JP2000006522A - Thermal recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable recording indication by laser of low output as for as possible by adding a conductive polymer in a layer on the uppermost of a thermal recording layer. SOLUTION: The thermal recording medium 1a is formed such that an aluminum-vaporized layer 3 is formed on the upper part of a base material 2 consisting of polyethylene terephthalate(PET), and application liquid A consisting of PMMA resin M 1002B or the like is coated on the aluminum- evaporized layer 3 so as to be 10 μm in its dry film thickness by means of a bar coater before forming a liquid crystal-dispersed film 4. Next, coating liquid B consisting of polyester emulsion ES-850 or the like is coated on the upper layer of the liquid crystal-dispersed film 4 by means of a bar coater to be 3 μm in its dry film thickness before forming a conductive layer 5. Thereafter, printing is carried out on the thermal recording medium 1a with an energy of 30 mJ/mm2 in 1 milli-second by the semiconductor infrared laser of a wavelength of 985 nm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosensitive recording medium having an irreversible thermosensitive recording layer or a reversible thermosensitive recording layer, and more particularly, to recording on a thermosensitive recording layer.
The present invention relates to a thermal recording medium having a thermal recording layer suitable for laser recording.

[0002]

2. Description of the Related Art Conventionally, a thermosensitive recording medium performs recording and display by closely contacting a thermal head over an upper portion of a thermosensitive recording layer and transmitting heat energy directly or through a protective layer formed on the uppermost portion of the thermosensitive recording layer. In addition, when the thermal head is brought into close contact with the thermal head, there is a problem that the thermal head is scummed and the thermal head is worn. Also, particularly in the case of a reversible thermosensitive recording layer, even if a protective layer is provided, the protective layer is physically damaged by the pressure of the thermal head, so that traces of previous print information remain on the protective layer. There were also problems.

[0003] In order to solve the problem of printing on the heat-sensitive recording layer by the thermal head, recording and display by a laser have been studied. However, the heat-sensitive coloring layer generally does not absorb light in the visible and near-infrared regions. It is inefficient and the power of the laser must be increased. Therefore, there is a problem that the device becomes large-scale.
In order to solve the above problem, a light-absorbing substance suitable for the laser wavelength has been added to the heat-sensitive recording layer, but most of inorganic and organic compounds having absorption in the near infrared are colored. However, there is a problem that whiteness is reduced and design restrictions are imposed. Moreover, most transparent organic compounds having absorption in the near infrared have no conductivity and do not have an antistatic effect.

[0004]

SUMMARY OF THE INVENTION The present invention provides a conductive thermosensitive recording medium having a thermosensitive recording layer capable of recording and displaying by using a laser in order to prevent the above-mentioned problems. The purpose is to do so. In particular, an object of the present invention is to provide a thermosensitive recording medium having a thermosensitive recording layer capable of recording and displaying by using a laser with a power as low as possible. Another object of the present invention is to provide a thermosensitive recording medium having an excellent antistatic effect.

[0005]

Means for Solving the Problems In order to achieve the above object, a thermosensitive recording medium according to the present invention comprises a thermosensitive recording medium having a thermosensitive recording layer formed on a base material. It is characterized in that the layer contains a conductive polymer.

[0006] Further, according to the heat-sensitive recording medium of the present invention, in a heat-sensitive recording medium having a heat-sensitive recording layer formed on a substrate, a layer containing a conductive polymer is formed on the heat-sensitive recording layer. It is characterized by becoming.

[0007] The conductive polymer has a formula in the presence of a polyanion.

Embedded image In the formula, R ₁ and R ₂ are independently hydrogen or C ₁ ~ ₄ alkyl group, or the corresponding structural units to form a since it optionally an optionally substituted C ₁ ~ ₄ alkylene group with The thermosensitive recording medium is a dispersion of polythiophene comprising:

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the invention of the thermosensitive recording medium of the present invention will be described in detail. According to the present invention, a layer containing a polythiophene having the structural formula described in JP-A-7-90060 is provided on the uppermost layer of the heat-sensitive recording layer or on the layer formed on the heat-sensitive recording layer. The conductive polymer containing a polythiophene having the structural formula described in JP-A-7-90060 is commercially available from Bayer AG in Germany under the trade name of the conductive polymer “Baytron”. (Hereinafter referred to as JP-A-7-900
The conductive polymer containing a polythiophene having the structural formula of No. 60 is referred to as Baytron or Bytron. The polythiophene having the structural formula described in the above-mentioned JP-A-7-90060 is as follows.

