JP3226670B2 - Pressure-sensitive material having reversibility and reversible pressure-sensitive recording medium using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible pressure-sensitive material in which the transparency changes by pressure means such as a dot impact printer, handwriting, and a stamp, and the transparency returns to the state before pressurization by heat. The present invention relates to a reversible pressure-sensitive recording medium using the same.

[0002]

2. Description of the Related Art As a general method for recording character information and image information, there is a method using a handwritten method and an apparatus. Specific examples of the former include: a method of recording characters or the like on paper with a pencil, a ballpoint pen, ink, or the like;
No. 40376, JP-A-50-142476,
A method using pressure-sensitive copying paper using microcapsules as described in JP-A-51-14179,
: There is a method using a blackboard or a whiteboard using wiping ink. The latter (using equipment)
As a specific example, there is an image forming apparatus such as a printer or a plotter of a type using toner or thermal paper.

[0003] In recent years, a display plate is made of a reversible thermosensitive recording material, and characters are recorded by selectively applying heat to the display plate. Such a reversible thermosensitive recording material is considered to be applied as a recording medium such as a printer or a facsimile using a thermal head.

[0004]

However, in the above-mentioned conventional recording methods, the method of recording on paper, the method of using toner, and the method of using thermal paper, when the information once recorded is no longer necessary, is recorded. The paper itself will be discarded. In the information and communication era such as today, the amount of recording paper discarded is enormous, and improvement in resource saving is desired.

In the above-described conventional recording method using a blackboard or whiteboard, a blackboard or whiteboard can be used many times by using a chalk or a predetermined pen and a blackboard eraser (board eraser). When using a blackboard, there is a problem that clothes and the like are stained by chalk powder and the human body is contaminated, and when using a whiteboard, the written characters can be erased cleanly when erasing the board. There is a problem that the character does not exist, and a character is blurred when the solvent in a predetermined pen evaporates.

A reversible thermosensitive recording material is suitable for a printer or a facsimile using a thermal head. However, heat is required for printing. Special input means such as a pen is required. Therefore, there is a problem that it is disadvantageous in terms of safety and reduction of apparatus cost.

[0007] The present application has been made in view of such a point. Therefore, an object of the first invention of the present application is to provide a material which can be used repeatedly by reversibly performing information writing by pressure and information erasing by heat. Is to provide. Another object of the second invention of this application is to provide a reversible pressure-sensitive recording medium using the material of the first invention.

[0008]

In order to achieve this object, according to the pressure-sensitive material having reversibility of the first invention, a matrix material mainly composed of polyvinyl acetal and a matrix material mixed with the matrix material are used. , And one or more organic low-molecular substances selected from esters and ketones, and the mixing ratio (weight ratio) between the matrix material and the organic low-molecular substances is 1: 2
It is characterized by a range of 20: 1.

Here, the mixing ratio between the matrix material and the organic low-molecular substance is the weight ratio of the latter. If the mixing ratio is more than 1: 2, it becomes difficult to form a reversible pressure-sensitive material.
If it is less than 1, the pressure sensitivity is reduced, so that 1: 2-
It is preferred to be in the range of 20: 1.

[0010] The term "matrix material" and "one or more organic low-molecular substances selected from esters and ketones" mixed with the matrix material as used herein include, of course, the case where only these are used. In addition to these, it also means a case where other substances such as a substance improving the film quality of the pressure-sensitive material and a substance improving the lubricity are included.

[0011]

Further, in the first invention, polyvinyl acetal is used as the main material: when the matrix material is composed of only the resin, it is obtained by mixing the resin with the main material and other substances. Any of the cases where a matrix material is formed can be used. Examples of the other substance to be mixed with the main material include one or more of a phenol resin, an epoxy resin, an epoxy compound, an aldehyde compound, and an isocyanate compound.

The one or more organic low-molecular substances selected from esters and ketones referred to in the first invention are:
In the case where one type is selected and used, any case where two or more types are selected and used as a mixture is good. Here, specific examples of the one or more organic low-molecular substances selected from esters and ketones in the first invention include the following.

