JP2003312143A - Information recording medium - Google Patents

Abstract

(57) [Summary] [Problem] It is possible to improve visibility without causing glare and the like, and to prevent rewriting repetition operation.
To provide a reversible information recording medium which does not cause physical deterioration and has excellent rewrite durability. SOLUTION: The information recording medium is an information recording medium having a reversible recording layer on a base material, which reversibly displays a visible image or erases a visible image depending on temperature, and is adjacent to the reversible recording layer. A layer mainly composed of nickel and / or chromium is provided on the substrate side, and a protective layer is provided on the side of the reversible recording layer opposite to the layer mainly composed of nickel and / or chromium. Have been. Here, the layer containing nickel and / or chromium as a main component is preferably formed by vapor deposition.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording medium capable of displaying and erasing a visible image by heat or light. 2. Description of the Related Art In a rewritable recording medium, a thermal head capable of controlling heating in dot units has been used as an image recording means. Further, as an image erasing means, a thermal head, a heater bar or a heating stamp capable of erasing the entire area has been used.
In this case, printing or erasing is performed on the rewritable recording medium by heating an image recording unit or an image erasing unit such as a thermal head by directly contacting the surface of the rewritable recording medium. Even if a protective layer is provided on the surface, only a layer of about several μm can be provided from the viewpoint of image recording and erasing. In the operation of rewriting information on the rewrite recording medium,
Heat, pressure, elasticity, abrasion, etc. are applied to the surface of the rewritable recording medium. Therefore, the surface of the recording medium is physically deteriorated, and there is a limit to the number of times of repeated use of information rewriting. Therefore, in order to prevent physical deterioration, it is considered effective to form a visible image without irradiating the surface of the rewritable recording medium with laser light,
Development of a rewritable recording medium corresponding thereto has been promoted, and a rewritable recording medium having a reversible recording layer for displaying a visible image reversibly or erasing a visible image depending on temperature has been proposed. However, in order to enhance the visibility of a visible image, aluminum is often deposited on the back surface of the reversible recording layer. In a rewritable recording medium having a reversible recording layer on which aluminum is deposited on the back side, glare occurs because the glossiness of aluminum is too strong. Further, the visibility may be reduced depending on the light reflection state. For this reason, there has been a demand for a means capable of improving visibility without causing glare or the like. In addition, there is a problem that it is easily corroded by an acid or an alkali. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve visibility without causing glare and the like.
It is another object of the present invention to provide a reversible information recording medium which does not cause physical deterioration due to repeated rewrite operations and has excellent rewrite durability and chemical resistance. An information recording medium according to the present invention has an information recording medium having, on a base material, a reversible recording layer for displaying a visible image reversibly or erasing a visible image depending on temperature. A layer containing nickel and / or chromium as a main component is provided on the substrate side adjacent to the reversible recording layer, and the nickel and / or chromium is mainly contained in the reversible recording layer. It is characterized in that a protective layer is provided on the side opposite to the layer as a component. DESCRIPTION OF THE PREFERRED EMBODIMENTS The information recording medium of the present invention has a reversible recording layer on a substrate, and is provided on the back surface of the reversible recording layer, ie, between the substrate and the reversible recording layer. A layer mainly composed of nickel and / or chromium, which functions as an optical reflection surface, is provided in order to increase the contrast of visible information and improve sharpness. Here, nickel and / or chromium refers to nickel, chromium, an alloy of nickel and chromium, and the like. The layer containing nickel and / or chromium as a main component (hereinafter, also referred to as “metal layer”) constituting the information recording medium of the present invention may contain other components. And chrome alloy 5