Formula in the presence of a polyanion

[0010]

Embedded image

[0011] formula, R ₁ and R ₂ represent independently hydrogen or C ₁ ~ ₄ alkyl group, or since it optionally an optionally substituted C ₁ ~ ₄ alkylene group together, preferably optionally alkyl optionally substituted methylene group, optionally C ₁ ~ ₁₂ - alkyl or phenyl optionally substituted 1,2-ethylene group, a 1,3-propylene group or a 1,2-cyclohexylene group, the corresponding The present invention relates to a dispersion of polythiophene composed of the following structural units.

All methyl and ethyl groups are R ₁ and R ₂
Mentioned above as C ₁ ~ ₄ alkyl groups relative.

R ₁ and R ₂ may form together,
The preferred representatives of the optionally optionally substituted C ₁ to ₄ alkylene group α- olefins such as ethene, prop-1
Ene, hex-1-ene, oct-1-ene, des-1
-1,2-alkylene groups derived from 1,2-dibromoalkanes obtained by bromination of -ene, dodes-1-ene and styrene. Other representatives include 1,2-cyclohexyl, 2,3-butylene, 2,3-dimethyl-
There are 2,3-butylene and 2,3-pentylene groups.

Preferred R ₁ and R ₂ are methylene, 1,2-
These are ethylene and 1,3-propylene groups, with 1,2-ethylene being particularly preferred.

The polyanions are polymeric carboxylic acids such as polyacrylic acid, polymethacrylic acid or polymalenic acid, and polymeric sulfonic acids such as polystyrene sulfonic acid and polyvinyl sulfonic acid. Also, these polycarboxylic acids and polysulfonic acids can be copolymers of vinylcarboxylic acid and vinylsulfonic acid with other polymerizable monomers such as acrylates and styrene.

The molecular weight of the polyacid which supplies the polyanion is preferably in the range from 1,000 to 2,000,000, more preferably in the range from 2,000 to 500,000.

Next, the thermosensitive recording layer includes an irreversible thermosensitive recording layer and a reversible thermosensitive recording layer. The irreversible thermosensitive recording layer includes a layer mainly composed of an electron-donating usually colorless or light-colored dye precursor and an electron-accepting developer, or a layer which destroys a metal film by heat. In addition, the reversible thermosensitive recording layer can be repeatedly changed between a cloudy state and a transparent state reversibly by a difference in heating temperature,
By utilizing a physical change such that any state is stably maintained at a specific temperature or less, or usually by heating a colorless or pale color dye precursor and heating and subsequent cooling, the dye precursor And a reversible color developer which causes a reversible color tone change.
Furthermore, in the sense of thermal recording, optical disks,
An optical recording medium such as an optical card and a liquid crystal display medium using a nematic liquid crystal, a smectic liquid crystal, a cholesteric liquid crystal or the like are also conceivable.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. However, the present invention is not limited to these drawings and examples. FIG. 1 is a sectional view of a first embodiment of a thermal recording medium of the present invention, FIG. 2 is a sectional view of a second embodiment of the thermal recording medium of the present invention, and FIG. 3 is a sectional view of a third embodiment of the thermal recording medium of the present invention. FIG. 4 is a sectional view of Example 4 of the thermal recording medium of the present invention.

Hereinafter, a specific embodiment will be described. [Embodiment 1] FIG. 1 is a sectional view of Embodiment 1 of a thermosensitive recording medium of the present invention using a thermosensitive recording layer of a liquid crystal dispersion system. The heat-sensitive recording medium 1a of Example 1 has an aluminum vapor-deposited layer 3 on a base material 2 made of polyethylene terephthalate (PET).
Was formed, and the following coating liquid A was applied on the aluminum vapor-deposited layer 3 by a bar coater so that the dry film thickness became 10 μm, and a liquid crystal dispersion film 4 was formed. (Composition of the coating liquid A) Smetic liquid crystal M90054 (SN transition point 95 degrees) (manufactured by Japan Energy Co., Ltd.) 4 parts by weight PMMA resin M1002B (Tg 105 ° C., molecular weight 500,000 to 600,000) (manufactured by Soken Chemical Company) 60 parts by weight 2 colors Pigment G206 (manufactured by Nippon Kogaku Dyeing Co., Ltd.) 0.03 parts by weight Two-color dye G472 (manufactured by Nippon Koso Sekiyu Co., Ltd.) 0.03 part by weight Was stirred and mixed to obtain a coating solution A.