First, as esters, palmitic acid n
Hexadecyl, vinyl stearate, phenyl stearate, phenone stearate, n-dodecyl stearate, stearyl stearate, methyl arachidate, methyl behenate, stearyl linoleate, decyl octacosanoate, undecyl octacosanoate, dodecyl octacosanoate, tridecyl octacosanoate , Tetradecyl octacosanoate, pentadecyl octacosanoate, hexadecyl octacosanoate, heptadecyl octacosanoate, octadecyl octacosate, methyl decanoate, methyl undecanoate, methyl dodecanoate, methyl tridecanoate, methyl tetradecanoate, methyl pentadecanoate, methyl hexadecanoate, heptadecane Methyl, methyl octadecanoate, methyl nonadecanoate, methyl eicosanoate, methyl henicosanoate , Methyl docosanoate, methyl tricosanoate, methyl tetracosanoate, methyl pentacosanoate, methyl hexacosanoate, methyl heptacosanoate, methyl octacosanoate, methyl nonakosanate, methyl triacontanate, methyl hentriacontanate, methyl dotriacontanate, Methyl tritriacontanate, methyl tetratriacontanate, methyl pentatriacontanate, methyl hexatriacontanate, methyl heptatriacontanate, methyl nonatriacontanate, methyl tetracontanate, methyl hentetracontanate, dotetracontan Methyl acrylate, methyl tritetraacontanate, methyl tetratetracontanate, methyl pentatetracontanate, methyl hexatetracontanate, methyl heptatetracontanate, octatetra Methyl pentanate, methyl nonatetracontanate, methyl pentacontanate, methyl hempetacontanate, methyl dopentacontanate, methyl tripentacontanate, methyl tetrapentacontanate, methyl pentapentacontanate, methyl hexapentacontanate , Methyl heptapentacontanate, methyl octapentacontanate, methyl nonapentacontanate, methyl hexacontanate, methyl dohexacontanate, methyl decenoate, methyl undecenoate, methyl dodecenoate, methyl tridecenoate, methyl tetradecenoate, Methyl pentadecenoate, methyl hexadecenoate, methyl heptadecenoate, methyl octadecenoate, methyl nonadecenoate, methyl eicosenoate, methyl heneicosenoate, methyl docosenate, methyl tricosenate, te Methyl trachosenate, methyl pentacosenoate,
Methyl hexacosenoate, methyl heptacosenoate, methyl octacosenoate, methyl nonakosenoate, vinyl decanoate, vinyl undecanoate, vinyl dodecanoate, vinyl tridecanoate, vinyl tetradecanoate, vinyl pentadecanoate, vinyl hexadecanoate, vinyl heptadecanoate,
Vinyl octadecanoate, vinyl nonadecanoate, vinyl eicosanoate, vinyl heneicosanoate, vinyl docosanoate, vinyl tricosanoate, vinyl tetracosanoate, vinyl pentacosanoate, vinyl hexacosanoate, vinyl heptacosanoate, vinyl octacosanoate, vinyl nonakosanoate, triacontan Vinyl acrylate, vinyl hentriacontanate, vinyl dotriacontanate, vinyl tritriacontanate, vinyl tetratriacontanate, vinyl pentatriacontanate, vinyl hexatriacontanate,
Vinyl heptatricontanate, vinyl nonatricontanate, vinyl tetracontanate, vinyl henetetracontanate, vinyl dotetracontanate, vinyl tritetraacontanate, vinyl tetratetracontanate, vinyl pentatetracontanate, hexatetra Vinyl contanate, vinyl heptatetracontanate, vinyl octatetracontanate, vinyl nonatetracontanate, vinyl pentacontanate, vinyl hempetacontanate, vinyl dopentacontanate, vinyltripentacontanate,
Vinyl tetrapentacontanate, vinyl pentapentacontanate, vinyl hexapentacontanate, vinyl heptapentacontanate, vinyl octapentacontanate,
Vinyl nonapentacontanate, vinyl hexacontanate, vinyl dohexacontanate, vinyl decenoate, vinyl undecenoate, vinyl dodecenoate, vinyl tridecenoate, vinyl tetradecenoate, vinyl pentadecenoate, vinyl hexadecenoate, vinyl heptadecenoate, octadecene Vinyl acrylate, vinyl nonadecenoate, vinyl eicosenoate, vinyl heneicosenoate, vinyl docosenoate, vinyl tricosenoate, vinyl tetracosenoate, vinyl pentacosenoate, vinyl hexacosenoate, vinyl heptacosenoate, vinyl octacocene, vinyl nonaconate, phenyl decanoate Phenyl undecanoate, phenyl dodecanoate, phenyl tridecanoate, phenyl tetradecanoate, phenyl pentadecanoate, phenyl hexadecanoate, and heptadecanoate Phenyl, octadecanoate, phenyl nonadecanoate, phenyl eicosanoate, phenyl heneicosanoate, phenyl docosanoate, phenyl trichosanoate, phenyl tetracosanoate, phenyl pentacosanoate, phenyl hexacosanoate, phenyl heptacosanoate, phenyl octacosanoate, phenyl nonakosanoate, Phenyl triacontanate, phenyl hentriacontanate, phenyl dotriacontanate, phenyltritriacontanate, phenyltetratriacontanate, phenylpentatriacontanate, phenylhexatricontanate, phenylheptatricontanate,
