JP2002337456A - Reversible heat sensitive recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reversible heat sensitive recording medium excellent in light resistance and durability. SOLUTION: In the reversible heat sensitive recording medium having a reversible heat sensitive recording layer including a reversible heat sensitive composition, in which an electron donable coloring compound and an electron acceptable compound are employed on a support so as to form a relatively color developed state due to the difference between heating speeds and/or of cooling speeds after heating, the recording medium has a protective layer including an ultraviolet absorbable polymer under crosslinked state and the glossiness of the surface of the medium is set to be 40% or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive coloring composition utilizing a coloring reaction between an electron-donating color-forming compound and an electron-accepting compound. The present invention relates to a reversible thermosensitive recording medium capable of forming and erasing.

[0002]

2. Description of the Related Art Conventionally, an electron-donating color-forming compound (hereinafter, referred to as an electron-donating color-forming compound) has been proposed.
Heat-sensitive recording media utilizing a color-forming reaction between a color former or a leuco dye and an electron-accepting compound (hereinafter also referred to as a developer) are widely known, such as a facsimile, a word processor, and a scientific measuring instrument. It has been widely used as an output sheet and recently as a thermal card having a magnetic storage unit such as a prepaid card or a point card. However, these conventional recording media that have been put into practical use all have irreversible color development, and it is not possible to erase an image once recorded and use it repeatedly.

[0003] On the other hand, according to the patent publication, a recording medium capable of reversibly performing coloring and decoloring has also been proposed.
For example, those using a combination of gallic acid and phloroglucinol as a color developer (Japanese Patent Laid-Open No. 60-193691)
And compounds using a compound such as phenolphthalein or thymolphthalein as a developer (Japanese Patent Laid-Open No.
JP-A-237684), a recording layer containing a homogeneous compatibilizer of a color former, a developer and a carboxylic acid ester (JP-A-62-138556, JP-A-62-13).
No. 8568, JP-A-62-140881), those using an ascorbic acid derivative as a color developer (described in JP-A-63-173684), and bis (hydroxyphenyl) acetic acid as a color developer Or a method using a salt of gallic acid and a higher aliphatic amine (JP-A-2-1882)
No. 93, JP-A-2-188294, etc.)
Are disclosed.

Further, the present inventors have disclosed in Japanese Patent Laid-Open No.
No. 4360, an organic phosphoric acid compound, an aliphatic carboxylic acid compound or a phenol compound having a long-chain aliphatic hydrocarbon group is used as a color developer, and color development and quenching are performed by combining this with a leuco dye as a color former. Color can be easily controlled by heating and cooling conditions, and its color-developed state and decolored state can be stably maintained at room temperature, and reversible thermosensitive color development that can repeat color development and decoloration A composition and a reversible thermosensitive recording medium using the same in a recording layer were proposed. Thereafter, the use of a specific structure for a phenol compound having a long-chain aliphatic hydrocarbon group (described in JP-A-6-210954) has been proposed.

A reversible thermosensitive recording medium manufactured using these materials can be colored by a thermal head or erased by a hot stamp or the like, and can be repeatedly colored / erased. However, these reversible thermosensitive recording media have durability and light resistance such that dents and scratches are caused by repeated printing and erasing under practical conditions, or the leuco dye is deteriorated and colored by light. Had a problem in terms of

To solve such a problem, Japanese Patent Laid-Open Publication No.
Japanese Patent Application Laid-Open No. 4960 and Japanese Patent Application Laid-Open No. 9-207439 describe a method of adding a polymer having an ultraviolet absorbing structure to a protective layer. However, these methods have a problem in that dents are generated by using them many times, and the number of times of repeated use is limited to a small number of times. The reason for this is that, in these methods, the heat resistance is insufficient because the ultraviolet absorbing polymer used is not in a cross-linked state, so that the medium deteriorates greatly when the heat energy required for printing is applied, It is thought that dents will occur. JP-A-2001-30630 describes the use of a specific ultraviolet absorber capable of crosslinking with an isocyanate compound. However, since the UV absorber is a low molecular weight compound, if a large amount of the UV absorber is added to obtain sufficient light resistance, uncrosslinked ones remain and bleed out, or even repeat. When printing or erasing is performed, there is a problem that color development and decoloring are adversely affected. It is also possible to reduce these problems by reducing the amount of uncrosslinked low molecular weight UV absorber by using a large amount of crosslinking agent to crosslink the low molecular weight UV absorber, Since the amount of the resin component and the like is reduced, the durability and heat resistance of the layer are reduced, and a problem occurs when the layer is repeatedly used. In addition, when the addition amount was reduced to such an extent that these problems did not occur, the background portion was colored by light such as sunlight and the like, which was not satisfactory. Because of these problems, a reversible thermosensitive recording medium that satisfies both light resistance and durability has not been provided.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a reversible thermosensitive recording medium which is excellent in light resistance and durability.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve these problems, and as a result,
It has been found that these problems can be solved when an ultraviolet absorbing polymer is used in the recording medium and the glossiness of the recording medium surface is 40% or less. That is, a reversible heat-sensitive composition which can form a relatively colored state by using an electron-donating color-forming compound and an electron-accepting compound on a support and heating and / or a cooling rate after heating is contained. Reversible thermosensitive recording medium having a reversible thermosensitive recording layer
A reversible thermosensitive recording medium having excellent light resistance and repetition durability when a UV absorbing polymer is used in the recording medium and the polymer is in a crosslinked state and the glossiness of the recording medium surface is 40% or less. Was obtained. The glossiness of the recording medium surface in the present invention is defined by JIS
It is obtained by a specular gloss measurement method based on the Z8741 method at 60 degrees incidence.

Second, it has been found that these problems can be solved when an ultraviolet absorbing polymer is used in the recording medium and the friction coefficient of the recording medium surface is 0.2 or less. That is, a reversible heat-sensitive composition which can form a relatively colored state by using an electron-donating color-forming compound and an electron-accepting compound on a support and heating and / or a cooling rate after heating is contained. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer, a UV-absorbing polymer is used in the recording medium, and when the friction coefficient of the recording medium surface is 0.2 or less, light resistance and repetition durability are excellent. It has been found that a reversible thermosensitive recording medium can be obtained.

Third, it has been found that these problems can be solved by using an ultraviolet absorbing polymer having a hydroxyl value of 20 or more. That is, a reversible heat-sensitive composition which can form a relatively colored state by using an electron-donating color-forming compound and an electron-accepting compound on a support and heating and / or a cooling rate after heating is contained. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer, a reversible thermosensitive recording medium excellent in light resistance and repetition durability can be obtained by containing an ultraviolet absorbing polymer having a hydroxyl value of 20 or more. I found

Therefore, the above-mentioned object is achieved by the following first group of the present invention, second group of the present invention, and third group of the present invention. That is, the above-mentioned problem is solved by the first group of the present invention (1) using an electron-donating color-forming compound and an electron-accepting compound on a support, and heating and / or the cooling rate after heating is relatively different. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a reversible thermosensitive composition capable of forming a colored state, the reversible thermosensitive recording medium has a protective layer containing a UV-absorbing polymer in a cross-linked state, and has a surface glossiness. Is reversible thermosensitive recording medium characterized in that the protective layer has an organic and / or inorganic filler in the protective layer. Reversible thermosensitive recording medium ",
(3) The reversible thermosensitive recording medium according to the above (2), wherein the content of the filler is 5 to 50 in terms of solid content relative to 100 parts by weight of the protective layer resin. 4)
“The reversible thermosensitive recording medium according to the above (2) or (3), wherein the filler is coated with calcium”, (5) “The thermoreversible recording unit and the information storage unit The reversible thermosensitive recording medium according to any one of the above items (1) to (4), "
(6) The reversible thermosensitive recording medium according to (5), wherein the information storage unit is at least one of a magnetic recording layer, a magnetic stripe, an IC memory, and an optical memory. Achieved.