Next, the following coating solution B was applied to the upper layer of the liquid crystal dispersion film 4 with a bar coater so as to have a dry film thickness of 3 μm to form a conductive layer 5. (Composition of the coating liquid B) Polyester emulsion ES-850 (manufactured by Dainippon Ink and Chemicals, Inc.) 1.67 parts by weight Solvent (water / IPA = 75/25) 0.63 parts by weight Baytron (Bytron P, manufactured by Bayer) 7.7 parts by weight A mixture obtained by stirring and mixing all of the above was used as a coating liquid B.

Then, the heat-sensitive recording medium 1 of the first embodiment
On a, a semiconductor infrared laser (GaAs junction laser) having a wavelength of 985 nm was printed with an energy of 30 mJ / mm ² per millisecond.

Example 2 FIG. 2 is a sectional view of Example 2 of a thermosensitive recording medium of the present invention using a leuco-based thermosensitive recording layer. The thermosensitive recording medium 1b of Example 2 has a thickness of 188 μm made of white polyethylene terephthalate (PET).
On the upper part of the base material 6 m, the following coating liquids A and B were mixed at a weight ratio of 1:
Then, the mixture was stirred so as to have a thickness of 2 and then coated with a bar coater so as to have a dry film thickness of 6 μm to form a heat-sensitive recording layer 7. (Composition of coating liquid A) Leuco dye (crystal violet lactone) 10 parts by weight 10% aqueous solution of polyvinyl alcohol 15 parts by weight Water 20 parts by weight (Composition of coating liquid B) Developer 2,2-bis (4-hydroxyphenyl) -N-heptane 10 parts by weight polyvinyl alcohol 10 parts by weight water 20 parts by weight

A conductive layer 8 was formed by coating 3 μm of Baytron (manufactured by Bayer) on the heat-sensitive recording layer 7. Then, printing was performed on the thermosensitive recording medium 1b of Example 2 with the same semiconductor infrared laser (GaAs junction laser) having a wavelength of 985 nm as in Example 1 at an energy of 25 mJ / mm ² for 1 millisecond.

Example 3 FIG. 3 is a cross-sectional view of Example 3 of a thermosensitive recording medium of the present invention using a reversible thermosensitive recording layer of a fatty acid type. The thermosensitive recording medium 1c of Example 3 has a thickness of 1 made of transparent polyethylene terephthalate (PET).
An aluminum vapor-deposited layer 10 having a thickness of 600 ° is formed on the base material 9 having a thickness of 88 μm. The aluminum vapor-deposited layer 10 is coated on the aluminum vapor-deposited layer 10 with the following coating liquid so that the dry film thickness becomes 10 μm. The recording layer 11 was formed. (Coating liquid for reversible thermosensitive recording layer) Hebenic acid 7 parts by weight Sebacic acid 3 parts by weight Vinyl chloride-vinyl acetate copolymer (manufactured by VYHH UCC) 20 parts by weight Tetrahydrofuran 50 parts by weight Ethyl cellosolve 50 parts by weight

A conductive layer 12 was formed by coating 3 μm of Baytron (manufactured by Bayer) on the heat-sensitive recording layer 11. Then, printing was performed on the thermosensitive recording medium 1c of Example 3 with the same semiconductor infrared laser (GaAs junction laser) having a wavelength of 985 nm as in Example 1 at an energy of 30 mJ / mm ² for 1 millisecond.

Example 4 FIG. 4 is a cross-sectional view of Example 4 of a heat-sensitive recording medium of the present invention using a heat-sensitive destruction type heat-sensitive recording layer. The thermosensitive recording medium 1d of Example 4 has a thickness of 188 made of white polyethylene terephthalate (PET).
a 2 to 3 μm thick black colored layer 14 of carbon black-containing polyester resin
A 2 μm-thick vapor deposition anchor layer 15 made of a vinyl chloride-vinyl acetate copolymer is laminated on the coloring layer 14, and a 800 ° -thick tin vapor deposition layer 16 is formed on the vapor deposition anchor layer 15. The layers are laminated, and the upper layer is Baytron (By)
(tron P, manufactured by Bayer AG) 3 μm.
The conductive layer 17 was formed. Then, a semiconductor infrared laser (GaAs junction laser) having the same wavelength of 985 nm as in Example 1 was applied to the thermosensitive recording medium 1d of Example 4 for 5 milliseconds per millisecond.
Printing was performed with an energy of 0 mJ / mm ² .

Next, in order to compare the printing state of a thermosensitive recording medium using Baytron (manufactured by Bayer) and a thermosensitive recording medium not using Baytron,
With the same configuration as in the above-described embodiments 1 to 4,
ron P (manufactured by Bayer AG) were manufactured as Comparative Examples 1 to 4.