Phenyl nonatriacontanate, phenyltetracontanate, phenylhenetetracontanate, phenyldotetracontanate, phenyltritetraacontanate, phenyltetratetracontanate, phenylpentatetracontanate, phenylhexatetracontanate, heptatetra Phenyl contanate, phenyl octatetracontanate, phenyl nonatetracontanate, phenyl pentacontanate, phenyl hempantacontanate, phenyl dopentacontanate, phenyl tripentacontanate,
Phenyl tetrapentacontanate, phenylpentapentacontanate, phenylhexapentacontanate, phenylheptapentacontanate, phenyloctapentacontanate, phenylnonapentacontanate, phenylhexacontanate, phenyldohexacontanate, phenyldecenoate Phenyl undecenoate, phenyl dodecenoate, phenyl tridecenoate, phenyl tetradecenoate,
Phenyl pentadecenoate, phenyl hexadecenoate, phenyl heptadecenoate, phenyl octadecenoate, phenyl nonadenoate, phenyl eicosenoate, phenyl heneicosenoate, phenyl docosenoate, phenyl trichosenate, phenyl tetracosenoate, phenyl pentacosenoate, phenyl hexacosenoate, heptacosenoate Esters such as phenyl, phenyl octacosenoate and phenyl nonacocene, decyl octacosandioate, undecyl octacosandioate, dodecyl octacosandioate, tridecyl octacosandiodate, tetradecyl octacosandiodate, pentadecyl octacosandiodate, hexadecyl octacosandiodate, and octacosanedioctane. Heptadecyl acid, octadecyl octacosandioate, methyl decandioate, methyl undecandioate, dodecane Methyl acid, tridecanedioic acid methyl,
Methyl tetradecandioate, methyl pentadecandioate, methyl hexadecandioate, methyl heptadecandioate, methyl octadecandioate, methyl nonadecandioate, methyl eicosane diate, methyl heneicosane diate, methyl docosan diate, methyl tricosandioate, Methyl tetracosandioate, methyl pentacosandioate, methyl hexacosandioate, methyl heptacosantioate, methyl octakosantioate, methyl nonacosantioate, methyl triacontanedioate, methyl hentriacontanedioate, methyl dotriacontanedioate, Methyl tritriacontanedioate, methyl tetratriacontanedioate, methyl pentatriacontanedioate, methyl hexatriacontanedioate, methyl heptatriacontanedioate, methyl nonatriacontanedioate,
Methyl tetracontanedioate, methyl hentetracontanedioate, methyl dotetracontanedioate, methyl tritetraacontanedioate, methyl tetratetracontanedioate, methyl pentatetracontanedioate, methyl hexatetracontanedioate, hepta Methyl tetracontanedioate, methyl octatetracontanedioate, methyl nonatetracontanedioate, methyl pentacontanedioate, methyl hempetacontanedioate, methyl dopentacontanedioate, methyl tripentacontanedioate, tetrapentacontan Methyl diacid, methyl pentapentacontanedioate, methyl hexapentacontanedioate, methyl heptapentacontanedioate,
Methyl octapentacontanedioate, methyl nonapentacontanedioate, methyl hexacontanedioate, methyl dohexacontanedioate, methyl decenedioate, methyl undecenedioate, methyl dodecenedioate, methyl tridecenedioate, tetradecenedioate Methyl, methyl pentadecenedioate, methyl hexadecenedioate, methyl heptadecenedioate, methyl octadecenedioate, methyl nonadecenedioate, methyl eicosenedioate, methyl heneicosenedioate, methyl docosenedioate, methyl trichosenedioate, tetracosenedioate Methyl, methyl pentacosenedioate, methyl hexacosenedioate, methyl heptacosenedioate, methyl octacosenedioate, methyl nonakosenedioate, vinyl decane diate, vinyl undecane diate, vinyl dodecane diate, vinyl tridecane diate, tetradecane Vinyl acid, pentadecane diacid vinyl, hexadecane diacid vinyl, heptadecane diacid vinyl, octadecane diacid vinyl, nonadecane diacid vinyl,
