 nm is 70% or more.   The non-contact type according to any one of claims 1 to 3, wherein the wavelength of the laser beam to be used is in the range of 800 to 1400 nm, and the transmittance of the laser beam at the wavelength of the laser beam of the resin layer is 80% or more. Recording rewritable medium.   The non-contact type recording / rewriting medium according to claim 1, wherein the resin layer comprises a laminate film and an adhesive layer.   The non-contact type recording / rewriting medium according to claim 5, wherein the laminate film is a polyethylene terephthalate multilayer laminated film.   A non-contact type recording rewritable medium according to any one of claims 1 to 6, wherein recording is performed by irradiating a laser beam, and the recording is erased by irradiation with a laser beam or heat treatment. A method for rewriting a contact-type recording / rewriting medium.

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