Another object of the present invention is to provide the second group of the invention (7), wherein the difference between the heating rate and / or the cooling rate after heating is obtained by using an electron-donating color-forming compound and an electron-accepting compound on a support. In a reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a reversible thermosensitive composition capable of forming a relatively colored state by, having a protective layer containing a UV-absorbing polymer in a cross-linked state, A reversible thermosensitive recording medium having a surface friction coefficient of 0.2 or less ",
(8) “The reversible thermosensitive recording medium according to the above (7), wherein the protective layer contains a silicon graft polymer”, (9) “The silicon graft polymer is in a crosslinked state. (10) The reversible thermosensitive recording medium according to the above (8), wherein the ultraviolet absorbing polymer and / or the silicon graft polymer is cross-linked by isocyanate. (7) The reversible thermosensitive recording medium according to any one of the above items (9) to (9), (11) wherein the protective layer contains the ultraviolet absorbing polymer. ) To (10), the reversible thermosensitive recording medium according to any one of the above (10) to (12), wherein the recording medium includes a thermoreversible recording section and an information storage section. Item (11) (13) The information storage section is at least one of a magnetic recording layer, a magnetic stripe, an IC memory, and an optical memory. )), (14) “the surface glossiness is 4
The reversible thermosensitive recording medium according to any one of the above items (7) to (13), wherein the content is 0% or less. "
Achieved by

The above object is also achieved by the third group of the present invention (1).
5) A reversible thermosensitive composition capable of forming a relatively colored state by heating and / or a difference in cooling rate after heating using an electron-donating color-forming compound and an electron-accepting compound on a support. A reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing, containing a UV-absorbing polymer having a hydroxyl value of 20 or more, wherein the polymer is in a cross-linked state, (16) The above-mentioned (1), wherein the protective layer is further provided on the reversible thermosensitive recording layer, and the polymer is contained in the protective layer.
(17) The reversible thermosensitive recording medium according to the above (15) or (16), wherein the ultraviolet absorbing polymer has a Tg of 50 ° C. or more. Thermosensitive recording medium ", (18)" (15) to (17), wherein the content of the ultraviolet absorbing component of the ultraviolet absorbing polymer is 50% or more. (19) The reversible thermosensitive recording medium according to any one of the above (15) to (18), wherein the weight average molecular weight of the ultraviolet absorbing polymer is 10,000 or more. Thermal recording medium ", (20)
"The reversible thermosensitive recording medium according to any one of the above items (15) to (18), wherein the ultraviolet absorbing component of the ultraviolet absorbing polymer has a benzotriazole skeleton", ( 21) “The reversible thermosensitive recording medium according to any one of the above items (15) to (20), wherein the ultraviolet absorbing polymer is in a crosslinked state by an isocyanate compound”; The reversible thermosensitive recording medium according to the above item (21), wherein the isocyanate compound is an adduct type, a burette type, or a trimer type of hexamethylene diisocyanate, (23) (15) to (2), characterized by having an information storage unit.
2) The reversible thermosensitive recording medium according to any one of the item 1);
(24) “The reversible thermosensitive recording medium according to (23), wherein the information storage unit is at least one of a magnetic recording layer, a magnetic stripe, an IC memory, and an optical memory”; (25) The items (15) to (2), wherein the glossiness of the surface is 40% or less.
4) The reversible thermosensitive recording medium according to any one of the above items),
(26) The reversible thermosensitive recording medium according to the above (25), wherein the coefficient of friction of the surface is 0.2 or less.

Hereinafter, the reversible thermosensitive recording medium of the present invention will be described in detail. [First Group of the Invention] The first group of the reversible thermosensitive recording media of the present invention has excellent light resistance and durability by using a crosslinked ultraviolet absorbing polymer as described above. Becomes Furthermore, the present inventors have conducted various studies and found that when the glossiness is 40% or less, the durability becomes particularly excellent.

In the first group of the reversible thermosensitive recording medium of the present invention, the glossiness of the medium surface is determined by the type of the resin used. As a result, the glossiness can be reduced. Conversely, when increasing the gloss, the amount of addition may be reduced or the particle size may be reduced. In the present invention, reversible thermosensitive recording media having various gloss levels are manufactured and evaluated by examining these conditions, and it is found that when the gloss level of the recording medium surface is 40% or less, light resistance and durability are excellent. Was.

As the ultraviolet absorbing polymer used in the first group of the present invention, a polymer which can be crosslinked by heat, ultraviolet rays, electron beams or the like is used, and a polymer containing a hydroxyl group which can be crosslinked by isocyanate is particularly preferable. Also,
Examples of the ultraviolet absorbing structure contained in the ultraviolet absorbing polymer used in the first group of the present invention include a salicylate structure, a cyanoacrylate structure, a benzotriazole structure and a benzophenone structure, and preferably a benzophenone structure and a benzotriazole structure. Is used, and particularly preferably has a benzotriazole structure.

Further, in the reversible thermosensitive recording medium of the present invention, when the ultraviolet absorbing polymer is in a cross-linked state by the isocyanate compound, the recording medium becomes more excellent in durability. As the isocyanate compound, an adduct type, a burette type, or a trimer type of hexamethylene diisocyanate is preferably used. Here, it was found that durability was unexpectedly improved by limiting the glossiness of the medium surface to 40% or less. It is considered that this is because the matching property with the heat generating head is improved, and the erasing traces and dents are less noticeable.

Further, the reversible thermosensitive recording medium of the present invention has a good matching property between the surface of the recording medium and a device for coloring the recording medium by containing a filler in the protective layer, and has excellent durability. Become. As the filler used in the present invention, either or both of an organic filler and an inorganic filler may be used at the same time, but preferably silica is used, and particularly preferably calcium-coated or composite silica particles are used. .

The basic skeleton of the polymer having an ultraviolet absorbing structure used in the present invention is a copolymer of a monomer having an ultraviolet absorbing group and a monomer having a functional group. The polymerization forms include linear polymers, branched polymers, star polymers, comb polymers, dendritic polymers, cyclic polymers, catena polymers, and the like. As long as it is a copolymer, any of a block copolymer, a graft copolymer, a star-shaped copolymer, and a random copolymer may be used. Polymers are particularly preferably used.

The ultraviolet absorbing group contained in the ultraviolet absorbing polymer used in the present invention preferably has a benzophenone structure or a benzotriazole structure.
Particularly preferably, those having a benzotriazole structure are used. Of these, specific examples of the benzophenone structure include, but are not limited to, 2-hydroxy-
4-acryloyloxybenzophenone, 2-hydroxy-4- (2-acryloyloxy) ethoxybenzophenone, 2-hydroxy-4- (2-methacryloyloxy) ethoxybenzophenone, 2-hydroxy-4-
Examples include methacryloyloxybenzophenone, 2-hydroxy-4- (2-methyl-2-acryloyloxy) ethoxybenzophenone, and 2,2 ′, 4,4′-tetrahydroxybenzophenone.

Specific examples of the benzotriazole structure include 2- [2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -2H-benzotriazole,
2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2
-[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-t-butyl-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxy) phenyl] benzotriazole, −
[2'-hydroxy-5 '-(acryloyloxy) phenyl] benzotriazole, 2- [2'-hydroxy-3'-t-butyl-5'-(methacryloyloxy)
Phenyl] benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyhexyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-t-butyl-3'-(methacryloyloxy Ethyl) phenyl] -2H-benzotriazole, 2-
[2'-hydroxy-3'-methyl-5 '-(acryloyloxy) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -5-chlorobenzotritriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2'-hydroxy-5'-(acryloyloxyethyl) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-methoxy-2H -Benzotriazole, 2- [2'-hydroxy-3'-t-
Butyl-5 '-(methacryloyloxyethyl) phenyl] benzotriazole, 2- [2'-hydroxy-
3'-methyl-5 '-(acryloyloxyethyl) phenyl] benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxypropyl) phenyl]
-5-chlorobenzotriazole, 2- [2'-hydroxy-5 '-(acroyloxybutyl) phenyl]-
5-methylbenzotriazole, [2-hydroxy-3
-T-butyl-5- (acryloyloxyethoxycarbonylethyl) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-nitro-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacrylyloxyloxyethyl) phenyl] -2H-benzo Examples thereof include, but are not limited to, triazole and 2- (2-hydroxy-5-methylphenyl) benzotriazole.

Examples of the monomer containing a functional group include, for example, 2
-Isopropenyl-2-oxazoline, 2-aziridinylethyl (meth) acrylate, methacrylic acid, glycidyl (meth) acrylate, hydroxymethyl (meth)
Acrylate, hydroxylethyl (meth) acrylate, hydroxypropyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, etc. Among them, hydroxylethyl (meth) acrylate, hydroxypropyl methacrylate and the like are particularly preferably used.