Vinyl eicosane diacid, vinyl hen eicosane diacid, vinyl docosane diacid, vinyl tricosandioate, vinyl tetracosane diate, vinyl pentacosane diate, vinyl hexacosane diate, vinyl heptacosane diate, vinyl octacosan diate, vinyl nonacosan diate, Vinyl triacontanedioate, vinyl hentriacontanedioate, vinyl dotriacontanedioate, vinyl tritriacontanedioate, vinyl tetratriacontanedioate, vinyl pentatriacontanedioate, vinyl hexatriacontanedioate, heptatria Vinyl contanedioate, vinyl nonatricontanedioate, vinyl tetracontanedioate, vinyl hentetracontanedioate, vinyl dotetracontanedioate, vinyl tritetraacontanedioate, vinyl tetratetracontanedioate, pentatetraco Tan diacid vinyl, hexamethylene tetra proximal diacid vinyl, hepta tetra proximal diacid vinyl,
Vinyl octatetracontanedioate, vinyl nonatetracontanedioate, vinyl pentacontanedioate, vinyl hempentacontanedioate, vinyl dopentacontanedioate, vinyl tripentacontanedioate, vinyl tetrapentacontanedioate, pentapentacone Vinyl tantalate, vinyl hexapentacontanedioate, vinyl heptapentacontanedioate, vinyl octapentacontanedioate, vinyl nonapentacontanedioate, vinyl hexacontanedioate, vinyl dohexacontanedioate, vinyl decenedioate , Vinyl undecenedioate, vinyl dodecenedioate, vinyl tridecenedioate, vinyl tetradecenedioate, vinyl pentadecenedioate, vinyl hexadecenedioate, vinyl heptadecenedioate, vinyl octadecenedioate, vinyl nonadecenedioate,
Vinyl eicosenedioate, vinyl heneicosenediodate, vinyl docosenedioate, vinyl trichosenedioate, vinyl tetracosenedioate, vinyl pentacosenedioate, vinyl hexacosenediodate, vinyl heptacosenediodate, vinyl octacothenedioate, vinyl nonakosenedioate, Phenyl decandioate, phenyl undecandioate, phenyl dodecandioate,
Phenyl tridecandioate, phenyl tetradecandioate,
Phenyl pentadecandioate, phenyl hexadecandioate, phenyl heptadecandioate, phenyl octadecanedioate, phenyl nonadecanedioate, phenyl eicosanedioate, phenyl heneicosanoedioate, phenyl docosanedioate, phenyl tricosandiodate, phenyl tetracosedionate, Phenyl pentacosantioate, phenyl hexacosantioate, phenyl heptacosantioate, phenyl octakosantioate, phenyl nonakosantioate, phenyl triacontanedioate, phenyl hentriacontanedioate, phenyl dotriacontanedioate, phenyl tritriacontanedioate Phenyl, phenyl tetratriacontanedioate, phenyl pentatriacontanedioate, phenyl hexatriacontanedioate, phenyl heptatriacontanedioate, phenyl nonatriacontanedioate , Tetorakontan diacid phenyl,
Hentetracontanedioic acid phenyl, dotetracontanedioic acid phenyl, tritetraacontanedioic acid phenyl, tetratetracontanedioic acid phenyl, pentatetracontanedioic acid phenyl, hexatetracontanedioic acid phenyl, heptatetracontanedioic acid phenyl, Phenyl octatetracontanedioate, phenyl nonatetracontanedioate, phenylpentacontanedioate, phenyl pentapentacontanedioate, phenyl dopentacontanedioate, phenyl tripentacontanedioate, phenyl tetrapentacontanedioate, pentapentacone Phenyl tannedioate, phenyl hexapentacontanedioate, phenyl heptapentacontanedioate, phenyl octapentacontanedioate, phenyl nonapentacontanedioate, phenyl hexacontanedioate,
Phenyl dohexacontanedioate, phenyl decenedioate,
Phenyl undecenedioate, phenyl dodecenedioate, phenyl tridecenedioate, phenyltetradecenedioate, phenylpentadecenedioate, phenylhexadecenedioate, phenylheptadecenedioate, phenyloctadecenedioate,
Phenyl nonadecenedioate, phenyleicosenedioate, phenylenecosenedioate, phenyl docosenedioate, phenyl trichosenedioate, phenyltetracosenedioate, phenylpentacosenedioate, phenyl hexacosenedioate,
Examples thereof include phenyl heptacosenedioate, phenyl octacosenedioate, and phenyl nonacocenedioate.

