JPH0126351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat-sensitive recording material on which information can be reversibly recorded and erased by heating.

Conventionally, spiropyran compounds and metal complex crystals are known as substances that change color and fade depending on temperature, and are used in thermometers and the like. However, this substance repeatedly develops and discolors reversibly with changes in temperature, has no memory properties, and is used in temperature display materials and the like.

On the other hand, in recent years, thermosensitive members have been discovered that can reversibly repeat a cloudy state and a transparent state due to temperature changes, and can stably maintain either state below a certain temperature. The heat-sensitive body is composed of a matrix material made of a polymer or the like and an organic low-molecular substance dispersed in the matrix material, and the properties of the heat-sensitive body are mainly based on the behavior of the organic low-molecular substance. The thermosensitive body has two state transition temperatures, and when it is heated and held at a certain temperature and then cooled down to a specific temperature or lower, it becomes cloudy or transparent depending on the difference in heating and holding temperature. Heat-sensitive recording materials have been proposed that utilize these properties to freely record and erase information.

Recording of information on the recording material is mainly performed by lens condensed heat, light irradiation heat, Joule heat, etc.; however, heat sources emitted by optical means such as lens condensed heat, light irradiation heat, etc. This is an excellent method in that it increases the durability of the recording material because the recording device does not come into direct contact with the surface of the recording material. However, when recording image information on the recording material using an optical heat source, there is a drawback that when irradiated with light, the surface reflectance of the light is large and the light does not enter efficiently, and in addition, a large amount of transmitted light generates heat. It has the disadvantage of low efficiency.

The object of the present invention is to solve the above-mentioned drawbacks all at once, and to provide a heat-sensitive recording material in which information can be reversibly recorded and erased by temperature, and image information can be efficiently recorded by light. Our goal is to provide the following.

The heat-sensitive recording material of the present invention comprises: a matrix material comprising at least one polymer selected from polyvinyl chloride, vinyl chloride copolymer, vinylidene chloride copolymer, and polyester; number of carbons
Light is reflected on a light-absorbing thermosensitive material consisting of at least one organic low-molecular substance selected from esters, amides, and ammonia salts of 10 to 30 saturated or unsaturated fatty acids, and a light-absorbing agent selected from dyes or pigments. It is provided with a prevention layer.

In the present invention, the matrix material, which is a constituent material of the thermosensitive member, is a material for forming a film in which an organic low-molecular substance and a light absorbing agent are uniformly dispersed, and the organic low-molecular substance is held in the matrix material. This has the effect of more clearly expressing the change in state between cloudy and transparent in a particulate organic low-molecular substance. Therefore, this matrix material
Polymers that have good transparency, are mechanically stable, and can be easily formed into a film are preferred.

Examples of such matrix materials include polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, and vinyl chloride-acrylate copolymer. One or more polymers selected from vinyl chloride copolymers such as polymers, vinylidene chloride copolymers such as vinylidene chloride-vinyl chloride copolymers, vinylidene chloride-acrylonitrile copolymers, and polyesters. It can be used.

In the present invention, the organic low-molecular substance that is the constituent material of the thermosensitive member changes its refractive index as its state changes due to heating, and at the same time, its state is maintained through interaction with the matrix material. , for example, from saturated or unsaturated fatty acids having 10 to 30 carbon atoms, such as palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, linoleic acid, linolenic acid, etc., or esters, amides and ammonium salts of said fatty acids. One or more selected compounds can be used.

There is a preferable combination of the matrix material and the organic low-molecular substance, which is appropriately determined based on the refractive index of the matrix material and the refractive index of the organic low-molecular substance so as to clearly show the heat sensitive body and the cloudy state and transparent state. .