Further, in order to improve the coating strength and heat resistance,
The following monomers may be copolymerized with a copolymer of a monomer having an ultraviolet absorbing group and a monomer having a functional group. For example, styrene, methyl methacrylate, styrene-butadiene, styrene-isobutylene, ethylene vinyl acetate, vinyl acetate, methacrylonitrile, vinyl alcohol, vinyl prolidone, acrylonitrile and other monomer groups, acrylic acid, acrylic acid ester, methacrylic acid ester, Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, Cyclohexyl (meth) acrylate, benzyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, ethylhexyl (meth) acrylate, Ethylene di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate,
Tetraethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate phthalate, pentaerythritol tetra (meth) acrylate, pentaerythritol hexa (meth) acrylate , Dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol penta (meth) acrylate, phosphazene hexa (meth) acrylate, and the like, but are not limited thereto. . Preferably, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, or the like is used. If necessary, two or more kinds can be used in combination. In particular, an ultraviolet absorbing polymer having a hydroxyl group by copolymerizing hydroxyethyl (meth) acrylate or the like is preferable. Can be used after being crosslinked.

The first group of organic compounds used in the present invention
As examples of the inorganic filler, conventionally known organic / inorganic fillers are used alone or in combination. Preferably, the organic filler includes, for example, a silicon-based filler, a fluorine-based filler, an acrylic-based filler, a polyamide-based filler, an epoxy resin filler, a thermosetting resin hollow sphere, a polyethylene wax, a shellac, a wood powder, a cork powder, and the like. . As the inorganic filler, silica, alumina, zinc oxide, indium oxide, zirconia oxide, tin oxide, cerium oxide, iron oxide, antimony oxide, barium oxide,
Calcium oxide, barium oxide, bismuth oxide, nickel oxide, magnesium oxide, chromium oxide, manganese oxide, tantalum oxide, niobium oxide, thorium oxide, hafnium oxide, molybdenum oxide, iron ferrite, nickel ferrite, cobalt ferrite, barium titanate, titanium Metal oxides such as potassium acid; calcium carbonate;
Carbonates such as magnesium carbonate; silicates such as silicic anhydride, hydrous silicic acid, hydrous aluminum silicate and hydrous calcium silicate; hydroxides such as alumina and iron oxide; zinc sulfide and barium sulfate Metal sulfide or sulfate compound; metal carbide such as titanium carbide, silicon carbide, molybdenum carbide, tungsten carbide, tantalum carbide; aluminum nitride, silicon nitride, boron nitride, zirconium nitride, vanadium nitride, titanium nitride, niobium nitride, gallium nitride Metallic nitride, talc, kaolin, clay, etc., are preferred, but inorganic fillers are preferably used from the viewpoint of durability, and are particularly preferably coated or complexed with calcium in view of the effect on color development / decoloration characteristics. An inorganic filler is used.

The leuco dye used in the present invention includes:
One or more compounds used in this type of reversible thermosensitive recording medium can be used, and examples thereof include known dye precursors such as phthalide compounds, azaphthalide compounds, and fluoran compounds.

A typical example of a color developer used in the recording layer is disclosed in, for example, JP-A-5-124360.
JP, JP-A-6-210954 and JP-A-10-210
Compounds described in, for example, US Pat. The color developing agent used herein has a structure having a color developing ability to develop a leuco dye in the molecule, such as a phenolic hydroxyl group, a carboxylic acid group, a phosphoric acid group, and a structure controlling the cohesive force between the molecules, for example, a length. A compound having one or more structures in which chain hydrocarbon groups are linked. The linking moiety may be via a divalent or higher linking group containing a hetero atom, and the long chain hydrocarbon group may contain the same linking group and / or aromatic group. Specific examples of such a reversible developer are described in, for example, JP-A-9-290563 and JP-A-11-188969.

FIG. 1 shows the relationship between the color density and the temperature of the reversible thermosensitive recording medium of the present invention. A reversible recording layer using these leuco dyes and a developer develops and decolors in the process shown in FIG. Initial decolored state (A)
Leuco dye and the developer are colored by mixing melted at a temperature above T ₁ Heating the (B), the colored state is fixed to quench this state. Heating the color-developed state (C), and decolored at a lower temperature T ₂ than the coloring temperature, the initial and the same decolored state if cooled.

As described above, the recording layer can be recorded and erased by controlling the heating temperature and the cooling rate after the heating. Printing with this recording layer provides high contrast and excellent image quality. In addition, it has excellent storage stability and durability against repeated printing and erasure, and is particularly suitable as the reversible thermosensitive recording medium of the present invention. Printing on a reversible recording medium using this recording layer can be performed with a thermal head in the same manner as normal thermal recording, and erasing can be performed with a temperature-controlled heat roller, a heating element such as a ceramic heater, and a thermal head. It can be used with a small and simple recording device.

The reversible thermosensitive recording medium of the present invention forms a recording layer together with a leuco dye, a color developer and a coloring / decoloring controlling agent together with a resin. The resin used at this time only needs to be able to bind these materials on the support, and conventionally known resins are widely used. Above all, in order to improve the durability at the time of repetition, a resin curable by heat, ultraviolet rays, electron beams, or the like is preferably used, and a thermosetting resin using an isocyanate compound or the like as a crosslinking agent is particularly preferably used. .

Further, in the present invention, an improvement in color development sensitivity,
An under layer, a protective layer, a back layer, and the like may be provided for improving durability and light resistance. In these layers, together with a resin, an organic / inorganic filler, an ultraviolet absorber, a lubricant, and coloring are provided. Although a pigment or the like can be used, when the silicon graft polymer is contained in the protective layer, the reversible thermosensitive recording medium of the present invention has particularly excellent durability.

As the support of the reversible thermosensitive recording medium of the present invention, it is sufficient that the recording layer can be retained, and paper, synthetic paper, PET film and the like are preferably used. Further, the support may be attached to another material via these supports.

The reversible thermosensitive recording medium of the present invention is provided with both a thermoreversible recording section and an information recording section, so that information stored in the information storage section is displayed on the thermoreversible recording section. Information can be checked without any equipment.
Convenience is improved. As the storage unit used at that time, a magnetic recording layer, a magnetic stripe, an IC recording unit, an optical memory, or the like is preferably used.

Further, these can be processed into a shape according to the use, and are processed into a card shape, a sheet shape, a roll shape and the like. Cards processed into prepaid cards, point cards, and credit cards, etc., and those processed into sheets are printed when processed into general document size such as A4 size. By using the / erase device, it can be widely used not only for trial printing, but also for temporary output such as circular documents and conference materials. Furthermore, the material processed into a roll shape can be used for a display board, a bulletin board, or an electronic blackboard, for example, by being incorporated in a device having a printing / erasing unit. Since such a display device does not generate dust and dirt, it can be preferably used in a clean room or the like.

[Second group of the present invention] The reversible thermosensitive recording medium of the second group of the present invention has improved light fastness and durability by using an ultraviolet absorbing polymer in a cross-linked state as described above. However, when the friction coefficient of the recording medium surface is set to 0.2 or less, the durability is further improved. The present inventors changed the conditions such as the type of the resin of the surface layer, the type and the amount of the filler, and the particle size, and further, the recording having the surface characteristics with different friction coefficients depending on the amount of the silicon graft polymer added. Various media were prepared and studied. As a result, in the reversible thermosensitive recording medium of the present invention, when the dynamic friction coefficient of the recording medium surface is 0.2 or less, occurrence of dents and change in color density during repeated printing are not observed, and the durability of the medium is significantly improved. I found something to do. This is considered to be because the contact portion can be conveyed without resistance when the recording medium comes into contact with the heat generating device for coloring the recording medium, so that the recording medium has excellent durability.

As the ultraviolet absorbing polymer used in the second group of the present invention, a polymer crosslinkable by heat, ultraviolet rays, electron beams or the like is used, and a polymer containing a hydroxyl group crosslinkable by isocyanate is particularly preferable. Also,
Examples of the ultraviolet absorbing structure contained in the ultraviolet absorbing polymer used in the second group of the present invention include a salicylate structure, a cyanoacrylate structure, a benzotriazole structure and a benzophenone structure, and preferably a benzophenone structure and a benzotriazole structure Is used, and particularly preferably has a benzotriazole structure.

Further, also in the reversible thermosensitive recording medium of the second group of the present invention, when the ultraviolet absorbing polymer is in a crosslinked state by an isocyanate compound, the durability is further improved. As the isocyanate compound, an adduct type, a burette type, or a trimer type of hexamethylene diisocyanate is preferably used.