It is preferably contained at 0 atomic% or more, more preferably at 70 atomic% or more. The metal layer according to the present invention is preferably provided by vapor deposition, but a thin film containing nickel and / or chromium as a main component capable of achieving the object of the present invention is formed on the back side of the reversible recording layer. If it can be done, it is not limited to those formed by vapor deposition. [0008] Instead of the aluminum layer provided as a light reflection layer on the conventional information recording medium, nickel and / or
Alternatively, in the information recording medium of the present invention provided with a metal layer containing chromium as a main component, a layer below the metal layer, here, the base material surface can be seen through (semi-transparent). It is also possible to give a subtle hue by overlapping colors, or to give a three-dimensional design or the like by seeing through the metal layer a pattern or the like on the substrate surface, which is excellent from the viewpoint of design. In addition, an information recording medium having a layer made of aluminum has a glare, but an information recording medium having a layer containing nickel and / or chromium as a main component does not give a glare. Further, nickel and chromium are less likely to be corroded by acids and alkalis than aluminum, so that deterioration of the light reflecting layer can be suppressed and visibility can be prevented from lowering. Here, the substrate may be a single layer or a laminate of two or more layers, but is preferably made of at least one layer of a plastic film. Further, the plastic film is preferably transparent. As the base material, for example, vinyl chloride, acrylonitrile-butadiene-styrene copolymer (ABS), polycarbonate (PC), crystalline polyester, amorphous polyester,
Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyetherimide (PE
Synthetic resins such as I), polyimide (PI), and polyetheretherketone (PEEK). The reversible recording layer formed on the metal layer of the base material may be formed by coating or the like, or may be laminated via an adhesive layer such as hot melt. Therefore, the thickness of the reversible recording layer can be made thicker or thinner, and is appropriately selected and formed in the range of 1 μm to 100 μm according to the application. The reversible recording layer can display or erase a visible image reversibly by temperature or light. As the reversible recording layer, by adjusting the heating temperature, a transparent state or a cloudy state is changed to a visible state, and by adjusting the heating temperature and the cooling rate after heating, the color is developed and erased. Any of those that become visible can be used. Examples of the former case include those in which a crystalline organic low-molecular compound is dispersed in a polymer resin base material, and examples of the latter include an electron-donating color substance in a polymer resin base material. One in which an electron-accepting compound is dispersed is exemplified. First, by adjusting the heating temperature,
A material that changes to a transparent state or a cloudy state (hereinafter, referred to as a “transparent cloudy type” in the present specification) will be described. As the polymer resin base material used for the transparent opaque type, a synthetic resin which is transparent and has good film-forming properties is preferable. For example, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer is preferable. Copolymer, vinyl chloride-vinyl acetate-acrylic acid copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, other vinyl acetate compounds, vinyl chloride copolymer, polyvinylidene chloride, vinylidene chloride copolymer, polyester Resin, polyurethane resin, acrylic resin, polystyrene resin, AB
Transparent amorphous resin such as S resin and AS resin may be used. These may be used alone or as a mixture of two or more. When a radiation curable resin which is cured by irradiating an electron beam or an ultraviolet ray or the like to a polymer resin base material is mixed, the elastic modulus in a high temperature region is increased, and the rewrite durability is improved. it can. Examples of such a radiation-curable resin include polyfunctional acrylate monomers having excellent curability such as tetraethylene glycol diacrylate and trimethylolpropane triacrylate. In the case of an ultraviolet curable resin, an appropriate amount of a benzoin-based, acetophenone-based, thioxanthone-based, or peroxide-based photopolymerization initiator is added and cured. The low-molecular organic compound to be dispersed in the polymer resin base material may be 0.1 to 2.0 μm in the polymer resin base material.