The following alkanols; alkanediols; halogen alkanols or halogen alkanediols; alkylamines; alkanes; alkenes; alkynes; halogen alkanes; halogen alkenes; halogen alkynes; Alkanes;
cycloalkenes; cycloalkynes; saturated or unsaturated halogenated fatty acids or their esters, amides, or ammonium salts; arylcarboxylic acids or their esters, amides, or ammonium salts; halogenarylcarboxylic acids or their esters, amides, or ammonium salts ;
Examples include organic low-molecular substances such as thioalcohol; thiocarboxylic acid or its ester, amine, or ammonium salt; carboxylic acid ester of thioalcohol, and mixtures thereof. The carbon number of these compounds is 10 to 60, preferably 10 to 38,
Particularly preferred is 10-30. The alcohol moiety in the ester is saturated or unsaturated, and may be further substituted with halogen. The halogen atom is chlorine or bromine, with chlorine being particularly preferred. Preferably, the halogen compound has 1 to 20 halogen substituents. The aryl group is preferably phenyl or substituted phenyl.

In addition, in this specification, organic low molecular substances are 100 to
700 preferably an organic compound with a molecular weight of 300-500. and the organic low molecular weight substance has a phase change of at least 5%, preferably 5% when it undergoes a phase change from solid to liquid.
It is preferable to use one whose volume changes by ~15%.

The light absorber in the present invention is a dye or pigment that efficiently absorbs light and generates heat, and is appropriately selected depending on the wavelength of the irradiated light. For example, absorbers for a green Ar laser beam with a wavelength of 488 nm include dyes that selectively absorb green light;
For example, red dyes or pigments are used,
Examples include Easton Red R, Easton Red B, ethyl Red, 1-(2-pyridylazo)-2-naphthol, and the like. As an absorber for the red He-Ne laser beam with a wavelength of 632.8 nm,
A dye that selectively absorbs red light, such as a blue or green dye or pigment, is used, such as methylene blue, Priliant green, etc. As an absorber for near-infrared semiconductor laser beams with a wavelength of 800 to 1700 nm (e.g., GaAlAs, etc.), dyes that absorb near-infrared light with high optical efficiency, such as black dyes or pigments, are used, such as nigrosine, Examples include cyanine dyes and carbon black.

The antireflection layer in the present invention has the function of preventing light from being reflected on the surface of the thermosensitive member and allowing the light to be efficiently absorbed. The anti-reflection layer contains Pb,
Metal oxides such as W, Ti, Si, Zr, Ge, In,
Inorganic compounds that can be vapor deposited are preferred, such as metal alkogenides such as Sn, Cu, Ag, Fe, Bi, and Al, and metal halides such as Ag and Sb. in particular
Oxides such as PbO, WO ₃ , TiO ₂ , SiO, SiO ₂ , ZrO ₂ , GeO _{2 , GeS 2 ,} In ₂ O ₃ , In ₂ S ₃ , In ₂ Se ₃ ,
Examples include chalcogen compounds such as CuO, CuO ₂ , Ag ₂ O, and Ag ₂ S, and halogen compounds such as AgX and SbX ₅ (X is F, Cl, Br, and I).

Hereinafter, one embodiment of the recording material of the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows a cross-sectional view of a heat-sensitive recording material that is an embodiment of the present invention, and the method for manufacturing the material will be described below, as well as its structure will be explained in detail.

As shown in FIG. 1, this heat-sensitive recording material has a heat-sensitive member 2 and a light reflection prevention layer 3 provided on a base material 1 in this order.

The heat sensitive member 2 is made by uniformly mixing the matrix material, organic low molecular weight substance and light absorbing agent, and applying the mixture to a film of 5 to 100 μm, preferably 10 to 50 μm, using a casting method or the like to form a film of plastic, glass, etc. It is formed by laminating it on the base material 1.

Next, the above-mentioned vapor-depositable inorganic compound is laminated on the heat sensitive member 2 to a thickness of 5 to 100 nm by sputtering or vacuum vapor deposition to form the antireflection layer 3.

In the mixture, the mixing ratio of the matrix material and the organic low-molecular substance is 1:1/by weight.
The ratio is 16 to 1:1/3. The mixing ratio of the light absorber to the matrix material varies depending on the type of light or whether a dye or a pigment is used, and is determined appropriately depending on each case.