Also, by using the silicon graft polymer for the protective layer, the second group of the reversible thermosensitive recording media of the present invention also has more excellent durability. As the silicone graft polymer, a silicone graft acrylic polymer, a silicone graft modified polyvinyl alcohol and the like are preferably used. Above all, heat, ultraviolet rays,
A polymer that can be crosslinked by an electron beam or the like is particularly preferably used, and when the polymer is in a crosslinked state, the second group of the reversible thermosensitive recording media of the present invention has excellent durability.

The dynamic friction coefficient of the second group of the present invention is measured by the following method. The measurement was performed using a static / dynamic friction coefficient measuring device (manufactured by Kyowa Interface Science Co., Ltd.). The settings at that time were as follows: a surface contact (1 cm ² ), a load of 400 g, a stroke of 30 mm, and a moving speed of 0.5 mm / s.
The coefficient of dynamic friction was determined by averaging five times.

The basic skeleton of the polymer having an ultraviolet absorbing structure used in the second group of the present invention is a copolymer of a monomer having an ultraviolet absorbing group and a monomer having a functional group. The polymerization forms include linear polymers, branched polymers, star polymers, comb polymers, dendritic polymers, cyclic polymers, catena polymers, and the like. And if it is a copolymer, it may be any of a block copolymer, a graft copolymer, a star copolymer, and a random copolymer, and is not particularly limited,
Among them, block copolymers and graft copolymers are particularly preferably used.

The UV-absorbing group contained in the UV-absorbing polymer used in the second group of the present invention preferably has a benzophenone structure or a benzotriazole structure, particularly preferably a benzotriazole structure. Things are used. Among them, specific examples of the benzophenone structure are not limited to these, but
-Hydroxy-4-acryloyloxybenzophenone, 2-hydroxy-4- (2-acryloyloxy)
Ethoxybenzophenone, 2-hydroxy-4- (2-
Methacryloyloxy) ethoxybenzophenone, 2-
Hydroxy-4-methacryloyloxybenzophenone, 2-hydroxy-4- (2-methyl-2-acryloyloxy) ethoxybenzophenone, 2,2 ′, 4,
4'-tetrahydroxybenzophenone and the like.

Similarly, specific examples of the benzotriazole structure include 2- [2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -2H-benzotriazole and 2- [2'-hydroxy-5'- (Methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-t-butyl-2H-benzotriazole, 2- [2'-hydroxy -5'-
(Methacryloyloxy) phenyl] benzotriazole, 2- [2'-hydroxy-5 '-(acryloyloxy) phenyl] benzotriazole, 2- [2'-hydroxy-3'-t-butyl-5'-(methacryloyloxy ) Phenyl] benzotriazole, 2- [2′-
Hydroxy-5 '-(methacryloyloxyhexyl)
Phenyl] -2H-benzotriazole, 2- [2′-
Hydroxy-5'-t-butyl-3 '-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-3'-methyl-5'-
(Acryloyloxy) phenyl] benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -5-chlorobenzotritriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) ) Phenyl] benzotriazole,
2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2'-hydroxy-5'-(acryloyloxyethyl) phenyl] benzotriazole,
-[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-methoxy- 2H-benzotriazole, 2- [2'-hydroxy-3'-t
-Butyl-5 '-(methacryloyloxyethyl) phenyl] benzotriazole, 2- [2'-hydroxy-
3'-methyl-5 '-(acryloyloxyethyl) phenyl] benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxypropyl) phenyl]
-5-chlorobenzotriazole, 2- [2'-hydroxy-5 '-(acroyloxybutyl) phenyl]-
5-methylbenzotriazole, [2-hydroxy-3
-T-butyl-5- (acryloyloxyethoxycarbonylethyl) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-nitro-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacrylyloxyloxyethyl) phenyl] -2H-benzo Examples thereof include, but are not limited to, triazole and 2- (2-hydroxy-5-methylphenyl) benzotriazole.

Examples of the monomer containing a functional group include, for example, 2-isopropenyl-2-oxazoline, 2-aziridinylethyl (meth) acrylate, methacrylic acid,
Glycidyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxylethyl (meth) acrylate, hydroxypropyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) Acrylate, tetrahydrofurfuryl (meth) acrylate and the like can be mentioned, and among them, hydroxylethyl (meth) acrylate, hydroxypropyl methacrylate and the like are particularly preferably used.

Further, in order to improve the strength of the coating film and the heat resistance, the following monomers are similarly copolymerized with a copolymer of a monomer having an ultraviolet absorbing group and a monomer having a functional group. You may. For example, styrene, methyl methacrylate, styrene-butadiene, styrene-isobutylene, ethylene vinyl acetate, vinyl acetate, methacrylonitrile, vinyl alcohol, vinyl prolidone, acrylonitrile and other monomer groups, acrylic acid, acrylic acid ester, methacrylic acid ester, Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth)
Acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, ethylhexyl (meth) Acrylate, isoethylene di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate,
Tetraethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate phthalate, pentaerythritol tetra (meth) acrylate, pentaerythritol hexa (meth) acrylate , Dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol penta (meth) acrylate, phosphazene hexa (meth) acrylate, and the like, but are not limited thereto. . Preferably, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, or the like is used. If necessary, two or more kinds can be used in combination. In particular, an ultraviolet absorbing polymer having a hydroxyl group by copolymerizing hydroxyethyl (meth) acrylate or the like is preferable. Can be used after being crosslinked.

As the leuco dye used in the second group of the present invention, one or more compounds used in this kind of reversible thermosensitive recording medium can be used.
It is a known dye precursor such as a phthalide compound, an azaphthalide compound or a fluoran compound.

As a representative example of the color developer used in the recording layer, for example, Japanese Patent Application Laid-Open No. 5-124360
JP, JP-A-6-210954 and JP-A-10-210
Compounds described in, for example, US Pat. The color developing agent used herein has a structure having a color developing ability to develop a leuco dye in the molecule, such as a phenolic hydroxyl group, a carboxylic acid group, a phosphoric acid group, and a structure controlling the cohesive force between the molecules, for example, a length. A compound having one or more structures in which chain hydrocarbon groups are linked. The linking moiety may be via a divalent or higher linking group containing a hetero atom, and the long chain hydrocarbon group may contain the same linking group and / or aromatic group. Specific examples of such a reversible developer include, for example, JP-A-9-290563,
This is disclosed in JP-A-11-188969.

The relationship between the color density and the temperature of the reversible thermosensitive recording medium shown in FIG. 1 is also applied to the case of the second group of the present invention. Can be. Printing with this recording layer provides high contrast and excellent image quality. In addition, it has excellent storage stability and durability against repeated printing and erasure, and is particularly suitable as the reversible thermosensitive recording medium of the present invention. Printing on a reversible recording medium using this recording layer can be performed with a thermal head in the same manner as normal thermal recording, and erasing can be performed with a temperature-controlled heat roller, a heating element such as a ceramic heater, and a thermal head. It can be used with a small and simple recording device.

The second group of the reversible thermosensitive recording media of the present invention also comprises
The leuco dye, the color developer and the coloring / decoloring controlling agent form a recording layer together with the resin. The resin used at this time only needs to be able to bind these materials on the support, and conventionally known resins are widely used. Above all, in order to improve the durability at the time of repetition, a resin curable by heat, ultraviolet rays, electron beams, or the like is preferably used, and a thermosetting resin using an isocyanate compound or the like as a crosslinking agent is particularly preferably used. .

In the second group of the present invention, an under layer, a protective layer, a back layer, and the like may be provided in order to improve color sensitivity, durability, and light resistance. In addition to the resin, an organic / inorganic filler, an ultraviolet absorber, a lubricant, a coloring pigment, and the like can be used. When the UV-absorbing polymer is used in the protective layer, the reversible thermosensitive recording medium of the present invention has excellent light fastness and durability, and when the silicone graft polymer is contained in the protective layer, The two groups of the reversible thermosensitive recording media of the present invention have particularly excellent durability. Although the ultraviolet absorbing polymer and the silicon graft polymer may be used independently in the protective layer, it is preferable that both polymers are included in the protective layer together.

The support of the reversible thermosensitive recording medium of the second group of the present invention may be any as long as it can hold the recording layer, and preferably, paper, synthetic paper, PET film or the like is used. Further, the support may be attached to another material via these supports.