The above Examples 1 to 4 of the present invention and Comparative Examples 1 to 4
No. 4 was printed with a laser under each condition. Then, when the printing state was visually compared, the results shown in Table 1 below were obtained.

[0029]

[Table 1]

As a result of the above comparison, the thermosensitive recording media of Examples 1 to 4 of the present invention using Baytron can absorb energy efficiently because they are all excellent in conductivity.
It was confirmed that good printing was possible even with a low output laser.

Next, in order to compare the antistatic effect of the thermosensitive recording medium using Baytron P (manufactured by Bayer) with the thermosensitive recording medium not using Baytron, the same configuration as in Examples 1 to 4 above was used. Then, Baytron (B
ytron P (manufactured by Bayer AG)) were used, and two heat-sensitive recording media each having the structure of Comparative Examples 1-4 and Examples 1-4 were produced. The method of the comparative test of the antistatic effect is that two thermosensitive recording media are superimposed on each other, and a contact friction of 10 reciprocations is performed, and 25 mm from the media surface.
When the static electricity was measured according to the position, the measurement results shown in Table 2 below were obtained.

[0032]

[Table 2]

As a result of the above comparison, using Baytron,
It was confirmed that all of the heat-sensitive recording media of Examples 1 to 4 of the present invention hardly caused static electricity due to friction, and could simultaneously obtain an antistatic effect.

[0034]

As described in detail above, the heat-sensitive recording medium of the present invention comprises, in a heat-sensitive recording medium having a heat-sensitive recording layer formed on a substrate, the uppermost layer of the heat-sensitive recording layer or the heat-sensitive recording layer. Since the layer formed on top of the recording layer contains a conductive polymer, it also has an excellent antistatic effect,
There is an effect that dust and the like hardly adhere to the thermosensitive recording medium due to the influence of static electricity. In addition, the conductive polymer contains polythiophene, which is a conductive polymer, and enables recording and display using a laser.Moreover, since the conductive polymer is excellent in conductivity, energy can be efficiently absorbed and low energy can be absorbed. Since good printing is possible even with a laser having an output, good printing can be performed without increasing the output of the laser, so that there is an effect that a small-scale laser device is required. Therefore, as in the case of the conventional thermal recording medium, the thermal recording layer is brought into close contact with the thermal head, so that the thermal recording layer is physically damaged by the pressure of the thermal head, and traces of the previous print information remain. The problem will be solved.

[0035]

[Brief description of the drawings]

FIG. 1 is a sectional view of Example 1 of a thermosensitive recording medium of the present invention.

FIG. 2 is a sectional view of Example 2 of the thermosensitive recording medium of the present invention.

FIG. 3 is a sectional view of Example 3 of the thermosensitive recording medium of the present invention.

FIG. 4 is a sectional view of Example 4 of the thermosensitive recording medium of the present invention.

[Explanation of symbols]

 Reference Signs List 1a Thermal recording medium 1b Thermal recording medium 1c Thermal recording medium 1d Thermal recording medium 2 Base material 3 Aluminum vapor deposition layer 4 Liquid crystal dispersion film 5 Conductive layer 6 Base material 7 Thermal recording layer 8 Conductive layer 9 Base material 10 Aluminum vapor deposition layer 11 Reversible thermosensitive recording layer 12 Conductive layer 13 Substrate 14 Coloring layer 15 Deposition anchor layer 16 Tin vapor deposition layer 17 Conductive layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H026 AA07 AA24 DD01 DD48 DD53 DD55 2H111 HA00 HA14 HA23 HA35 4J032 BA04 BB01 BD07 CG00 CG01 CG03

Claims (3)

[Claims] 1. A heat-sensitive recording medium having a heat-sensitive recording layer formed on a base material, wherein the uppermost layer of the heat-sensitive recording layer contains a conductive polymer. 2. A thermosensitive recording medium in which a thermosensitive recording layer is formed on a substrate, wherein a layer containing a conductive polymer is formed on the thermosensitive recording layer. Medium. 3. The method according to claim 1, wherein the conductive polymer is a compound represented by the formula: In the formula, R ₁ and R ₂ are independently hydrogen or C ₁ ~ ₄ alkyl group, or the corresponding structural units to form a since it optionally an optionally substituted C ₁ ~ ₄ alkylene group with 3. The thermosensitive recording medium according to claim 1, wherein the thermosensitive recording medium is a dispersion of polythiophene.