Those which are dispersed as aggregates having a diameter of about the same and which melt or crystallize by heat treatment are preferably used. Examples of such organic low-molecular compounds include compounds composed of carboxylic acids, dicarboxylic acids, ketones, ethers, alcohols, esters and derivatives thereof, and these may be used alone or as a mixture of two or more. You may use it. In the present invention, it is preferable to use a fatty acid alkyl ester having a main chain of 12 or more carbon atoms. Fatty acid alkyl esters having a main chain of 12 or more carbon atoms are low melting point (mp.) Compounds and are preferably used because they are melted and crystallized by heat treatment at a relatively low temperature. It is more preferable to use a combination of a fatty acid alkyl ester having a main chain of 12 or more carbon atoms and an aliphatic dibasic acid having a high melting point (mp.) Of 10 or more carbon atoms. By adjusting and using the mixing ratio of the fatty acid alkyl ester and the aliphatic dibasic acid, it is possible to adjust the temperature range in which transparency is achieved, and to change the degree of transparency and cloudiness at a predetermined temperature. Is possible. Examples of the fatty acid alkyl ester having a main chain of 12 or more carbon atoms include methyl stearate, ethyl stearate, butyl stearate, octyl stearate, stearyl stearate, behenyl stearate,
Examples include methyl behenate, ethyl behenate, butyl behenate, octyl behenate, stearyl behenate, behenyl behenate, methyl lignocerate, ethyl lignocerate, stearyl lignocerate, and behenyl lignocerate. Examples of the aliphatic dibasic acid having 10 or more carbon atoms include sebacic acid, dodecane diacid, tetradecane 2
Acid, eicosane diacid and the like. Main chain has 12 carbon atoms
The above fatty acid alkyl esters and aliphatic dibasic acids having 10 or more carbon atoms may be used alone or as a mixture of two or more. The mixing ratio of the polymer resin base material and the organic low molecular weight compound is preferably 10 to 100 parts by weight, more preferably 20 to 100 parts by weight, based on 100 parts by weight of the polymer resin base material. More preferably, it is 50 parts by mass. Next, a reversible recording material whose color tone can be reversibly changed by adjusting the heating temperature and the cooling rate after heating (hereinafter referred to as "color tone change type" in the present specification) will be described. Examples of the color change type include those in which an electron donating color compound and an electron accepting compound are dissolved or dispersed in a polymer resin base material. Examples of the electron-donating color compound include so-called leuco dyes having a lactone ring in the molecular structure. Examples of the leuco dye include crystal violet lactone, 3- (4-diethylamino-2-)
Phthalide compounds such as ethoxyphenyl) -3- (1-ethyl-2-methylindol-3-yl) -4-azaphthalide and 3,3-bis (1-ethyl-2-methylindol-3-yl) phthalide; 3-diethylamino-6
Methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-7-anilinofluoran, 2- (2-chloroanilino) -6-diethylaminofluoran, 2-
(2-chloroanilino) -6-dibutylaminofluoran, 2-anilino-3-methyl-6 (N-ethylisopentylamino) fluoran, 3-cyclohexylmethylamino-6-methyl-7-anilinofluoran, 3 -Benzylethylamino-6-methyl-7-anilinofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-methylpropylamino-6-methyl-
Fluorane compounds such as 7-anilinofluoran and 3-diethylamino-6-methyl-7-xylidinofluoran are preferred. These compounds have a lactone ring moiety in the molecular structure, and the lactone ring develops or decolors when it opens or closes. Examples of the electron-accepting compound include an organic phosphoric acid compound having an aliphatic group having 6 or more carbon atoms, an aliphatic carboxylic acid compound, and a phenolic compound (a phenolic compound having an aliphatic group having 12 or more carbon atoms). preferable)
Is mentioned. Specific examples of the electron accepting compound include, for example, dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonic acid, octadecylphosphonic acid, eicosylphosphonic acid, α-hydroxydecanoic acid, α-hydroxytetradecanoic acid, α-hydroxyhexadecane Acid, α-hydroxyoctadecanoic acid, α-hydroxypentadecanoic acid, α-hydroxyeicosanoic acid, α-hydroxydocosanoic acid, α-hydroxytetracosanoic acid, α
-Hydroxyhexacosanoic acid, α-hydroxyoctacosanoic acid and the like. As phenolic compounds,
For example, 4'-hydroxy-4-octadecylbenzanilide, N-octadecyl-4-hydroxybenzamide, N- (4-hydroxyphenyl) -N'-octadecylurea, 4-hydroxyphenylpropiono-behenylhydrazide and the like can be mentioned. Examples of the polymer resin base material used here include a polymer composed of a resin serving as a base material and a crosslinking agent for crosslinking the resin. As a crosslinking agent, an isocyanate compound is generally used. As a resin serving as a base material, a thermoplastic resin having good transparency and film forming properties and high heat resistance is used. It is preferable to use a thermoplastic resin having a hydroxyl group, an amino group, a carboxyl group, or the like that thermally crosslinks with the isocyanate crosslinking agent, and it is particularly preferable to use a thermoplastic resin such as an acrylic polyol, a polyester polyol, or a polyurethane polyol. As the isocyanate crosslinking agent, hexamethylene diisocyanate, toluene diisocyanate and the like are preferably used. The mixing ratio of the leuco dye, the electron-accepting compound and the polymer resin base material is based on 10 parts by mass of the leuco dye.
The amount of the electron-accepting compound is preferably 10 to 100 parts by mass, more preferably 20 to 50 parts by mass.