The second group of the reversible thermosensitive recording media of the present invention also comprises
By providing both the thermoreversible recording section and the information recording section, the information stored in the information storage section can be displayed on the thermoreversible recording section so that the information can be confirmed without a special device. , Convenience is improved. As the storage unit used at that time, a magnetic recording layer, a magnetic stripe, an IC recording unit, an optical memory, or the like is preferably used.

[0051] Similarly, these can be processed into a shape according to the application, and may be a card, a sheet,
It is processed into a roll or the like. Cards processed into prepaid cards, point cards, and credit cards, etc., and those processed into sheets are printed when processed into general document size such as A4 size. By using the / erase device, it can be widely used not only for trial printing, but also for temporary output such as circular documents and conference materials. Furthermore, the material processed into a roll shape can be used for a display board, a bulletin board, or an electronic blackboard, for example, by being incorporated in a device having a printing / erasing unit. Since such a display device does not generate dust and dirt, it can be preferably used in a clean room or the like.

[Third Group of the Invention] As described above, the ultraviolet absorbing polymer used in the reversible thermosensitive recording medium of the third group of the present invention has the ultraviolet absorbing ability of the ultraviolet absorbing group contained in the polymer. It has the film forming ability of the polymer itself,
When the polymer is in a crosslinked state, the polymer has excellent durability. Furthermore, the present inventors can obtain a sufficient coating film strength by using a polymer having a hydroxyl value of 20 or more as the UV-absorbing polymer, and the occurrence of dents and a change in concentration during repeated use are not observed. The media has been found to have particularly good durability. This is presumably because the polymer having a high hydroxyl value has a sufficient crosslinking point.

Further, when a polymer having a Tg of 50 ° C. or higher is used, the third group of the reversible thermosensitive recording media of the present invention is more excellent in durability. When an ultraviolet absorbing polymer having an ultraviolet absorbing component content of 50% by weight or more is used as the ultraviolet absorbing polymer, a reversible thermosensitive recording medium having excellent light resistance can be obtained. The third group of the ultraviolet absorbing polymer used in the present invention has a weight average molecular weight of 10
When the weight average molecular weight of the polymer is 10,000 or more, the third group of the reversible thermosensitive recording media of the present invention has excellent durability. Such an ultraviolet absorbing polymer can increase light fastness and durability when used in any layer of the reversible thermosensitive recording medium of the third group of the present invention. Significantly increase the performance.

Examples of the UV absorbing structure contained in the UV absorbing polymer used in the third group of the present invention include a salicylate structure, a cyanoacrylate structure, a benzotriazole structure and a benzophenone structure. Those having a benzotriazole structure are used, and particularly preferably those having a benzotriazole structure are used.

Further, in the reversible thermosensitive recording medium of the third group of the present invention, when the ultraviolet absorbing polymer is in a crosslinked state by an isocyanate compound, the durability is further improved. As the isocyanate compound, an adduct type, a burette type, or a trimer type of hexamethylene diisocyanate is preferably used.

The basic skeleton of the polymer having an ultraviolet absorbing structure used in the third group of the present invention is a copolymer of a monomer having an ultraviolet absorbing group and a monomer having a functional group. The polymerization forms include linear polymers, branched polymers, star polymers, comb polymers, dendritic polymers, cyclic polymers, catena polymers, and the like. And if it is a copolymer, it may be any of a block copolymer, a graft copolymer, a star copolymer, and a random copolymer, and is not particularly limited,
Among them, block copolymers and graft copolymers are particularly preferably used.

As the ultraviolet absorbing group contained in the ultraviolet absorbing polymer used in the third group of the present invention, those having a benzophenone structure or a benzotriazole structure are preferably used, and those having a benzotriazole structure are particularly preferable. Can be Among these, specific examples of the benzophenone structure include, but are not limited to, 2-hydroxy-4-acryloyloxybenzophenone, 2-hydroxy-4- (2-acryloyloxy) ethoxybenzophenone, and 2-hydroxy-4. -(2-methacryloyloxy) ethoxybenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone, 2-hydroxy-4- (2-methyl-2-acryloyloxy)
Ethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like can be mentioned.

Specific examples of the benzotriazole structure include 2- [2'-hydroxy-5 '-(methacryloyloxymethyl) phenyl] -2H-benzotriazole and 2- [2'-hydroxy-5'-( (Methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-t-butyl-2H-benzotriazole, 2- [2'-hydroxy- 5 '-(methacryloyloxy) phenyl] benzotriazole,
2- [2'-hydroxy-5 '-(acryloyloxy) phenyl] benzotriazole, 2- [2'-hydroxy-3'-t-butyl-5'-(methacryloyloxy) phenyl] benzotriazole, 2- [ 2'-hydroxy-5 '-(methacryloyloxyhexyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-t-butyl-3'-(methacryloyloxyethyl) phenyl] -2H-benzo Triazole,
2- [2'-hydroxy-3'-methyl-5 '-(acryloyloxy) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -5-chlorobenzotritriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2'-hydroxy-5'-(acryloyloxyethyl) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxyethyl) phenyl] -5-methoxy-2H -Benzotriazole, 2- [2'-hydroxy-3'-t-
Butyl-5 '-(methacryloyloxyethyl) phenyl] benzotriazole, 2- [2'-hydroxy-
3'-methyl-5 '-(acryloyloxyethyl) phenyl] benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxypropyl) phenyl]
-5-chlorobenzotriazole, 2- [2'-hydroxy-5 '-(acroyloxybutyl) phenyl]-
5-methylbenzotriazole, [2-hydroxy-3
-T-butyl-5- (acryloyloxyethoxycarbonylethyl) phenyl] benzotriazole, 2-
[2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-nitro-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacrylyloxyloxyethyl) phenyl] -2H-benzo Examples thereof include, but are not limited to, triazole and 2- (2-hydroxy-5-methylphenyl) benzotriazole.

As the monomer containing a functional group, for example, similarly, 2-isopropenyl-2-oxazoline, 2-aziridinylethyl (meth) acrylate, methacrylic acid,
Glycidyl (meth) acrylate, hydroxymethyl (meth) acrylate, hydroxylethyl (meth) acrylate, hydroxypropyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) Acrylate, tetrahydrofurfuryl (meth) acrylate and the like can be mentioned, and among them, hydroxylethyl (meth) acrylate, hydroxypropyl methacrylate and the like are particularly preferably used.

Further, in order to improve the coating film strength and heat resistance,
Similarly, the following monomers may be copolymerized with a copolymer of a monomer having an ultraviolet absorbing group and a monomer having a functional group. For example, styrene, methyl methacrylate, styrene-butadiene, styrene-isobutylene, ethylene vinyl acetate, vinyl acetate, methacrylonitrile, vinyl alcohol, vinyl prolidone, acrylonitrile and other monomer groups, acrylic acid, acrylic acid ester, methacrylic acid ester, Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth)
Acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, ethylhexyl (meth) Acrylate, isoethylene di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate,
Tetraethylene glycol di (meth) acrylate, hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate phthalate, pentaerythritol tetra (meth) acrylate, pentaerythritol hexa (meth) acrylate , Dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol penta (meth) acrylate, phosphazene hexa (meth) acrylate, and the like, but are not limited thereto. . Preferably, styrene, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, or the like is used. Further, if necessary, two or more kinds can be used in combination. In particular, an ultraviolet absorbing polymer having a hydroxyl group by copolymerizing hydroxyethyl (meth) acrylate or the like is preferable, and these are combined with an isocyanate-based crosslinking agent as described above. It can be used after crosslinking.

Similarly, as the leuco dyes used in the third group of the present invention, one or more compounds used in this type of reversible thermosensitive recording medium can be used. For example, phthalide compounds, azaphthalide compounds And known dye precursors such as fluoran compounds.

A typical example of a developer used in the recording layer is disclosed in, for example, JP-A-5-124360.
JP, JP-A-6-210954 and JP-A-10-210
Compounds described in, for example, US Pat. The color developing agent used herein has a structure having a color developing ability to develop a leuco dye in the molecule, such as a phenolic hydroxyl group, a carboxylic acid group, a phosphoric acid group, and a structure controlling the cohesive force between the molecules, for example, a length. A compound having one or more structures in which chain hydrocarbon groups are linked. The linking moiety may be via a divalent or higher linking group containing a hetero atom, and the long chain hydrocarbon group may contain the same linking group and / or aromatic group. Specific examples of such a reversible developer are described in, for example, JP-A-9-290563 and JP-A-11-188969.