The ketones include laurone, stearone, 19-heptatriacontanone, 20-nonatriacontanone, 21-henttetracontanone, 22-
Tritetracontanone and the like can be mentioned.

It is preferred that both esters and ketones have about 10 to 60 carbon atoms. If the number of carbon atoms is less than 10, sufficient white turbidity cannot be obtained, and if the number of carbon atoms is more than 60, it is difficult to obtain.

In actual use of the pressure-sensitive material, a coating solution of the pressure-sensitive material may be adjusted in order to adhere the pressure-sensitive material to a substrate or the like. In this case, it is preferable to obtain a coating solution by dissolving the matrix material and one or more organic low-molecular substances selected from esters and ketones in a solvent. And as this solvent, it is not limited to this, tetrahydrofuran, methyl ethyl ketone,
Methyl isobutyl ketone, chloroform, carbon tetrachloride,
It is preferable to use one selected from ethanol, toluene, benzene, and the like, or to use a mixture of two or more. Further, the coating solution may be heated and used if necessary.

Further, according to the reversible pressure-sensitive recording medium of the second invention of this application, a support and a layer of the pressure-sensitive material of the first invention provided directly or via an intermediate layer on the support. It is characterized by having. Here, the intermediate layer is, for example,
It may be an adhesive layer for enhancing the adhesion between the support and the layer of the pressure-sensitive material, or a reflective layer. In the implementation of the second invention, it is preferable that the support has a configuration in which an enhancement layer and a reflection layer or a light absorption layer are sequentially provided on a surface opposite to a surface on which the pressure-sensitive material layer is provided. It is.
This is because the enhancement layer exists between the support and the reflection layer or the light absorption layer, so that the contrast in display can be improved. In actual use, it is preferable to provide a protective layer on the layer of the pressure-sensitive material. This is because the layer of the pressure-sensitive material can be protected and the durability of the recording medium can be improved. In the above embodiment, in the case where the reflective layer is provided, it is possible to display such that the printed portion is the color of the reflective layer and the background is cloudy, and the contrast is improved. In the case where a light absorbing layer is provided,
A display can be made such that the printed portion is the color of the light absorbing layer and the background is cloudy. In addition, an adhesive layer may be provided between the protective layer, the layer of the pressure-sensitive material, the support, the enhance layer, and the reflective layer (or the absorption layer) as necessary to improve the adhesion strength between the layers. it can.

Here, as a material constituting the support,
Various types according to the design of the recording medium can be used. For example, polyester, polyethylene, polypropylene, cellophane, polyvinyl chloride, polyolefin,
Examples thereof include plastics such as polyvinyl alcohol, polyvinylidene chloride, polystyrene, polyamide, polycarbonate, polyarylate, polysulfone, fluororesin, polyacrylonitrile, polyethersulfan, polybutadiene, and polyimide, paper, and synthetic paper. The thickness of the support may basically be such that the layer of the recording material having reversibility can be maintained. Specifically, it is determined according to the design of the recording medium. For example, if a recording medium in the form of a card is to be formed, the thickness is preferably, for example, 25 μm to 1 mm.

The material constituting the protective layer includes, for example, polyester, polyethylene, polypropylene,
Cellophane, polyvinyl chloride, polyolefin, polyvinyl alcohol, polyvinylidene chloride, polystyrene,
Transparent plastics such as polyamide, polycarbonate, polyarylate, polysulfone, fluororesin, polyacrylonitrile, polyethersulfane, polybutadiene, UV (ultraviolet) curable resin, and inorganic substances such as SiO ₂ and TiO ₂ can be mentioned. . The thickness of the protective layer may be determined in such a range that the purpose as the protective layer can be achieved and the pressure reaches the pressure-sensitive material layer even when using an impact printer head or a stamp. For example, about 1 to 15 μm is desirable.

The materials constituting the enhanced layer include, for example, polyester, polyethylene, polypropylene, cellophane, polyvinyl chloride, polyolefin,
Polyvinyl alcohol, polyvinylidene chloride, polystyrene, polyamide, polycarbonate, polyarylate, polysulfone, fluororesin, polyacrylonitrile, polyethersulfan, polybutadiene, UV
Transparent plastics such as (ultraviolet) curable resins, and transparent inorganic substances such as SiO ₂ can be used.
Further, this enhancement layer may be constituted by an air layer.

Further, as a material constituting the reflection layer or the light absorption layer, a material containing a metal such as aluminum or copper, and / or a pigment or a dye can be used. When a reflective layer or an absorbing layer is formed, it may be performed by a method in which black or red ink is applied onto a support by, for example, a normal film gravure photographer. Depending on the case, a vapor deposition film or the like may be used. The colors of these layers can be arbitrarily determined according to the design of the recording medium. However, basically, a color having a large contrast with the background color of the layer of the pressure-sensitive material is desirable. Further, the reflective layer and the absorbing layer may be formed by printing a plurality of colors having a large contrast with the background color of the layer of the pressure-sensitive material. Further, the reflective layer may be formed by printing a fluorescent paint. Further, the reflection layer and the light absorption layer need not be present in the entire area of the recording medium, and may be present in a part of the medium. Further, the reflection layer and the light absorption layer may be present at different positions on the same medium at the same time.

As the material of the adhesive layer, a mixture of one or more resins such as urethane, epoxy, polyamide, and melamine can be used.

[0024]

The pressure-sensitive material according to the first aspect of the present invention is a material whose transparency changes depending on pressure and temperature, as will be apparent from the experimental results described later. In particular: a material which exhibits a maximum transparency whose transparency has been increased by the application of pressure and which maintains this transparency at room temperature, wherein: a material which is in this certain maximum transparency state is above a certain temperature T ₀ A material which, when heated and then cooled, exhibits a certain minimum transparency (actually a cloudy state) and maintains this minimum transparency at room temperature if no pressure is applied: a material which can reversibly reproduce the above conditions Can be Therefore, an image can be formed by selectively applying pressure to the pressure-sensitive material, and this image can be erased by heating. Therefore, a new material capable of writing and erasing a record using pressure and heat. Is obtained. The temperature T ₀ required to return the pressure-sensitive material to the cloudy state can be changed by a combination of a matrix material and a substance selected from esters and ketones.