The resin base material is preferably 10 to 200 parts by mass, more preferably 20 to 100 parts by mass with respect to parts by mass. However, the polymer resin base material herein includes a resin serving as a base material and an isocyanate compound appropriately blended in accordance with the OH value thereof. The reversible recording layer is formed by dispersing an organic low-molecular compound in a polymer resin base material and then coating it on a metal layer such as a card base, or by providing an electron donor in the polymer resin base material. It is formed by dissolving or dispersing a chromatic coloring compound and an electron-accepting compound, and then applying the solution on a metal layer such as a card substrate. In the present invention, the reversible recording layer may contain a light-to-heat conversion material, or may be provided with a layer containing a light-to-heat conversion material adjacent to the reversible recording layer (hereinafter referred to as "light-to-heat conversion layer"). . Since the light-to-heat conversion material is expensive, by providing the light-to-heat conversion layer adjacent to the reversible recording layer, the thickness of the light-to-heat conversion layer can be reduced and the cost can be reduced. In addition, if the recording layer contains a light-to-heat conversion material, the recording characteristics may be adversely affected, but if the light-to-heat conversion layer is provided adjacent to the recording layer, the recording layer does not contain the light-to-heat conversion material. Therefore, such adverse effects do not occur. Examples of the light-to-heat conversion substance to be used include an infrared absorbing dye and carbon black, and those having an absorption peak near the oscillation wavelength of the semiconductor laser light to be used are selected. Generally, a wavelength of 100 nm to 1,000
A semiconductor laser having a wavelength of 0 nm, preferably 700 to 900 nm can be used. As the infrared absorbing dye, a cyanine dye, a polymethine dye, an anthraquinone dye having an absorption peak in such a wavelength region is preferably used. Of these, phthalocyanine dyes or naphthalocyanine dyes are preferred. Structurally, it is durable against degradation such as decomposition by heat or ultraviolet rays, so that the number of rewrites can be improved. Weatherability,
From the viewpoint of chemical stability such as heat resistance, those which form a complex with various metals are particularly preferable. In the information recording medium of the present invention, it is preferable to provide a protective layer on the outermost layer, and it is preferable to provide a protective layer on at least the reversible recording layer. When the protective layer covering the reversible recording layer is made of a transparent plastic film, an ultraviolet curable resin, or the like, the visible portion of the reversible recording layer can be externally observed through the transparent protective layer. Further, in the case of a transparent plastic film, printing can be performed on the back side, so that printing is not exposed and printing durability is improved. Here, since the transparent protective layer has a sufficient thickness, even if contact or abrasion occurs, the visualized portion is protected by the transparent sheet and has excellent rewrite durability. Further, since the reversible recording layer shields ultraviolet rays with a transparent protective layer on the surface, deterioration of ultraviolet rays is prevented. In the information recording medium of the present invention, a magnetic recording layer is formed on one surface of a base material, and a metal such as nickel or chromium, or an alloy of nickel and chromium is vapor-deposited on the other surface. A reversible recording layer is formed. Further, it is preferable to form a protective layer thereon. Thus, an information recording medium according to the first embodiment of the present invention having the magnetic recording layer, the base material, the metal layer, the reversible recording layer, and the protective layer in this order is obtained. Although the thickness of each layer constituting the information recording medium of the present invention is not particularly limited, the thickness of the protective layer is preferably 1 to 200 μm from the viewpoint of protection of the reversible recording layer and the like. The thickness of the substrate such as plastic film is 25
μm to 1,000 μm, and the reversible recording layer is 1 to 10 μm.
0 μm, and the thickness of the metal layer is preferably 0.01 μm to 2 μm. This is because if the thickness of the reversible recording layer is within this range, the contrast of a visible image can be obtained, and the speed of image printing and erasing can be satisfied. In the present invention, additives and the like can be appropriately added to each layer constituting the information recording medium. Plastic film as a base material, if necessary,
A surface treatment such as a corona treatment and an easy-adhesion coat may be appropriately performed. For example, when an information recording medium is used as a card or label, it is often printed,
It is preferable to perform a surface treatment. Further, a magnetic recording layer, an IC chip, or the like may be mounted for higher functionality. The information recording medium of the present invention is, for example, a point card, a prepaid card, a credit card, an ID card.