The relationship between the color density and the temperature of the reversible thermosensitive recording medium shown in FIG. 1 is also applied to the case of the third group of the present invention. Can be. Printing with this recording layer provides high contrast and excellent image quality. In addition, it has excellent storage stability and durability against repeated printing and erasure, and is particularly suitable as the reversible thermosensitive recording medium of the present invention. Printing on a reversible recording medium using this recording layer can be performed with a thermal head in the same manner as normal thermal recording, and erasing can be performed with a temperature-controlled heat roller, a heating element such as a ceramic heater, and a thermal head. It can be used with a small and simple recording device.

The third group of the reversible thermosensitive recording media of the present invention also comprises
The leuco dye, the color developer and the coloring / decoloring controlling agent form a recording layer together with the resin. The resin used at this time only needs to be able to bind these materials on the support, and conventionally known resins are widely used. Above all, in order to improve the durability at the time of repetition, a resin curable by heat, ultraviolet rays, electron beams, or the like is preferably used, and a thermosetting resin using an isocyanate compound or the like as a crosslinking agent is particularly preferably used. .

In the third group of the present invention, an under layer, a protective layer, a back layer, and the like may be provided in order to improve color sensitivity, durability, and light resistance. In the layer, together with the resin, an organic / inorganic filler, an ultraviolet absorber, a lubricant, a coloring pigment, and the like can be used. In particular, it has excellent durability.

As the support of the third group of the reversible thermosensitive recording medium of the present invention, it is sufficient that the recording layer can be retained, and preferably, paper, synthetic paper, PET film or the like is used. Further, the support may be attached to another material via these supports.

The third group of the reversible thermosensitive recording medium of the present invention comprises:
By providing both the thermoreversible recording section and the information recording section, the information stored in the information storage section can be displayed on the thermoreversible recording section so that the information can be confirmed without a special device. , Convenience is improved. As the storage unit used at that time, a magnetic recording layer, a magnetic stripe, an IC recording unit, an optical memory, or the like is preferably used.

Further, similarly, these can be processed into a shape according to the use thereof, and may be formed into a card shape, a sheet shape,
It is processed into a roll or the like. Cards processed into prepaid cards, point cards, and credit cards, etc., and those processed into sheets are printed when processed into general document size such as A4 size. By using the / erase device, it can be widely used not only for trial printing, but also for temporary output such as circular documents and conference materials. Furthermore, the material processed into a roll shape can be used for a display board, a bulletin board, or an electronic blackboard, for example, by being incorporated in a device having a printing / erasing unit. Since such a display device does not generate dust and dirt, it can be preferably used in a clean room or the like.

[0069]

The present invention will be described in more detail with reference to the following examples. In the examples, “parts” and “%” are based on weight. [First Group of the Invention] Example 1 [Preparation of Recording Layer] 4 parts of a developer having the following structure

[0070]

Embedded image Acrylic polyol 50% solution (Mitsubishi Rayon, LR503) 9 parts Methyl ethyl ketone 70 parts

The above composition was pulverized and dispersed to an average particle size of 1 μm using a ball mill. 10 parts of Coronate HL (a 75% solution of adduct-type hexamethylene diisocyanate in ethyl acetate) manufactured by Nippon Polyurethane Co., Ltd.
One part of 2-anilino-3-methyl-6-dibutylaminofluoran was added and stirred well to prepare a recording layer coating solution.
The recording layer coating solution having the above composition was applied on a 188 μm-thick polyester film using a wire bar.
After drying at 2 ° C. for 2 minutes and then at 60 ° C. for 24 hours, a recording layer having a thickness of about 8.0 μm was provided to form a recording layer.

[Preparation of Protective Layer] UV-absorbing polymer 40% solution (UV-G100, manufactured by Nippon Shokubai Co., Ltd.) 10 parts Alumina (AL-150SG, manufactured by Showa Denko KK) 2.5 parts Silicon graft polymer (Nippon Oil & Fats Co., Ltd.) 0.2 parts Methyl ethyl ketone 10 parts

The above composition was pulverized and dispersed using a ball mill to an average particle size of about 0.8 μm. To the resulting dispersion was added 1 part of Coronate HL manufactured by Nippon Polyurethane Co., Ltd., and the mixture was stirred well to prepare a protective layer coating solution. The protective layer coating solution is coated on the recording layer using a wire bar,
After drying for 20 minutes, the resultant was heated at 60 ° C. for 24 hours to provide a recording layer having a thickness of about 3.0 μm, thereby producing a reversible recording medium of the present invention.

Example 2 A reversible recording medium was produced in the same manner as in Example 1 except that the coating solution for the protective layer in Example 1 was changed as follows. UV absorbing polymer 40% solution (Nippon Shokubai Co., Ltd., UV-G100) 10 parts Silica (Mizusawa Chemical Co., Ltd., P-832) 2 parts Silicon graft polymer (Nippon Oil & Fat Co., Ltd., FS700) 0.5 parts Methyl ethyl ketone 10 parts The above composition was prepared using a ball mill to give an average particle size of about 1.0 μm.
m, and 1 part of Coronate HL manufactured by Nippon Polyurethane Co., Ltd. was added to the resulting dispersion, followed by thorough stirring to prepare a protective layer coating solution.

Example 3 A reversible recording medium was produced in the same manner as in Example 1 except that the coating solution for the protective layer in Example 1 was changed as follows. 40% UV absorbing polymer solution (UV-A11, manufactured by Nippon Shokubai Co., Ltd.) 10 parts Silica (P-832, manufactured by Mizusawa Chemical Company) 2.5 parts Silicon graft polymer (FS700, manufactured by NOF Corporation) 1 part Methyl ethyl ketone 10 parts The above composition was prepared by using a ball mill to obtain an average particle size of about 1.5 μm.
m, and 1 part of Coronate HL manufactured by Nippon Polyurethane Co., Ltd. was added to the resulting dispersion, followed by thorough stirring to prepare a protective layer coating solution.

Comparative Example 1 The composition of the protective layer solution of Example 1 was changed as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1. 40% UV-absorbing polymer solution (PUVA30S, non-crosslinked type, manufactured by Otsuka Chemical Co.) Styrene copolymer (copolymerization ratio 30:70, average molecular weight about 10,000) 10 parts Silicon oil 1.5 parts Methyl ethyl ketone 7 parts Above The composition was stirred well to prepare a protective layer coating solution.

Comparative Example 2 The composition of the protective layer solution of Example 1 was changed as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 1. Acrylic polyol 40% solution (Mitsubishi Rayon Co., LR503) 12 parts Isocyanate (Nippon Polyurethane Co., Coronate HL) 2 parts Low molecular ultraviolet absorber (Sumitomo Chemical Co., Ltd., SUMISORB 310) 0.8 parts Silicone oil 1 part Methyl ethyl ketone 10 parts The above composition was well stirred to prepare a protective layer coating solution.

<Measurement of Glossiness> The glossiness of the reversible thermosensitive recording medium was measured with a variable-angle glossiness meter (manufactured by Nippon Denshoku Industries Co., Ltd.).

<Test 1> Surface of recording medium after repeated erasure printing The surface of the recording medium after erasure and printing were repeated 50 times using a card printer (R3000) manufactured by Kyushu Matsushita was visually evaluated. The evaluation was performed by assigning the following four ranks. 1: No dents and scratches occurred on the surface of the recording medium. 2: No dents were formed on the surface of the recording medium, but scratches were generated. 3: A dent and a scratch occurred on the surface of the recording medium. 4: Severe dents and scratches occurred on the surface of the recording medium.

<Test 2> Change in color density after repeated erasure printing Erasure and printing were repeated 50 times using a card printer (R3000). 1: The image portion had good color development and no change in density was observed. 2: The color development in the image area was not uniform, and a decrease in density was also observed. 3: The coloring state of the image area was extremely poor, and the density was significantly reduced.

<Test 3> Light fastness First and 50th tests using a card printer (R3000)
The printed portion after erasure printing is repeated for 5 hours and then left under irradiation for 5500 Lux for 100 hours. After that, the printing portion is entirely erased by a card printer (R3000). The unerased residue at that time was measured with a Macbeth densitometer RD914, and the light resistance was evaluated based on the difference in the change according to the following equation.