Further, according to the reversible pressure-sensitive recording medium of the second invention of this application, it is possible to realize a recording paper, a card or the like utilizing the characteristics of the recording material of the first invention.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the first and second inventions of the present application will be described below. It should be understood that the materials used and numerical conditions described in the following description are merely examples within the scope of the present invention, and therefore the present invention is not limited only to these materials and numerical conditions. I want to. Moreover, the drawings referred to in the description are only schematically shown to the extent that the present invention can be understood.

1. Description of Example of First Invention (Reversible Pressure-Sensitive Material) 1-1. Example 1 As a matrix material, polyvinyl acetal (in this case, SREC KS-1 (trade name) of Sekisui Chemical Co., Ltd.) is prepared. Also, methyl behenate is prepared as an organic low-molecular substance selected from esters and ketones. Methyl behenate is an example of an ester having 23 carbon atoms.

6 parts by weight of Eslek KS-1 and 3 parts by weight of methyl behenate are dissolved in 50 parts by weight of tetrahydrofuran, and a coating solution for preparing a layer of a pressure-sensitive material having reversibility in Example 1 (hereinafter referred to as “coating solution”). Abbreviated as the coating solution of Example 1).

Next, a substrate made of polyethylene terephthalate in this case is prepared as a support. Then, the coating solution of Example 1 is applied on the substrate by a bar coating method, and dried in the air at a temperature of 120 ° C. to form a layer of a reversible pressure-sensitive material. The drying time is set so that the solvent, tetrahydrofuran, can be removed. The sample (layer of the pressure-sensitive material) of Example 1 thus produced exhibited a cloudy color.

Then, a pressure of 10 kg / cm ² was applied to a part of the sample (layer of the pressure-sensitive material) of Example 1 from the surface thereof.
It was found that when the pressure was applied for 2 seconds, the transparency increased only in the pressurized portion, and the substrate became visible, and this state was maintained even when the pressurization was stopped. It was also found that characters could be formed in the pressure-sensitive material layer by setting the pressure region to a region corresponding to, for example, the shape of a character. However, it should be understood that the above pressure application condition is not a critical condition for causing a change in transparency. Critical pressure conditions that cause a change in transparency have not yet been investigated.

Next, this sample was heated in the atmosphere at a temperature of 90 ° C. for 10 seconds and then returned to room temperature. As a result, the sample of Example 1 (pressure-sensitive material layer) was in the state before the above-mentioned pressurization experiment, ie, Then, the whole surface returned to a cloudy state. When the heating condition was set to 80 ° C. for 10 seconds, the sample of Example 1 (pressure-sensitive material layer) was used.
Did not return to a cloudy state. Although the exact value of the critical temperature that causes the change in transparency has not yet been grasped, from the above experimental results, the critical temperature in the case of the sample of Example 1 is in a range of more than 80 ° C and 90 ° C or less. I do. Since the upper limit of the heating temperature is considered to be substantially determined by the softening points of the matrix material and the support, it is considered to be about 200 ° C. in this sample.

When the above-described pressure treatment and heat treatment were performed for many cycles, the sample of Example 1 (the layer of the pressure-sensitive material) was changed in transparency each time as described above. From this, it can be understood that the material of Example 1 is a pressure-sensitive material that exhibits reversibility under pressure and heat.

1-2. Example 2 The reversibility of Example 2 was the same as in Example 1 except that 3 parts by weight of stearone (= diheptadecyl ketone) were used instead of methyl behenate in the composition of the coating solution of Example 1. A coating solution for preparing a layer of a pressure-sensitive material having the following formula is prepared. Note that stearone corresponds to an example of a ketone having 35 carbon atoms.

Next, using this coating solution, a layer of the pressurized material of Example 2 is formed on a substrate made of polyethylene terephthalate by the procedure of Example 1 to obtain an experimental sample.

Next, the characteristics of the change in transparency of the experimental sample with respect to pressure and temperature are examined by the same procedure as in Example 1. As a result, it was found that the reversible transparency change characteristic similar to that of the sample of Example 1 was obtained with the sample of Example 2.

1-3. Example 3 The reversibility of Example 3 was obtained in the same manner as in Example 1 except that 3 parts by weight of 22-tritetracontanone was used instead of methyl behenate in the composition of the coating solution of Example 1. A coating solution for preparing a layer of pressure-sensitive material is prepared. Note that 22-tritetracontanone corresponds to an example of a ketone having 43 carbon atoms.

Next, a layer of the pressurized material of Example 3 is formed on a substrate made of polyethylene terephthalate by the procedure of Example 1 using this coating solution to obtain an experimental sample.

Next, the characteristics of the change in transparency of this experimental sample with respect to pressure and temperature are examined by the same procedure as in Example 1. As a result, it was found that the same reversible transparency change characteristic as that of the sample of Example 1 was obtained with the sample of Example 3.