As other methods for forming the film-like heat sensitive body 2, a wide variety of known molding methods for polymers used as matrix materials can be used. Furthermore, in order to impart appropriate physical properties to the heat-sensitive body and to improve processability, plasticizers, lubricants, stabilizers, etc. can be added to the heat-sensitive body as necessary.

The base material 1 is made of paper, in addition to plastic and glass.
Cloth, metal, etc. can also be used, but it is preferable to use a material that allows the change in cloudiness of the heat-sensitive member to be clearly seen, and usually transparent plastic or glass is used.

In addition, as shown in Figure 2, by using a large amount of matrix material and organic low-molecular substances,
If the heat-sensitive body 2 is formed thickly and the heat-sensitive body itself can sufficiently maintain its solid shape, it is also possible to construct a heat-sensitive recording material without using a base material.

In another aspect of the heat-sensitive recording material of the present invention, the third
As shown in the figure, a light absorption layer 4 with a thickness of 1 to 10 μm is provided on a base material 1, and then a thin film 5 made of a matrix material and an organic low-molecular substance is provided on the light absorption layer 4 and the thin film 5. A heat sensitive body 2' consisting of two layers is formed, and an antireflection layer 3 is further formed thereon.

The light-absorbing layer 4 is formed by applying a mixture of a polymer having suitable film-forming properties and a light-absorbing agent uniformly mixed in a solvent onto the base material 1 .

The polymer is preferably a polymer that can be easily formed into a film, and includes the polymer used for the matrix material and other known polymers such as cellulose resin, acrylic resin, polystyrene, and polyamide resin.

Hereinafter, a temperature-dependent reversible image information recording and erasing mechanism of the heat-sensitive recording material of the present invention and an image information recording method will be explained.

The heat sensitive bodies 2, 2' of the heat sensitive recording material of the present invention are:
When maintained at a specific temperature t ₀ or higher, the state changes depending on the temperature. By the way, the dye or pigment in the heat sensitive body 2 and the light absorption layer 4 in the heat sensitive body 2' are not directly involved in the above-mentioned properties. Let us explain the change in state assuming that

That is, the heat sensitive body of the heat sensitive recording material of the present invention has two state transition temperatures t ₁ and t ₂ at a temperature higher than t ₀ .
(t ₁ < t ₂ ), and after heating and holding above t ₂
When cooled to below t ₀ , it becomes cloudy and reaches maximum light shielding. On the other hand, when this cloudy heat sensitive body is heated and held at a temperature range of t ₀ or more and less than t ₁ and then cooled to t ₀ or less,
The heat sensitive element becomes transparent. In addition, when the cloudy heat sensitive body is heated and held at a temperature range of t ₀ or more and less than t ₁ and then cooled to t ₀ or less, the heating holding temperature is from t 0 to t ₀ or less.
As the temperature increases to t ₁ , the white turbidity of the thermosensitive member when cooled shows a continuous intermediate white turbidity ranging from the white turbidity of the maximum light shielding state to the transparent state.

Therefore, the actual state change of the heat sensitive body 2 in which the color tone of the dye or pigment is synthesized with the state change of the heat sensitive body 2 is a colored opaque state when the heat sensitive body is cloudy, and a colored opaque state when the heat sensitive body is transparent. In the case of , it indicates a colored transparent state.

On the other hand, the actual state change of the heat sensitive element 2' formed by laminating the thin film 5 made of a matrix material and an organic low-molecular substance on the light absorption layer 4 is that the thin film 5 exhibits the above-mentioned state change. When the thin film 5 is in a cloudy state, it indicates a cloudy state, and when the thin film 5 is in a transparent state, it indicates a colored and transparent color tone of the light absorption layer 4 as the lower layer.

Therefore, image information is recorded on the heat sensitive bodies 2, 2' by being selectively heated, and is erased when unnecessary, so that the heat sensitive bodies 2, 2' are used as recording materials. In the heat-sensitive recording material of the present invention using the heat-sensitive members 2 and 2', image information is recorded using various heat sources such as lens condensed heat, light irradiation heat, and Joule heat. A light absorber is added that efficiently absorbs light of that wavelength, and an anti-reflection layer is also provided, making it possible to efficiently record information using light. be. As the light, a laser beam is most preferable because it has characteristics such as high brightness, excellent monochromaticity, sharp directivity, and high convergence.

Next, a method for recording image information using a laser beam as an example of a heating recording source will be described.

For example, when using a green Ar laser beam with an oscillation wavelength of 488 nm as a recording heat source,
A heat-sensitive recording material is prepared in which a red dye or pigment is added as a light absorber into a heat-sensitive member 2. The recording material is heated to a temperature of t ₂ or higher, and then cooled to a temperature of t ₀ or lower to make the entire surface of the heat sensitive body 2 of the recording material red and opaque. The recording material is selectively heated and held at a temperature of t ₁ or more and less than t ₂ . At this time, the portion of the recording material that is irradiated with the laser beam is protected by the anti-reflection layer 3, which suppresses the reflected laser beam on the surface of the recording material. It efficiently absorbs irradiated light, generates heat, and easily reaches the desired temperature.
When the recording material is then cooled to below t ₀ , the heated portion of the recording material becomes red and transparent, and red and transparent image information is recorded on the recording material that has an opaque red background.

Further, the heat-sensitive recording material of the present invention is heated and maintained at a temperature of t ₁ or more and less than t ₂ , and then cooled to t ₀ or less to make the entire surface of the heat-sensitive body 2 of the recording material red and transparent, and then the recording material is coated with the above-mentioned A laser beam is irradiated to selectively heat and maintain the recording material to t2 _or higher depending on the image information. At this time as well, the recording material easily attains the desired temperature for the same reason as described above. Then the recording material
When cooled below t ₀ , the heated part of the recording material becomes red and opaque, and the red transparent recording material becomes
Red opaque image information is recorded.

On the other hand, in a heat-sensitive recording material using a heat-sensitive body 2' consisting of two layers: a light-absorbing layer 4 and a thin film 5 made of a matrix material and an organic low-molecular substance, the thin film 5 made of a matrix material and an organic low-molecular substance is In the completely transparent state, when this recording material is viewed from above, the underlying red light absorption layer 4 can be seen through. When the recording material in this state is selectively irradiated with a laser beam in accordance with the image information, the laser beam that passes through the transparent thin film 5 hits the light absorbent layer 4 and causes that part to generate heat. The heat is conducted to the thin film 5 above, and the thin film 5 is heated to more than _t2 , and image information is recorded as cloudy. Therefore, when the recording material is visually observed from above, cloudy image information is observed recorded on the red base of the light absorbent layer.

On the other hand, when the thin film 5 made of the matrix material and the organic low-molecular substance is completely cloudy, the underlying red light-absorbing layer 4 is shielded from light. Even when irradiated with a laser beam, the effect of the light absorbent layer 4 is weak, but if the thin film 5 is thin enough that the light absorbent layer 4 can be seen through, the thin film 5 is transparent. As in the above case, the effect of the light absorbent layer 4 is sufficiently exhibited, and the irradiated portion of the thin film 5 is efficiently heated. Furthermore, if the base material 1 is transparent regardless of the thickness of the thin film 5, by irradiating the laser beam from the back surface of the base material to selectively heat the light absorbent layer 4, the conductive heat can be absorbed. Therefore, it is possible to change the thin film 5 to be transparent.

Hereinafter, examples and comparative examples of the heat-sensitive recording material of the present invention will be described in more detail.

Example 1 A mixture consisting of 1.5 g of Saran resin R-200 (trade name, manufactured by Asahi Dow Co., Ltd., vinylidene chloride-acrylonitrile copolymer), 0.250 g of behenic acid, and 0.015 g of Priliant Green was sufficiently dissolved in 8 g of tetrahydrofuran, and then a Mylar film was prepared. (polyester film) with a 4mm blade, then
After drying at 80° C. for 10 minutes, it was rapidly cooled to form a heat sensitive member with a film thickness of 10 μm. Then add RF spats on top of this.
WO ₃ was deposited to form an antireflection layer with a thickness of 0.05 μm. The heat sensitive body constituting the heat sensitive recording material thus prepared was in a green opaque state.

When the recording material was irradiated with a laser beam for 0.01 m sec using a He-Ne laser oscillator with an output of 6 mW (oscillation wavelength: 632.8 nm, beam diameter: 2 μm),
The irradiated area of the recording material turned green and transparent. The recording material was further heated and held at 80° C. and then rapidly cooled, and the entire surface became green and opaque again.

Example 2 After thoroughly dissolving a mixture consisting of 0.1 g of Easton Red R (manufactured by Eastman Kodak Co., Ltd.) and 1 g of cellulose acetate butyrate in 10 g of cyclohexanone, this solution was applied onto Mylar film (polyester film) with a 2 mm blade. Then, it was dried at 50° C. for 10 minutes to form a light absorption layer with a thickness of 3 μm.

Next, a solution of a mixture of 1.5 g of Saran resin R-200 (manufactured by Asahi Dow Co., Ltd., vinylidene chloride-acrylonitrile copolymer) and 0.250 g of behenic acid sufficiently dissolved in 8 g of tetrahydrofuran was applied onto the light-absorbing layer using a 4 mm blade. , dried at 80℃ for 10 minutes, then rapidly cooled to determine the film thickness.
A 10 μm thin film was formed. Next, TiO ₂ was vapor-deposited thereon by RF sputtering to form an antireflection layer with a thickness of 0.05 μm. The thin film made of Saran resin and behenic acid that makes up the heat-sensitive recording material created in this way is
Since it was as thin as 10 μm, the underlying light-absorbing layer could be seen through, giving it a pale red opaque color.

When the recording material was irradiated with a laser beam for 1 μsec using an Ar laser oscillator with a maximum output of 1 W (oscillation wavelength: 488 nm, beam diameter: 10 μm), the irradiated area became transparent and the underlying red light absorption layer was exposed.
When the recording material was further heated and maintained at 80° C. and then rapidly cooled, the entire surface became pale red and opaque again.

Comparative Example A heat sensitive body was formed on a Mylar film using the same formulation and method as in Example 1, and a recording material was used as it was without providing an antireflection layer. Next, the same operation as in Example 1 was performed using the same laser beam and under the same conditions.
The part of the recording material that is irradiated with the laser beam is
Although the turbidity was lighter compared to the green opaque base part,
It was not completely transparent.

As described above, the heat-sensitive recording material of the present invention allows information to be reversibly recorded and erased by heating.
This heat-sensitive recording material efficiently absorbs irradiation light such as a laser beam and generates heat through the light absorber and antireflection layer, so when a beam-shaped light beam, especially a laser beam, is used as a heating means, Information can be recorded efficiently.

[Brief explanation of drawings]

1 to 3 are cross-sectional views of examples of the heat-sensitive recording material of the present invention. DESCRIPTION OF SYMBOLS 1... Base material, 2, 2'... Heat sensitive body, 3... Light antireflection layer, 4... Light absorption layer, 5... Thin film consisting of a matrix material and an organic low molecular substance.

Claims (1)

[Scope of Claims] 1. A matrix material made of at least one kind of polymer selected from polyvinyl chloride, a vinyl chloride copolymer, a vinylidene chloride copolymer, and a polyester. 2. Carbon dispersed in the matrix material. number
A light-absorbing thermosensitive material comprising at least one organic low-molecular substance selected from 10 to 30 saturated or unsaturated fatty acids, esters, amides, and ammonia salts of the fatty acids, and 3. A light absorbent selected from dyes or pigments. A heat-sensitive recording material with an anti-reflection layer on top.