[0082]

## EQU1 ## Change in remaining erased density after light irradiation = (density after erasure after light fastness test)-(background density after light fastness test)

[0083]

[Table 1]

In Examples 1 to 3, there were no dents or changes in color density after repetition, and there was no coloring due to light irradiation. In Comparative Examples 1 and 2, the initial light fastness was good. However, dents at the time of repetition, a decrease in color density, and light resistance were poor. In particular, in Comparative Example 2, it is considered that the difference in light fastness between the initial stage and the repeated stage is due to the precipitation and diffusion of the ultraviolet absorber.

[Second Group of the Invention] Example 4 [Preparation of Recording Layer] 4 parts of a developer having the following structure

[0086]

Embedded image Acrylic polyol 50% solution (Mitsubishi Rayon Co., Ltd., LR503) 9 parts Methyl ethyl ketone 75 parts

The above composition was pulverized and dispersed to an average particle size of 1 μm using a ball mill. 10 parts of Coronate HL (a 75% solution of adduct-type hexamethylene diisocyanate in ethyl acetate) manufactured by Nippon Polyurethane Co., Ltd.
One part of 2-anilino-3-methyl-6-dibutylaminofluoran was added and stirred well to prepare a recording layer coating solution.
The recording layer coating solution having the above composition was applied on a 188 μm-thick polyester film using a wire bar.
After drying at 2 ° C. for 2 minutes and then at 60 ° C. for 24 hours, a recording layer having a thickness of about 8.0 μm was provided to form a recording layer.

[Preparation of Protective Layer] UV-absorbing polymer 40% solution (Nippon Shokubai Co., Ltd., UV-G100) 10 parts Filler (Toshiba Silicone Co., Ltd., Tospearl 103) 2.5 parts Silicon graft polymer (Toagosei Co., Ltd.) , Reseda GS-1015) 0.5 part Methyl ethyl ketone 5 parts Isocyanate (Nippon Polyurethane Co., Ltd., Coronate HL) 1 part The above composition was stirred well to prepare a protective layer coating solution.

A protective layer coating solution having the above composition was applied on the recording layer using a wire bar, dried at 100 ° C. for 2 minutes, and dried at 60 ° C. for 24 hours to form a protective layer having a thickness of about 3 μm. A reversible thermosensitive recording medium of the present invention was prepared. The coefficient of dynamic friction of the surface was 0.18.

Example 5 The composition of the protective layer solution of Example 4 was changed as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 4.
The coefficient of kinetic friction of the surface was 0.12. UV absorbing polymer 40% solution (Nippon Shokubai Co., Ltd., UV-A11) 10 parts Filler (Toshiba Silicone Co., Ltd., Tospearl 105) 1.5 parts Silicon graft polymer (Toagosei Co., Ltd., Reseda GS-1015) 0.5 Part: methyl ethyl ketone: 5 parts: isocyanate (manufactured by Nippon Polyurethane Co., Coronate HL): 1 part The above composition was stirred well to prepare a protective layer coating solution.

Example 6 Except that the composition of the protective layer solution of Example 4 was as follows:
A reversible thermosensitive recording medium was prepared in the same manner as in Example 4.
The coefficient of dynamic friction of the surface was 0.16. 40% UV absorbing polymer solution (Nippon Shokubai Co., Ltd., UV-G100) 10 parts Filler (Toshiba Silicone Co., Ltd., Tospearl 103) 1 part Silicon graft polymer (Shin-Etsu Chemical Co., Ltd., X-22-8004) 3 parts Methyl ethyl ketone 5 Part Isocyanate (Coronate HL, manufactured by Nippon Polyurethane Co., Ltd.) 1 part The above composition was stirred well to prepare a coating solution for the protective layer.

Comparative Example 3 The composition of the protective layer liquid of Example 4 was changed as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 4.
The coefficient of dynamic friction of the surface was 0.30. 40% UV-absorbing polymer solution (PUVA30S, non-crosslinked type, manufactured by Otsuka Chemical Co.) Styrene copolymer (copolymerization ratio: 30:70, average molecular weight: about 10,000) 10 parts Filler (Tospearl 130, manufactured by Toshiba Silicone Co., Ltd.) 2 parts Silicon oil 0.5 parts Methyl ethyl ketone 5 parts The above composition was stirred well to prepare a protective layer coating solution.

Comparative Example 4 The composition of the protective layer liquid of Example 4 was changed as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 4.
The coefficient of dynamic friction of the surface was 0.25. Acrylic polyol 40% solution (Mitsubishi Rayon Co., LR503) 12 parts Isocyanate (Nippon Polyurethane Co., Coronate HL) 2 parts Low molecular ultraviolet absorber (Sumitomo Chemical Co., Ltd., SUMISORB 310) 0.8 parts Silicone oil 1 part Methyl ethyl ketone 10 parts The above composition was well stirred to prepare a protective layer coating solution.

<Test 4> Surface of Recording Medium after Repeated Erasing and Printing The surface of the recording medium after erasing and printing were repeated 50 times using a card printer (R3000) manufactured by Kyushu Matsushita Corporation was visually evaluated. The evaluation was performed by assigning the following four ranks. 1: No dents and scratches occurred on the surface of the recording medium. 2: No dents were formed on the surface of the recording medium, but scratches were generated. 3: A dent and a scratch occurred on the surface of the recording medium. 4: Severe dents and scratches occurred on the surface of the recording medium.

<Test 5> Change in color density after repeated erasure printing Erasure and printing were repeated 50 times using a card printer (R3000), and changes in color density were visually observed and evaluated according to the following ranks. 1: The image portion had good color development and no change in density was observed. 2: The color development in the image area was not uniform, and a decrease in density was also observed. 3: The coloring state of the image area was extremely poor, and the density was significantly reduced.

<Test 6> Light fastness First and 50th tests using a card printer (R3000)
The printed portion after erasure printing is repeated for 5 hours and then left under irradiation for 5500 Lux for 100 hours. After that, the printing portion is entirely erased by a card printer (R3000). The unerased residue at that time was measured with a Macbeth densitometer RD914, and the light resistance was evaluated based on the difference in the change according to the following equation.

[0097]

## EQU2 ## Change in remaining erased density after light irradiation = (density after erasure after light fastness test)-(background density after light fastness test)

[0098]

[Table 2]

In Examples 4 to 6, there was no dent or change in color density after repetition, and there was no coloring due to light irradiation. In Comparative Examples 3 and 4, the initial light resistance was good. However, dents at the time of repetition, a decrease in color density, and light resistance were poor. In particular, in Comparative Example 4, regarding light resistance,
It is considered that the large difference between the initial stage and the repeated stage is due to the precipitation and diffusion of the ultraviolet absorber.

[Third Group of the Invention] Example 7 [Formation of Recording Layer] 4 parts of a developer having the following structure

[0101]

Embedded image Acrylic polyol 50% solution (Mitsubishi Rayon, LR503) 9 parts Methyl ethyl ketone 70 parts

The above composition was pulverized and dispersed using a ball mill to an average particle size of 1 μm. 10 parts of Coronate HL (a 75% solution of adduct-type hexamethylene diisocyanate in ethyl acetate) manufactured by Nippon Polyurethane Co., Ltd.
One part of 2-anilino-3-methyl-6-dibutylaminofluoran was added and stirred well to prepare a recording layer coating solution.
The recording layer coating solution having the above composition was applied on a 188 μm-thick polyester film using a wire bar.
After drying at 2 ° C. for 2 minutes and then at 60 ° C. for 24 hours, a recording layer having a thickness of about 8.0 μm was provided to form a recording layer.

[Preparation of Protective Layer] 10 parts of a 40% UV absorbing polymer solution (manufactured by Nippon Shokubai Co., Ltd., UV-G100, hydroxyl value: 22, Tg: 30 ° C., molecular weight of about 30,000) Filler (manufactured by Toshiba Silicone Co., Tospearl) 105) 5 parts Methyl ethyl ketone 5 parts Isocyanate (Coronate HL, manufactured by Nippon Polyurethane Co., Ltd.) 1 part The above composition was stirred well to prepare a protective layer coating solution.

A protective layer coating solution having the above composition was applied to the recording layer using a wire bar, dried at 100 ° C. for 2 minutes, and dried at 60 ° C. for 24 hours to form a protective layer having a thickness of about 3 μm. A reversible thermosensitive recording medium of the present invention was prepared.

Example 8 Except that the composition of the protective layer solution of Example 7 was as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 7. 40% UV absorbing polymer solution 10 parts (Nippon Shokubai Co., Ltd., UV-G7, hydroxyl value: 20, Tg: 70 ° C., molecular weight about 80,000) Filler (Toshiba Silicone Co., Ltd., Tospearl 105) 5 parts Methyl ethyl ketone 5 parts Isocyanate ( 1 part of Nippon Polyurethane Co., Ltd., Coronate HL) 1 part The above composition was stirred well to prepare a coating solution for the protective layer.