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1-10. Comparative Examples 1 to 4 (Comparative Example 1) As Comparative Example 1, a reversible thermosensitive recording material will be described. Specifically, the composition having the reversibility of Comparative Example 1 was prepared in the same manner as in Example 1 except that 3 parts by weight of behenic acid was used instead of methyl behenate in the composition of the coating solution of Example 1. A coating solution for preparing a layer of pressure material is prepared.
Next, a layer of the material of Comparative Example 1 is formed on a substrate made of polyethylene terephthalate by the procedure of Example 1 using this coating solution to obtain an experimental sample.

Next, the characteristics of the change in transparency of this experimental sample with respect to pressure and temperature are examined by the same procedure as in Example 1. As a result, when this sample was heated to a temperature of 100 ° C. or more and then rapidly cooled (at a rate of 50 ° C./sec or more), it showed a stable transparent state, and after being heated to a temperature of 85 ° C. or more, gradually cooled (50 ° C. / (A speed slower than 2 seconds), a stable cloudy state was exhibited, but it was found that the transparency did not change by pressurization.

Comparative Example 2 As Comparative Example 2, a pressure-sensitive material using microcapsules will be described. Specifically, crystal violet lactone and benzoyl leuco methylene ble are used as coloring materials, and the microstructure of the CMC wall is determined by a coacervation method using a copolymer of carboxymethylcellulose (hereinafter abbreviated as CMC) and maleic anhydride. A capsule dispersion liquid (a liquid in which microcapsules whose walls are constituted by CMC is dispersed) is prepared (for example, detailed in JP-A-50-140376). next,
Using this microcapsule dispersion, a layer of the material of Comparative Example 2 was formed on a substrate made of polyethylene terephthalate by the procedure of Example 1 to obtain an experimental sample.

The characteristics of the change in transparency of this experimental sample with respect to pressure and temperature are examined by the same procedure as in Example 1. As a result, it was found that this sample can draw characters and the like by pressure, but cannot erase the characters by heat (irreversible pressure-sensitive material).

(Comparative Example 3) A microcapsule dispersion liquid is prepared by using polyacrylic acid instead of CMC in the structure of the microcapsule dispersion liquid of Comparative Example 2. Next, a layer of the material of Comparative Example 3 was formed on a substrate made of polyethylene terephthalate using this microcapsule dispersion liquid in Example 1.
To obtain an experimental sample.

The characteristics of the change in transparency of this experimental sample with respect to pressure and temperature are examined by the same procedure as in Example 1. As a result, it was found that this sample can draw characters and the like by pressure, but cannot erase the characters by heat (irreversible pressure-sensitive material).

(Comparative Example 4) A microcapsule dispersion liquid was prepared by using methyl vinyl ether instead of CMC in the structure of the microcapsule dispersion liquid of Comparative Example 2. Next, a layer of the material of Comparative Example 4 is formed on a substrate made of polyethylene terephthalate by using the microcapsule dispersion liquid according to the procedure of Example 1 to obtain an experimental sample.

The characteristics of the change in transparency of this experimental sample with respect to pressure and temperature are examined by the same procedure as in Example 1. As a result, it was found that this sample can draw characters and the like by pressure, but cannot erase the characters by heat (irreversible pressure-sensitive material).

The pressure-sensitive recording properties and reversibility of the pressure-sensitive materials of Examples 1 to 8 of the first invention and the materials of Comparative Examples 1 to 4 are summarized in Table 1 below.
In Table 1, the symbol “〇” means having the property, and “x” means not having the property.

[0066]

[Table 1]

2. Description of Example of Second Invention (Reversible Pressure-Sensitive Recording Medium) Next, an example of the reversible pressure-sensitive recording medium of the second invention will be described. FIG. 1 is a sectional view for explanation. First, a plastic sheet having a thickness of 100 μm is prepared as the support 11 in this case. The reversible pressure-sensitive recording medium 10 of this embodiment comprises a support 11, a layer 13 of the pressure-sensitive material of the first invention provided on the support 11 and having a thickness of 20 μm in this case; A protective layer 15 provided on layer 13 and having a thickness of 5 μm in this case. Further, in this case, on the surface of the support 11 opposite to the surface on which the pressure-sensitive material layer 13 is provided, an enhance layer 17 and a reflective layer or light absorbing layer 19 having black color are provided in this order. Further, a magnetic recording layer 21 is provided on the reflection layer or the light absorption layer 19.

In the reversible pressure-sensitive recording medium 10 of this embodiment, when pressure is selectively applied to the protective layer 15 from above, the transparency of the layer 13 of the pressure-sensitive material corresponding to that part is increased, and the reflection layer or the light absorbing layer is formed. The corresponding part of the layer 19 becomes visible. Characters and image information can be formed by the contrast between the transparent part and the non-changed part of the pressure-sensitive material layer 13 (the part that remains opaque). In addition, the provision of the enhancement layer 17 separates the pressure-sensitive material layer 13 from the reflection layer or the light absorption layer 19, thereby increasing the contrast. Also,
The image can be erased by heating at least the pressure-sensitive material layer 13 of the reversible pressure-sensitive recording medium 10 of the embodiment to a predetermined temperature and then returning the temperature to room temperature. In simple terms, this can be performed by heating the entire reversible pressure-sensitive recording medium 10 to a predetermined temperature and then returning the medium to room temperature. Here, the predetermined temperature is a temperature within a range in which the transparency of a portion where the transparency is increased by pressurization of the pressure-sensitive material layer 13 returns to the cloudy state before the pressurization. The lower and upper limits may be determined in advance.