It is suitable for cards such as cards, container labels for distribution, and the like. The information recording medium of the present invention can be made visible by using a laser. A commonly used laser can be used. EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples. (Example 1) On the back surface of a transparent polyethylene terephthalate film having a thickness of
The magnetic recording layer is formed by applying a coating so as to have a thickness of 0 μm. On the other surface of the polyethylene terephthalate film, nickel was deposited to a thickness of 0.7 μm to form a metal layer. On the metal layer, 300 parts by mass of a vinyl chloride-vinyl acetate copolymer and 8 parts of lauron were added.
A coating solution prepared by dissolving 0 parts by mass and 20 parts by mass of dodecane diacid in tetrahydrofuran was applied, and dried by heating at 110 ° C. for 5 minutes to form a reversible recording layer having a thickness of 10 μm. Next, a PET film having a thickness of 2 μm is laminated as a protective layer on the formed reversible recording layer using a urethane-based adhesive, and then over the protective layer so as to form a visible recording display window. Printed. Further, an ultraviolet curable resin having a thickness of 3 μm was laminated as a protective layer on the magnetic recording layer on the back side of the substrate. This was punched out into a card shape to produce a card-shaped information recording medium. The obtained card-shaped information recording medium was evaluated and tested as described below. << Evaluation Method and Test Method >> (1) Evaluation of Visibility After the information recording medium is heated at a temperature of 80 ° C. for 1 minute, it is cooled to room temperature to make it transparent. This transparent card-shaped information recording medium is printed by using a rewrite rewriting device under the condition that the applied energy is 0.35 mJ / dot, and the visibility of the characters is visually evaluated. However, the evaluation criterion is represented by the symbol “○” for those having good visibility without glare and the symbol “x” for those having glare and poor visibility. (2) Evaluation of Acid Resistance The information recording medium was immersed in a 5% HCl aqueous solution for 24 hours, and the appearance of the information recording medium was visually observed. However,
The evaluation criterion is indicated by a symbol “○” when the appearance of the information recording medium is good, and by a symbol “×” when there is a problem such as deterioration of the end of the card-shaped information recording medium. (3) Evaluation of alkali resistance An information recording medium in the form of a card was immersed in a 5% aqueous sodium carbonate solution for 24 hours, and the appearance of the card was visually observed. However, the evaluation criterion is represented by a symbol “○” when the appearance of the card is good, and a symbol “×” when there is a problem such as deterioration of the end of the card. (Example 2) A card-shaped information recording medium was prepared in the same manner as in Example 1, except that chromium was vapor-deposited instead of nickel as a metal layer on the base material. The same evaluation as in Example 1 was performed on the obtained card-shaped information recording medium. Table 1 shows the results. Comparative Example 1 A card-shaped information recording medium was produced in the same manner as in Example 1 except that aluminum was vapor-deposited instead of nickel as a metal layer on the base material. The same evaluation as in Example 1 was performed on the obtained card-shaped information recording medium. Table 1 shows the results. [Table 1] As is apparent from Table 1, it was found that Examples 1 and 2 in which nickel or chromium was deposited as the metal layer had no glare or the like on the background of the characters and had excellent visibility. Examples 1 and 2 were also found to be excellent in acid resistance and alkali resistance. On the other hand, Comparative Example 1
Has aluminum deposited as a metal layer,
It was found that the background was glaring and the visibility was poor in reading the characters. Further, in the evaluation of acid resistance and alkali resistance, it was found that when the information recording medium was immersed in an acidic solution or an alkaline solution, the end portion was deteriorated, and both the acid resistance and the alkali resistance were inferior. As described above, according to the present invention,
It is possible to provide a reversible information recording medium that can improve visibility without causing glare and the like, and does not cause physical deterioration in repeated rewrite operations and has excellent rewrite durability. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B41M 5/18 F 5/26 102 (72) Inventor Tomohiko Terai 5-8 Mitsuyacho, Nagahama-shi, Shiga Mitsubishi Resin F-term in Nagahama Plant (reference) 2H026 AA07 AA09 BB01 DD01 DD32 DD57 FF15 HH00 2H111 HA07 HA18 HA23 HA34 HA35 5D029 LA13 LB04 LC01 LC21

Claims (1)

Claims: 1. An information recording medium having a reversible recording layer on a base material for displaying a visible image reversibly or erasing a visible image depending on temperature, wherein the reversible recording layer is provided. A layer containing nickel and / or chromium as a main component is provided on the base material side adjacent to the substrate, and the reversible recording layer is provided on a side opposite to the layer containing nickel and / or chromium as a main component. An information recording medium provided with a protective layer.