Example 9 Except that the composition of the protective layer solution of Example 7 was as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 7. UV absorbing polymer 40% solution 10 parts (Nippon Shokubai Co., Ltd., UV-A11, hydroxyl value: 39, Tg: 70 ° C., molecular weight about 30,000) Filler ( Tospearl 105 manufactured by Toshiba Silicone Co., Ltd. 5 parts Methyl ethyl ketone 5 parts Isocyanate (manufactured by Nippon Polyurethane Co., Ltd., Coronate HL) 1 part The above composition was stirred well to prepare a coating solution for a protective layer.

Example 10 Except that the composition of the protective layer liquid of Example 7 was as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 7. 8 parts of a 30% UV-absorbing polymer solution (manufactured by YAS & Co., XL-115, hydroxyl value: 50, Tg: 70 ° C, molecular weight: about 20,000, UV light) Filler (Toshiba Silicone Co., Ltd., Tospearl 105) 5 parts Methyl ethyl ketone 5 parts Isocyanate (Nippon Polyurethane Co., Coronate HL) 1 part The above composition is stirred well to prepare a coating solution for the protective layer. did.

Comparative Example 5 The composition of the protective layer solution of Example 7 was changed as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 7. 40% UV absorbing polymer solution (PUVA30S, non-crosslinked type, manufactured by Otsuka Chemical Co.) Styrene copolymer (copolymerization ratio: 30:70, average molecular weight: about 10,000) 10 parts Filler (manufactured by Toshiba Silicone Co., Tospearl 130) 2 parts Silicon oil 0.5 parts Methyl ethyl ketone 5 parts The above composition was stirred well to prepare a protective layer coating solution.

Comparative Example 6 The composition of the protective layer liquid of Example 7 was changed as follows,
A reversible thermosensitive recording medium was prepared in the same manner as in Example 7. Acrylic polyol 40% solution 12 parts (Mitsubishi Rayon Co., Ltd., LR503) Isocyanate (Nihon Polyurethane Co., Ltd., Coronate HL) 2 parts Low molecular ultraviolet absorber 0.8 part (Sumitomo Chemical Co., Ltd., SUMISORB 310) Silicon oil 1 part Methyl ethyl ketone 10 parts The above composition was well stirred to prepare a protective layer coating solution.

<Test 7> Surface of recording medium after repeated erasure printing The surface of the recording medium after erasure and printing were repeated 50 times using a card printer (R3000) manufactured by Kyushu Matsushita was visually evaluated. The evaluation was performed by assigning the following four ranks. 1: No dents and scratches occurred on the surface of the recording medium. 2: No dents were formed on the surface of the recording medium, but scratches were generated. 3: A dent and a scratch occurred on the surface of the recording medium. 4: Severe dents and scratches occurred on the surface of the recording medium.

<Test 8> Change in color density after repeated erasure printing Erasure and printing were repeated 50 times using a card printer (R3000), and changes in color density were visually observed and evaluated according to the following ranks. 1: The image portion had good color development and no change in density was observed. 2: The color development in the image area was not uniform, and a decrease in density was also observed. 3: The coloring state of the image area was extremely poor, and the density was significantly reduced.

<Test 9> Light fastness First and 50th tests using a card printer (R3000)
The printed portion after erasure printing is repeated for 5 hours and then left under irradiation for 5500 Lux for 100 hours. After that, the printing portion is entirely erased by a card printer (R3000). The unerased residue at that time was measured with a Macbeth densitometer RD914, and the light resistance was evaluated based on the difference in the change according to the following equation.

[0113]

## EQU3 ## Change in remaining erase density after light irradiation = (density after erasure after light fastness test)-(background density after light fastness test)

[0114]

[Table 3]

In Examples 7 to 10, there was no dent or change in color density after repetition, and there was no coloring due to light irradiation. In Comparative Examples 5 and 6, the initial light resistance was good. However, dents at the time of repetition, decrease in color density,
Lightfastness was poor. In particular, in Comparative Example 6, the difference in light resistance between the initial stage and the repeated stage is considered to be due to the precipitation and diffusion of the ultraviolet absorber.

[0116]

As apparent from the detailed and specific explanations above, all of the reversible thermosensitive recording media of the present invention are excellent in light resistance and do not cause dents on the recording medium even after repeated use. It has excellent durability.

[Brief description of the drawings]

FIG. 1 is a diagram showing color development / decoloration characteristics of a reversible thermosensitive recording medium of the present invention.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B41M 5/18 101D (72) Inventor Hiromi Furuya 1-3-6 Nakamagome 1-chome, Ota-ku, Tokyo Ricoh Company, Ltd. (72) Inventor Kyoji Tsutsui 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Company Limited (reference) 2H026 AA07 AA09 BB01 DD12 DD15 DD32 DD48 DD55

Claims (19)

[Claims] 1. A reversible thermosensitive composition using an electron-donating color-forming compound and an electron-accepting compound on a support and capable of forming a relatively colored state by heating and / or a difference in cooling rate after heating. Reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a substance, having a protective layer containing a UV-absorbing polymer in a cross-linked state, and having a surface gloss of 40
% Of the thermoreversible recording medium. 2. The reversible thermosensitive recording medium according to claim 1, wherein the protective layer contains an organic and / or inorganic filler. 3. The reversible thermosensitive recording medium according to claim 2, wherein the content of the filler is 5 to 50 in terms of a solid content relative to 100 parts by weight of the protective layer resin. 4. The reversible thermosensitive recording medium according to claim 2, wherein the filler is coated with calcium. 5. A reversible thermosensitive composition which can form a relatively colored state by using an electron-donating color-forming compound and an electron-accepting compound on a support and heating and / or a cooling rate after heating. Reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a substance, having a protective layer containing a UV-absorbing polymer in a cross-linked state, and having a surface friction coefficient of 0.2 or less. Reversible thermosensitive recording medium. 6. The reversible thermosensitive recording medium according to claim 5, wherein the protective layer contains a silicon graft polymer. 7. The reversible thermosensitive recording medium according to claim 6, wherein the silicon graft polymer is in a cross-linked state. 8. The reversible thermosensitive recording medium according to claim 5, wherein the ultraviolet absorbing polymer and / or the silicon graft polymer are cross-linked by isocyanate. 9. The reversible thermosensitive recording medium according to claim 5, wherein the ultraviolet absorbing polymer is contained in a protective layer. 10. A reversible thermosensitive composition capable of forming a relatively colored state by using an electron-donating color-forming compound and an electron-accepting compound on a support and heating and / or a cooling rate after heating. Reversible thermosensitive recording medium having a reversible thermosensitive recording layer containing a substance, comprising a UV-absorbing polymer having a hydroxyl value of 20 or more, wherein the polymer is in a cross-linked state. . 11. The reversible thermosensitive recording medium according to claim 10, further comprising a protective layer on the reversible thermosensitive recording layer, wherein the polymer is contained in the protective layer. 12. The ultraviolet absorbing polymer having a Tg of 50.
The reversible thermosensitive recording medium according to claim 10 or 11, wherein the temperature is at least ° C. 13. The reversible thermosensitive recording medium according to claim 10, wherein the content of the ultraviolet absorbing component of the ultraviolet absorbing polymer is 50% or more. 14. The ultraviolet absorbing polymer according to claim 1, wherein the weight average molecular weight is 10,000 or more.
14. The reversible thermosensitive recording medium according to any one of 0 to 13. 15. The reversible thermosensitive recording medium according to claim 10, wherein the ultraviolet absorbing component of the ultraviolet absorbing polymer has a benzotriazole skeleton. 16. The reversible thermosensitive recording medium according to claim 10, wherein the ultraviolet absorbing polymer is in a cross-linked state by an isocyanate compound. 17. The reversible thermosensitive recording medium according to claim 16, wherein the isocyanate compound is an adduct type, a burette type, or a trimer type of hexamethylene diisocyanate. 18. The reversible thermosensitive recording medium according to claim 1, further comprising a thermoreversible recording section and an information storage section. 19. The reversible thermosensitive recording medium according to claim 18, wherein the information storage section is at least one of a magnetic recording layer, a magnetic stripe, an IC memory, and an optical memory.