Further, in the reversible pressure-sensitive recording material of the second invention, characters and figures can be printed on portions of the protective layer 15 not used for pressure-sensitive recording. As a result, it is possible to record information that needs to be fixed without repeating writing and erasing.

The reversible pressure-sensitive recording medium 1 of this embodiment
Numeral 0 denotes a configuration including the magnetic recording layer 21. Although the magnetic recording layer 21 does not directly relate to the layer 13 of the pressure-sensitive material, a multifunctional information storage medium can be realized in the sense of the reversible pressure-sensitive recording medium 10 capable of magnetic recording. The magnetic recording layer is obtained, for example, by preparing a coating solution containing a magnetic material such as hematite or cobalt ferrite and a binder, coating the coating solution on the back surface of the support, and drying. Alternatively, it can be formed by a method such as bonding a separately prepared film-shaped magnetic recording layer to the back surface of the support. Also,
The magnetic recording layer may be provided on the entire back surface of the support or on a part thereof. Further, the position where the magnetic recording layer is provided is not limited to the back surface of the support, but may be the front surface of the support.

In the embodiment of the second invention, the reversible pressure-sensitive recording medium is constituted by a laminate comprising a support, a reflective layer (light absorbing layer), an enhance layer, a layer of a pressure-sensitive material, and a protective layer. The configuration is not limited to this, and can be changed according to the design.

[0072]

As is clear from the above description, according to the first invention of this application, an image can be formed by selectively applying a pressure, and this image can be erased by heating. A new pressure-sensitive material having Further, the medium according to the second invention, in which the support is provided with the layer of the pressure-sensitive material of the first invention, can form an image by selectively applying pressure and can erase this image by heating. It is a new recording medium having reversibility. Therefore, according to the first and second inventions, specific effects as described below can be obtained. (1) A recording medium that can be used instead of paper in a handwritten recording method is obtained. (2) Information can be freely printed and recorded by a simple pressure means such as an impact printer. Therefore, printing can be performed by using a known impact printer using the ink ribbon without using the ink ribbon. (3) Since information can be recorded / erased, it can be used repeatedly as many times as possible, which is excellent in resource saving. (4) To erase recorded information, a temperature higher than a room temperature (that is, a temperature higher than a critical temperature (in a range of more than 80 ° C. and 90 ° C. or less)), and the upper limit of the heating temperature is 200
° C), the recorded information is stably maintained at about room temperature. (5) Since the color of the support and the like can be arbitrarily devised, a recording medium with high contrast can be obtained. (6) Since a card-shaped recording medium can be configured, a recording medium having excellent portability can be obtained. For example, it can be used for a prepaid card or a display label. (7) A recording medium that can be used as a sheet for an OHP (overhead projector) and that can be written at any time during use can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining an example of a reversible pressure-sensitive recording medium according to a second invention.

[Explanation of symbols]

 10: Reversible pressure-sensitive recording medium of Examples 11: Support 13: Layer of pressure-sensitive material of the first invention 15: Protective layer 17: Enhanced layer 19: Reflective layer or light absorbing layer 21: Magnetic recording layer

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takeyuki Sekiya 1-7-12 Toranomon, Minato-ku, Tokyo Oki Electric Industry Co., Ltd. (72) Inventor Yukihisa Okada 1-7-1 Toranomon, Minato-ku, Tokyo No. Oki Electric Industry Co., Ltd. (56) References JP-A-63-256481 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/00 B41M 5/124 B41M 5 / 36

Claims (4)

(57) [Claims] 1. A matrix material comprising polyvinyl acetal as a main material, and one or more organic low-molecular substances selected from esters and ketones mixed with the matrix material, wherein the matrix material and the organic material A pressure-sensitive material having reversibility, wherein a mixing ratio (weight ratio) with a low-molecular substance is in the range of 1: 2 to 20: 1. 2. The reversible pressure-sensitive material according to claim 1, wherein the matrix material comprises only polyvinyl acetal. 3. A reversible pressure-sensitive recording comprising a support and a layer of the pressure-sensitive material according to claim 1 provided directly or via an intermediate layer on the support. Medium. 4. The reversible pressure-sensitive recording medium according to claim 3, wherein an enhancement layer and a reflection layer or a light absorption layer are sequentially provided on a surface of the support opposite to a surface on which the layer of the pressure-sensitive material is provided. A reversible pressure-sensitive recording medium characterized by comprising: