JPH0811440A - Reversible thermosensitive recording medium - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a reversible thermosensitive recording medium which is free from deterioration of an image and deterioration of transparency of a transparent portion even when an image is repeatedly formed and erased by a heating body such as a thermal head. [Structure] A heat-sensitive recording layer whose transparency reversibly changes depending on temperature is provided on a support, and a silicon-containing iminohydantoin-based heavy chain having a repeating unit represented by the following general formula (1) is further provided thereon. A reversible thermosensitive recording medium having an overcoat layer formed of a united body. Embedded image

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversible thermosensitive recording medium for recording and erasing by utilizing the reversible change in transparency of the thermosensitive medium with temperature.

[0002]

2. Description of the Related Art As a recording medium capable of reversible recording and erasing, JP-A-54-119377 and 55-
Japanese Patent No. 154198 discloses that a thermosensitive recording layer in which a low molecular organic compound such as higher alcohol or higher fatty acid is dispersed in a resin matrix such as polyester is provided on a support. The transparency of the thermosensitive recording layer changes depending on the temperature, and recording and erasing are possible. However, in conventional reversible thermosensitive recording media, when an image is formed by heating with a heating body such as a thermal head, the surface is easily deformed by the heat and pressure of these heating bodies, and therefore image formation and erasing are repeated. There is a problem that the amount of deformation increases and the transparency of the portion that should be transparent decreases.
In order to solve this problem, JP-A-63-221087
In the publication, there is proposed a method of providing an overcoat layer of silicone resin, silicone rubber or the like to reduce the friction coefficient of the surface. However, since this overcoat layer has insufficient adhesion to the heat-sensitive recording layer, there is a problem that the image is deteriorated due to peeling due to repeated mechanical action.

[0003]

SUMMARY OF THE INVENTION The present invention provides a reversible thermosensitive recording medium which is free from deterioration of the image and deterioration of the transparency of the transparent portion even when the image forming and erasing are repeatedly performed by a heating body such as a thermal head. With the goal.

[0004]

The present invention has found that the above object can be achieved by providing an overcoat layer composed of an iminohydantoin-based polymer containing silicon on a heat-sensitive recording layer. That is, according to the present invention,
A reversible thermosensitive recording medium comprising, on a support, a thermosensitive recording layer having a resin matrix and a low-molecular organic compound dispersed in the resin matrix as a main component, and the transparency of which reversibly changes depending on temperature changes. There is provided a reversible thermosensitive recording medium characterized in that an overcoat layer comprising an iminohydantoin-based polymer containing silicon is provided on the thermosensitive recording layer. Further, according to the present invention, the reversible thermosensitive recording medium, wherein the silicon-containing iminohydantoin-based polymer is a copolymer having a repeating unit represented by the following general formula (1). Will be provided.

Embedded image (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom or a CN group, a phenyl group, or an alkyl group having 1 to 4 carbon atoms. Or a phenyl group substituted with an alkoxy group or a halogen atom, which may be the same or different.
Has the formula _{-Ph-D-C (L 1} ) (L 2) -C (L 3)
Represents a divalent linking group represented by (L ₄ )-or Ph-D-, and in this formula, L ₁ , L ₂ , L ₃ and L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. And may be the same or different, D is a bond or -E-
(CH ₂ ) m- (where m represents an integer of 1 to 6),
_{-E-Si (CH 3) 2} -, - E-Si (CH 3) (P
h)-and -E-Si (Ph) _2- representing a divalent bonding group, wherein E is a bond or -O-, -S.
_{-, - O-CH 2 -} , - O-CO- and -NH-CO-
Ph which is a divalent linking group selected from
Is bound to the nitrogen atom of the hydantoin ring. B represents a divalent linking group having 2 or more carbon atoms. n, y and z are 1
Represents the above integers. According to the present invention, the reversible thermosensitive recording medium is characterized in that the silicon-containing iminohydantoin-based polymer is a copolymer having a repeating unit represented by the following general formula (2). Will be provided.

Embedded image (Wherein R ₁ , R ₂ , R ₃ , R ₄ ... Rx + ₁ , Rx + ₂ and Rx +
₃ represents a halogen atom or an alkyl group having 1 to 12 carbon atoms which may be substituted with a CN group, a phenyl group, an alkyl group or an alkoxy group having 1 to 4 carbon atoms, or a phenyl group substituted with a halogen atom. , May be the same or different. A has the formula _{-Ph-D-C (L 1} )
It represents a divalent linking group represented by (L ₂ ) -C (L ₃ ) (L ₄ )-or Ph-D-, and in this formula, L ₁ , L ₂ , L ₃
And L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and may be the same or different, and D is a bond or —E— (CH ₂ ) — (where m is 1 to 1). 6
An integer of), - E-Si (CH 3) 2 -, - E-Si
Represents a divalent linking group selected from (CH ₃ ) (Ph)-and -E-Si (Ph) _2- , wherein E is a bond or-
O -, - S -, - O-CH 2 -, - O-CO- , and -N
It represents a divalent linking group selected from H-CO-, and Ph contained in A is bound to the nitrogen atom of the hydantoin ring. B represents a divalent linking group having 2 or more carbon atoms. n ₁ ,
n ₂ , ... Np, y and z represent an integer of 1 or more, and x is 3
The above integers are represented, and p represents an integer of 2 or more. According to the present invention, the reversible thermosensitive material is characterized in that the silicon-containing iminohydantoin-based polymer is a multi-block copolymer having a repeating unit represented by the following general formula (3). A recording medium is provided.

Embedded image (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom or a CN group, a phenyl group, or an alkyl group having 1 to 4 carbon atoms. Or a phenyl group substituted with an alkoxy group or a halogen atom, which may be the same or different.
Has the formula _{-Ph-D-C (L 1} ) (L 2) -C (L 3)
(L ₄ )-or Ph-D- represents a divalent linking group, and in this formula, L ₁ , L ₂ , L ₃ and L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. And may be the same or different, D is a bond or -E-
(CH ₂ ) m- (where m represents an integer of 1 to 6),
_{-E-Si (CH 3) 2} -, - E-Si (CH 3) (P
h)-and -E-Si (Ph) _2- , which represents a divalent linking group, wherein E is a bond or -O-, -S.
_{-, - O-CH 2 -} , - O-CO- and -NH-CO-
A divalent linking group selected from
Is bound to the nitrogen atom of the hydantoin ring. B ₁ , B ₂
Bq represents a divalent linking group having 2 or more carbon atoms. n, y and z ₁ , z ₂ ... Zq represent an integer of 1 or more, and q represents an integer of 2 or more. According to the present invention, the reversible thermosensitive material is characterized in that the silicon-containing iminohydantoin-based polymer is a multi-block copolymer having a repeating unit represented by the following general formula (4). A recording medium is provided.

[Chemical 4] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ ... Rx, Rx + ₁ , Rx + ₂ and Rx + ₃ are an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom or a CN group, or A phenyl group, or an alkyl group or an alkoxy group having 1 to 4 carbon atoms or a phenyl group substituted with a halogen atom, which may be the same or different, and A is of the formula -Ph-D-C.
(L ₁ ) (L ₂ ) —C (L ₃ ) (L ₄ ) — or Ph-D— represents a divalent linking group, and in this formula L ₁ ,
L ₂ , L ₃ and L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and may be the same or different, and D is a bond or —E— (CH ₂ ) m- (. However, m is an integer of 1~6), - E-Si ( CH 3) 2
-, - E-Si (CH 3) (Ph) - and -E-Si
Represents a divalent linking group selected from (Ph) ₂
Is a bond or —O—, —S—, —O—CH ₂ —, —
It represents a divalent linking group selected from O—CO— and —NH—CO—, and Ph contained in A is bound to the nitrogen atom of the hydantoin ring. B ₁ , B ₂ ... Bq represent a divalent bonding group having 2 or more carbon atoms. n ₁ , n ₂ , ... Np, y, z ₁ , z ₂
... zq represents an integer of 1 or more, x represents an integer of 3 or more, and p and q represent integers of 2 or more. According to the invention, the silicon-containing iminohydantoin-based polymer is 50% when formed into a film.
There is provided the reversible thermosensitive recording medium having the above elongation at break. Further, according to the present invention, the iminohydantoin-based polymer containing silicon is
There is provided the reversible thermosensitive recording medium having a glass transition point of 00 ° C. or higher. Furthermore, according to the present invention, there is provided the reversible thermosensitive recording medium, wherein the silicon-containing iminohydantoin-based polymer has a dynamic friction coefficient of 0.20 or less.

The reversible thermosensitive recording medium of the present invention utilizes the change from the transparent state to the cloudy opaque state and the change from the cloudy opaque state to the transparent state due to the temperature dependence of the transparency of the thermosensitive recording layer, respectively. It can be recorded and erased. The difference between the transparent state and the cloudy opaque state is presumed as follows. That is, (i) in the transparent state, the low-molecular weight organic compound particles dispersed in the resin base material are present as relatively large particles, and the light incident from one side is transmitted without being scattered to the other side, and thus is transparent. In addition, (ii) in the cloudy state, the low-molecular weight organic compound particles are composed of polycrystals of fine crystals, and the crystal axes of each are in various directions, so the light incident from one side is of low molecular weight. It is derived from the fact that the organic compound particles are refracted many times at the crystal interface and appear white because they are scattered.

In FIG. 1 (change in transparency due to heat),
The heat-sensitive layer mainly composed of the particle base material and the low molecular weight organic compound dispersed therein is in a cloudy and opaque state at a temperature of T ₀ or lower, for example. When it is heated to a temperature T _2, it becomes transparent, and even if it is returned to normal temperature below T _0, it remains transparent. It is considered that this is because the low-molecular weight organic compound is in a semi-molten state from the temperature T ₂ to T ₀ or lower and the crystal grows from a polycrystal to a single crystal. Further heating to a temperature of T ₃ or higher brings about an intermediate state between the maximum transparent state and the maximum opaque state. Next, when the temperature is lowered from this state,
It returns to the initial cloudy opaque state without becoming transparent.
It is considered that this is because the low-molecular weight organic compound is melted at a temperature of T ₃ or higher and then cooled to be cooled, whereby a polycrystal is deposited. The opaque state is heated to a temperature of T _{1 to} T ₂ , and then cooled to room temperature, that is, a temperature equal to or lower than T _0, to be in an intermediate state between transparent and opaque. Further Returning to room temperature after heating what became transparent at the room temperature to again T ₃ or more temperature returns to cloudy opaque state again. That is, it can be in an opaque or transparent state and an intermediate state at room temperature. Therefore, by selectively applying heat, the heat-sensitive layer can selectively form a cloudy image on a transparent background and a transparent image on a cloudy background, and the change can be repeated many times.

The present invention will be described in more detail below. As described above, the reversible thermosensitive recording medium of the present invention is characterized in that an overcoat layer made of an iminohydantoin-based polymer containing silicon is provided on the upper surface of the reversible recording layer. As the iminohydantoin-based polymer containing silicon used in the present invention, particularly in terms of preventing a decrease in transparency due to repeated image formation and erasing 100 times or more,
A silicon-containing iminohydantoin copolymer having repeating units represented by the following general formulas (1) and (2), or an imino containing silicon having repeating units represented by the following general formulas (3) and (4) Hydantoin multiblock copolymers are preferred.

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[Chemical 4]

In the above general formulas (1) to (4),
R ₁ , R ₂ , R ₃ , R ₄ , ... Rx + ₁ , Rx + ₂ and Rx + ₃ are
The substituents may be the same or different and are selected from the groups shown below. (A) A linear or branched alkyl group having 1 to 12 carbon atoms. (B) A straight-chain or branched alkyl group having 1 to 12 carbon atoms, which is substituted with one or more halogen atoms or CN group. In this case, the halogen atom includes Cl, Br, F and the like. (C) Phenyl group. (D) A phenyl group substituted with an alkyl group or an alkoxy group having 1 to 4 carbon atoms or a halogen atom.

In the copolymer having the repeating units represented by the above general formulas (1) to (4), A is represented by the formula-
_{Ph-D-C (L 1} ) (L 2) -C (L 3) (L 4) - or shows a -Ph-D-. L ₁ , which constitutes A,
L ₂ , L ₃ and L ₄ are the same or different substituents and represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Also, the D constituting the A bond or -E- (CH ₂₎ m- (provided that, m is an integer of 1~6), - E-Si ( CH 3) 2 -, - E- Si (CH ₃ )
It represents a divalent linking group selected from (Ph)-and -E-Si (Ph) _2- . The benzene ring Ph contained in A is bonded to the nitrogen atom of iminohydantoin and is bonded to D at the p-position thereof, and the above E constituting A is —O—CH ₂ —, —O—CO—. Or -NH-CO-
In the case of, the heteroatom is always bound to the benzene ring.
Further, Ph represents a phenyl group and -Ph- represents a phenylene group.

In the general formulas (1) to (4), B ₁ , B ₂ , ... Bq represent a divalent linking group having 2 or more carbon atoms. This bonding group has a divalent aliphatic group having 2 to 32 carbon atoms which may have a substituent, and a carbon number 2 to 32 which has a hetero atom in the carbon chain and may have a substituent.
2 divalent aliphatic groups, which may have a substituent, carbon number 2
To a divalent alicyclic group having 32 to 32, a divalent aromatic group having a carbon number of 2 to 32, which may have a substituent, a divalent polycyclic aromatic group,
It may have a substituent-(CH ₂ ) f-Ph- (C
H ₂₎ g-, which may have a substituent machine - (CH ₂₎ t-P
h-, optionally having -Ph-O-Ph-,
A divalent linking group such as -Ph-Ph- which may have a substituent is included, but a divalent linking group having a benzene ring is preferable. Although there are many substituents that can be present in these divalent linking groups, halogen atoms, lower alkyl groups and alkoxy groups are preferred. Further, Ph represents a phenylene group, and f, g and t may be the same or different, and represent an integer of 1 to 16.

Further, in the above general formulas (1) to (4),
y represents the repeating number of the silicon-containing oligomer component in the repeating units constituting the silicon-containing iminohydantoin-based polymer of the present invention, and is preferably an integer of 1 to 130. n, n ₁ , n ₂ , n ₃ , ...
... np represents the repeating number of the siloxane monomer that constitutes the above-mentioned silicon-containing oligomer component, and is preferably an integer of 1 to 80. Also, np
The p contained in the above represents the number of kinds of monomers constituting the above-mentioned silicon-containing oligomer, and is preferably an integer of 1-10. x represents a number for specifying a substituent bonded to Si, and this number is an odd number and has a relationship represented by p = (x + 1) / 2 with p described above.

Furthermore, z, z ₁ , z ₂ , ... Zq represent the number of repeating monomer components containing no silicon, and are preferably integers from 1 to 250. Q contained in zq shown here is a number indicating how many kinds of components do not contain silicon, and is preferably an integer of 2 to 10.

The iminohydantoin-based polymer containing silicon, which has been described in detail above, has high heat resistance and excellent mechanical properties, and inevitably has a large molecular weight, and therefore has a general formula (1) to (4). Also the number average molecular weight of the silicon-containing iminohydantoin-based polymer having a repeating unit represented,
5,000 to 500,000, preferably 100,000
It is 0 to 500,000.

The silicon-containing iminohydantoin copolymer having the repeating unit represented by the general formula (1) is
It is produced by a method of cycloaddition-polymerizing diisocyanate containing silicon and hydrogen cyanide. As the silicon-containing diisocyanate used in this reaction, the compound of the following general formula (5) is used.

Embedded image In the general formula (5), R ₁ , R ₂ , R ₃ , R ₄ , n and A
Are the same as those described above in the explanation of the general formulas (1) to (4), and this compound is produced according to the conventional method shown in USP 4,518,758.

The diisocyanate shown below is used as the silicon-free diisocyanate that is a raw material for synthesizing the polymer having the repeating unit represented by the general formula (1). 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 1,12-diisocyanate dodecane, isophorone diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, toluene-
2,4-diisocyanate, toluene-2,6-diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, m-xylyl Diisocyanate, 4,
4'-diphenylmethane diisocyanate, 4,4'-
Diisocyanate-3,3-dimethyldiphenylmethane, 4,4′-diisocyanate diphenyl ether,
3,4'-diisocyanate diphenyl ether, 4,
4'-diisocyanate biphenyl, 4,4'-diisocyanate-3,3'-dimethylbiphenyl and 3,
3'-dichlorophenyl-4,4'-diisocyanate and the like.

The cycloaddition reaction of silicon-containing diisocyanate and non-silicon-containing diisocyanate with hydrogen cyanide is carried out by using N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide as a polymerization solvent. Of a highly polar solvent of 0 to 50 ° C. at a reaction temperature of 0.5
A reaction time in minutes to 24 hours, under normal pressure, N- cyclohexyl morpholine, N, N- _{dimethylcyclohexylamine, (C 4 H 5) 2} Sn (OC 2 H 5) 2, ((C 4 H 9) 3 S
n) ₂ O, (C ₄ H ₉ ) ₄ Sn, Ph ₃ P, (C ₄ H ₉ ) ₃ P,
_{(C 8 H 17) 3 P} , (CH 3) 3 Pb (OCOCH 3),
It can be obtained by reacting in the presence of a catalyst such as (C ₄ H ₉ ) Pb (imidazole), NaCN and triethylamine. This cyclization reaction is a known reaction for synthesizing iminohydantoins from diisocyanate and hydrogen cyanide (Reference: Poly. Reprants., 12, 162 (19).
71), 20, 183 (1979)). Further, the silicon-free diisocyanate used when synthesizing the polymer having the repeating unit represented by the general formula (1) is a single product, and the mixing ratio thereof is y and z represented by the general formula (1). Determined by

The method for producing the silicon-containing iminohydantoin copolymer having the repeating unit represented by the general formula (2) is generally carried out except that the silicon-containing diisocyanate used as a raw material is the compound of the following general formula (6). This is the same as the method for synthesizing a polymer having a repeating unit represented by the formula (1).

[Chemical 6] In the general formula (6), R ₁ , R ₂ , R ₃ , R ₄ ... Rx,
Rx + ₁ , Rx + ₂ , Rx + ₃ , n ₁ , n ₂ , ... Np, x and p
Is the same as that described in the description of the general formulas (1) to (4), and A is the same as that described in the description of the general formula (5). In addition, this compound can be produced in the same manner as the compound of the general formula (5).

The method for producing the silicon-containing iminohydantoin multiblock copolymer having the repeating units represented by the general formulas (3) and (4) is the same as the repeating units represented by the general formulas (1) and (2). Similar to the method for producing a polymer having the same, but for producing a polymer having a repeating unit represented by the general formula (3), the silicon-containing diisocyanate represented by the general formula (5) is used. The silicon-containing diisocyanate represented by the general formula (6) is used to produce a polymer having a repeating unit represented by the formula (1), and two or more kinds of the above-mentioned silicon-free diisocyanates are used as raw materials. Is added to produce a cycloaddition polymer. The conditions for the cycloaddition polymerization in this case are almost the same for both the polymers having the repeating units represented by the general formulas (3) and (4). The general formulas (3) and (4)
In the production of the multi-block polymer having the repeating unit represented by, the number of types of the silicon-free diisocyanate used in two or more types is determined by q shown in the general formulas (3) and (4).

The silicon-containing iminohydantoin-based polymer used in the overcoat layer of the present invention is different in the type of silicon-free diisocyanate used as a raw material, or is a mixture of a silicon-containing diisocyanate and a silicon-free diisocyanate. By changing the ratio, some of the performance of the resulting copolymer can be changed. For example, it is desirable to use a copolymer having a glass transition point of 200 ° C. or higher in order to prevent a decrease in transparency due to repeated image formation and erasure of 300 times or more. One or more kinds of diisocyanates are used, and the amount used is at least 25 mol% or more.

M-Phenylene diisocyanate, toluene-2,4-diisocyanate, toluene-2.6-diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy- 1,3-phenylene diisocyanate, m-xylylene diisocyanate 4,4′-diphenylmethane diisocyanate, 4,
4'-diisocyanate diphenyl ether, 4,4 '
-Diisocyanate biphenyl, 4,4'-diisocyanate-3,3'-dimethylbiphenyl, 3,3'-dichlorodiphenyl-4,4'-diisocyanate and the like.

Further, the overcoat layer may be scraped by the frictional force with the thermal head, so that the composition of the overcoat layer is fused or adhered to the heat generating portion of the thermal head or in the vicinity thereof, so that the image quality is deteriorated. Or, the phenomenon that the erasure is not performed completely occurs. In order to suppress this phenomenon, it is desirable to use a copolymer having a breaking elongation of 50% or more. In order to obtain a silicon-containing iminohydantoin-based copolymer having such mechanical properties, silicone is used. It is preferable to use one or more kinds of diisocyanates having a flexible linking group as shown below as diisocyanates not containing, or to use 10 mol% or more of diisocyanates containing silicon, and it is more preferable to use both in combination. .

4,4'-diphenylmethane diisocyanate, 4,4'-diisocyanate diphenyl ether, 4,4'-diisocyanate-3,3'-dimethyldiphenylmethane, 2,4,4-trimethylhexamethylene diisocyanate, 2,2,4 -Trimethylhexamethylene diisocyanate, or 1,6-diisocyanate hexane.

Further, in order to prevent a decrease in transparency due to repetition of image formation and erasing 500 times or more, it is desirable to reduce the frictional force generated between a heating element such as a thermal head and the overcoat layer. It is preferable to use a copolymer having a dynamic friction coefficient of 0.20 or less. In order to obtain a copolymer having such a dynamic friction coefficient, n or n ₁ + n _{2 in the} above formula (5) or (6) is used.
+ ... It is desirable to use 5 mol% or more of a silicon-containing diisocyanate having np of 40 or more.

Since the silicon-containing iminohydantoin-based copolymer of the present invention does not cause a problem of performance deterioration even if it is mixed and used in an arbitrary ratio, the silicon-containing iminohydantoin-copolymer and its multi-block copolymer. Can also be used as a mixture. Further, the silicon-containing iminohydantoin-based copolymer can be used in combination with a conventionally used one such as silicone resin or silicone rubber. However, the advantages of the mixed use are small except for a special case, and therefore, the copolymer of the present invention produced from a diisocyanate according to the purpose as a raw material as described above may be generally used for the overcoat layer.
The overcoat layer of the present invention has a thickness of 0.1 to 7.5 μ.
The thickness is preferably about m, preferably 0.5 to 3.5 μm.

The thermosensitive recording layer can be formed by a method of coating or drying a solution in which a matrix resin, a low molecular weight organic compound, etc. are dispersed or dissolved in a solvent and dried, and the solvent used for forming the thermosensitive recording layer. Can be variously selected depending on the type of matrix resin and low molecular weight organic compound,
Examples thereof include tetrahydrofuran, methyl ethyl ketone, methyl isobutyl ketone, chloroform, carbon tetrachloride, ethanol, toluene and benzene. The low-molecular weight organic compound is precipitated as fine particles and exists in a dispersed state in the heat-sensitive layer obtained not only when the dispersion is used but also when the solution is used.

In the present invention, the matrix resin in the thermosensitive recording layer of the reversible thermosensitive recording medium can form a film,
It is preferable that the film has excellent transparency and is mechanically stable. As such a resin, polyvinyl chloride; vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-
Vinyl alcohol copolymer, vinyl chloride-vinyl acetate-
Vinyl chloride-based copolymers such as maleic acid copolymers and vinyl chloride-acrylate copolymers; polyvinylidene chloride; vinylidene chloride-vinyl chloride copolymers and vinylidene chloride-based copolymers such as vinylidene chloride-acrylonitrile copolymers Polyester; polyamide; polyacrylate; polymethacrylate; polyacrylate-polymethacrylate copolymer; silicone resin and the like. These may be used alone or as a mixture of two or more.

On the other hand, the low molecular weight organic compound may be any one that can change from polycrystal to single crystal by heat in the recording layer, and generally has a melting point of 30 to 200 ° C., preferably 50 to 50 ° C.
A low molecular weight organic compound having a melting point of 150 ° C. is used. Such low molecular weight organic compounds include alkanols; alkanediols; halogenated alkanols; halogenated alkanediols; alkylamines; alkanes;
Alkenes; alkynes; halogenated alkanes; halogenated alkenes; halogenated alkynes; cycloalkanes; cycloalkenes; cycloalkynes; saturated or unsaturated mono- or dicarboxylic acids or their esters, amides or salts; saturated or unsaturated halogenated fatty acids or These esters,
Amides or salts; allylcarboxylic acids or their esters, amides or salts; halogenated allylcarboxylic acids or their esters, amides or salts; thioalcohols; thiocarboxylic acids or their esters, amides or salts; carboxylic esters of thioalcohols And so on. These may be used alone or as a mixture of two or more. The carbon number of these compounds is 10 to 60, preferably 10 to 3
8 and especially 10-30 are preferable. The alcohol group moiety in the ester may be saturated or unsaturated, and may be halogen-substituted. In any case, the low molecular weight organic compound contains at least one oxygen,
Groups containing nitrogen, sulfur or halogen, eg -OH
-, -COOH, -CONH, -COOR, -NH-,
A compound having —S—, —S—S— or —O— is preferable.

More specifically, as these compounds
Is lauric acid, dodecanoic acid, myristic acid, pentade
Canic acid, palmitic acid, stearic acid, behenic acid, nona
Decanoic acid, arachidic acid, heneicosanoic acid, tricosane
Acid, lignoceric acid, pentacosanoic acid, cerotic acid,
Putacosanoic acid, montanic acid, melissic acid and oleic acid
Higher fatty acids such as; methyl stearate, stearic acid
Tetradecyl, octadecyl stearate, lauric acid
Octadecyl, tetradecyl palmitate and behenic acid
Esters of higher fatty acids such as dodecyl; C₁₆H₃₃-OC₁₆H₃₃, C₁₆H₃₃-SC₁₆H₃₃ C₁₈H₃₇-SC₁₈H₃₇, C₁₂H_{twenty five}-SC₁₂H_{twenty five} C₁₉H₃₉-SC₁₉H₃₉, C₁₂H_{twenty five}-S-S-C₁₂H_{twenty five}   And ether or thioether. During ~
However, in the present invention, higher fatty acids, especially palmitic acid, penta
Decanoic acid, nonadecanoic acid, arachidic acid, heneicosane
Acid, tricosanoic acid, stearic acid, behenic acid, lignose
Higher fatty acids having 16 or more carbon atoms such as phosphoric acid
Higher fatty acids having 16 to 24 carbon atoms are preferred.
Preferred.

Further, in order to widen the temperature range in which the material can be made transparent, the low-molecular weight organic compounds shown above may be appropriately combined, or such a low-molecular weight organic compound may be combined with another material having a different melting point. . These are described, for example, in JP-A-63-39378, JP-A-63-130380, Japanese Patent Application No. 63-14754 and Japanese Patent Application No. 1-1.
However, the present invention is not limited to these.

The weight ratio of the low molecular weight organic compound to the resin base material in the heat sensitive layer is preferably about 2: 1 to 1:16, more preferably 1: 2 to 1: 6. When the ratio of the resin base material is less than this, it becomes difficult to form a film in which the low molecular weight organic compound is held in the resin base material, and when it is more than this, it is difficult to make the opacity because the amount of the low molecular weight organic compound is small. Become.

The thickness of the heat sensitive layer is preferably 1 to 30 μm,
2 to 20 μm is more preferable. If the heat-sensitive layer is too thick, the heat sensitivity will decrease and it will be difficult to make it transparent uniformly. On the other hand, if the heat-sensitive layer is too thin, the white turbidity is lowered and the contrast is lowered. Further, the amount of low molecular weight organic compounds in the heat-sensitive layer can be increased to increase the white turbidity.

In addition to the above components, the heat-sensitive layer may contain additives such as a high melting point solvent and a surfactant in order to facilitate the formation of a transparent image. As a high melting point solvent, tributyl phosphate, tri-2-ethylhexyl phosphate, triphenyl phosphate, tricresyl phosphate, butyl oleate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-phthalate. n
-Octyl, di-2-ethylhexyl phthalate, diisononyl phthalate, dioctyl decyl phthalate, diisodecyl phthalate, butylbenzyl phthalate, dibutyl adipate, di-n-hexyl adipate, di-adipate
2-ethylhexyl, di-2-ethylhexyl azelate, dibutyl sebacate, di-2-ethylhexyl sebacate, diethylene glycol dibenzoate, triethylene glycol di-2-ethyl butyrate, methyl acetylricinoleate, butyl acetylricinoleate,
Butyl phthalyl butyl glycolate and acetyl citrate tributyl etc. are mentioned.

As the surfactant and other additives, polyhydric alcohol higher fatty acid ester; polyhydric alcohol higher alkyl ether; polyhydric alcohol higher fatty acid ester, higher alcohol, higher alkylphenol, higher fatty acid higher alkylamine, higher fatty acid amide, Lower olefin oxide adduct of fats and oils or polypropylene glycol; acetylene glycol; Na, Ba, Ca or Mg salt of higher alkylbenzene sulfonic acid; higher fatty acid, aromatic carboxylic acid, higher aliphatic sulfonic acid, aromatic sulfonic acid, sulfuric acid monoester Or Ca, Ba or Mg salt of phosphoric acid mono- or diester; low degree of sulfated oil; poly long chain alkyl acrylate; acrylic oligomer; poly long chain alkyl methacrylate; long chain alkyl methacrylate-amine-containing mono Over copolymer; a styrene - maleic acid copolymer and olefin anhydride - like maleic anhydride copolymer.

In the present invention, a plastic film, a glass plate, a metal plate or the like is used as the support of the reversible thermosensitive recording material as described above.

In order to improve the image contrast of this recording material, it is possible to provide a light reflecting layer on the back surface of the recording layer. In this case, high contrast can be obtained even if the thickness of the recording layer is reduced. Specifically, JP-A 64-140
The method of vapor-depositing Al, Ni, Sn, Au, Ag, etc. described in No. 79 can be mentioned.

For a material whose support has a poor adhesion to a resin such as an Al vapor deposition layer, a method of providing an adhesion layer between the support and the heat sensitive layer may be used. Good. Furthermore, an intermediate layer is provided between the overcoat layer and the reversible recording material described in JP-A-1-133781 in order to protect the reversible recording material from the solvent and monomer components of the overcoat layer forming liquid. Any method may be used. As the material of the intermediate layer, the following thermosetting resins and thermoplastic resins can be used in addition to those listed as the resin base material in the heat sensitive layer. That is, specifically, polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyvinyl butyral, polyurethane, saturated polyester, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, polyamide and the like can be mentioned. Although the thickness of the intermediate layer varies depending on the use, it is preferably about 0.1 to 2 μm. If it is less than this, the protective effect is reduced, and if it is more than this, the thermal sensitivity is lowered.

It is also possible to provide a magnetic recording layer as described in Japanese Utility Model Laid-Open No. 2-3876 and use it as a magnetic reversible thermosensitive recording medium capable of recording by magnetism and heat.

[0038]

EXAMPLES Next, examples and comparative examples will be shown. In addition, in the examples, the intrinsic viscosity is a value measured at 30 ° C. in dimethylformamide at a polymer concentration of 0.5 g / dL. All parts and percentages shown below are based on weight.

Example 1 49 mol% isophorone diisocyanate, 50.5
mol% hydrogen cyanide and 0.5 mol% of a silicon-containing diisocyanate represented by the following formula (7)
-Methylpyrrolidone as solvent in the presence of NaCN 15
The reaction was carried out at a reaction temperature of ° C for 20 hours to obtain a silicon-containing iminohydantoin copolymer. This copolymer has a repeating unit represented by the following formula (8) and has an intrinsic viscosity of 0.
It was 6 dL / g.

[Chemical 7]

Embedded image On a 75 μm thick polyethylene terephthalate (RET) film, 8 parts behenic acid, 2 parts stearyl stearate, 3 parts di (2-ethylhexyl) phthalate, 2 parts
8 parts of vinyl chloride-vinyl acetate copolymer (UCC,
A solution consisting of VYHH) and 200 parts of tetrahydrofuran was applied with a wire bar and dried at 80 ° C. for 3 minutes to provide a heat-sensitive recording layer having a thickness of 15 μm. 10 on this recording layer
90 parts of polyamide resin (CM8000 made by Toray)
A solution consisting of a part of methyl alcohol was applied with a wire bar and dried at 80 ° C. for 1 minute to form an intermediate layer having a thickness of 0.5 μm. An 8% cyclohexanone solution of the iminohydantoin copolymer represented by the formula (8) was applied onto this intermediate layer with a wire bar, and the coating was performed at 80 ° C. for 1 minute, 90 ° C. for 1 minute, and 110 ° C. for 1 minute. A reversible thermosensitive recording medium was obtained by drying with strong wind to provide an overcoat layer having a thickness of 2.5 μm. The dynamic friction coefficient of the overcoat layer was 0.26.

Example 2 37.6 mol% of 1,6 diisocyanate hexane,
11.4 mol% 4,4'-diisocyanate biphenyl, 50.5 mol% hydrogen cyanide and 0.5 mo
Using 1% of a silicon-containing diisocyanate represented by the following formula (9), the same treatment as in Example 1 was carried out to synthesize a silicon-containing iminohydantoin copolymer. This copolymer had a repeating unit represented by the following formula (10) and had an intrinsic viscosity of 0.7 dL / g.

[Chemical 9]

[Chemical 10] A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (10) was used. The coefficient of friction of the overcoat layer was 0.27.

Example 3 45.5 mol% of 3,3'-dichloro-4,4'-diphenyl diisocyanate, 50.5 mol% of hydrogen cyanide and 4 mol% of a silicon-containing diisocyanate represented by the following formula (11) were used. Then, the same treatment as in Example 1 was carried out to synthesize a silicon-containing iminohydantoin copolymer. This copolymer had a repeating unit represented by the following formula (12), had an intrinsic viscosity of 1.1 dL / g and a glass transition point of 200 ° C. or higher.

[Chemical 11]

[Chemical 12] A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (12) was used. The coefficient of friction of the overcoat layer was 0.12.

Example 4 46 mol% 4,4'-diphenylmethane diisocyanate, 50.5 mol% hydrogen cyanide and 3.5 m
Using silicon-containing diisocyanate represented by the following formula (13) in ol%, the same treatment as in Example 1 was carried out to synthesize a silicon-containing iminohydantoin copolymer. This copolymer has a repeating unit represented by the following formula (14), an intrinsic viscosity of 1.2 dL / g and a glass transition point of 20.
It was 0 ° C or higher.

[Chemical 13]

Embedded image A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (14) was used. The coefficient of friction of the overcoat layer was 0.14.

Example 5 46 mol% 4,4'-diisocyanate diphenyl ether, 50.5 mol% hydrogen cyanide and 3.5
A silicon-containing iminohydantoin copolymer was synthesized by treating in exactly the same manner as in Example 1 using mol% of the silicon-containing diisocyanate represented by the following formula (15).
This copolymer has a repeating unit represented by the following formula (16), an intrinsic viscosity of 1.2 dL / g and a glass transition point of 2
It was at least 00 ° C.

[Chemical 15]

Embedded image A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (16) was used. The coefficient of friction of the overcoat layer was 0.14.

Example 6 29.7 mol% 4,4'-diphenylmethane diisocyanate, 50.5 mol% hydrogen cyanide and 1
A silicon-containing iminohydantoin copolymer was synthesized in the same manner as in Example 1 except that 9.8 mol% of the silicon-containing diisocyanate represented by the following formula (17) was used. This copolymer had a repeating unit represented by the following formula (18), had an intrinsic viscosity of 0.9 dL / g and an elongation at break of 50% or more.

[Chemical 17]

Embedded image A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (18) was used. The coefficient of friction of the overcoat layer was 0.05.

Example 7 44.5 mol% 4,4'-diphenylmethane diisocyanate, 50.5 mol% hydrogen cyanide and 5.
The same treatment as in Example 1 was carried out using 0 mol% of the silicon-containing diisocyanate represented by the above formula (7) to synthesize a silicon-containing iminohydantoin copolymer.
This copolymer has a repeating unit represented by the following formula (19), an intrinsic viscosity of 1.4 dL / g and a glass transition point of 2
The elongation at break was 00 ° C or more and 50% or more.

[Chemical 19] A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (19) was used. The coefficient of friction of the overcoat layer was 0.11.

Example 8 34.7 mol% 2,4-toluene diisocyanate, 50.5 mol% hydrogen cyanide and 14.8 mo
Using 1% of the silicon-containing diisocyanate represented by the above formula (9), the same treatment as in Example 1 was carried out to synthesize a silicon-containing iminohydantoin copolymer. This copolymer has a repeating unit represented by the following formula (20), an intrinsic viscosity of 0.6 dL / g, and a glass transition point of 200.
It was above ℃.

Embedded image A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (20) was used. The coefficient of friction of the overcoat layer was 0.11.

Example 9 Example 1 was performed using 44.5 mol% of 3,4'-diisocyanate diphenyl ether, 50.5 mol% of hydrogen cyanide and 5.0 mol% of the silicon-containing diisocyanate represented by the above formula (11). A silicon-containing iminohydantoin copolymer was synthesized in the same manner as described above. This copolymer had a repeating unit represented by the following formula (21), had an intrinsic viscosity of 1.3 dL / g, a glass transition point of 200 ° C. or higher, and a breaking elongation of 50%.

[Chemical 21] A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (21) was used. The coefficient of friction of the overcoat layer was 0.18.

Example 10 29.7 mol% m-phenylene diisocyanate,
16.3 mol% 2,4-toluene diisocyanate, 50.5 mol% hydrogen cyanide and 3.5 mol
% Of the silicon-containing diisocyanate represented by the following formula (22) was treated in the same manner as in Example 1 to synthesize a silicon-containing iminohydantoin multiblock copolymer. This copolymer had a repeating unit represented by the following formula (23), had an intrinsic viscosity of 0.7 dL / g and a glass transition point of 200 ° C. or higher.

[Chemical formula 22] Example 1 except that the silicon-containing iminohydantoin multiblock copolymer represented by the above formula (23) was used.
A reversible recording medium was obtained in the same manner as in. The coefficient of friction of the overcoat layer was 0.06.

Example 11 39.6 mol% 4,4'-diphenylmethane diisocyanate, 2.5 mol% m-xylene diisocyanate, 50.5 mol% hydrogen cyanide and 7.4 m
The silicon-containing iminohydantoin multi-block copolymer was synthesized in the same manner as in Example 1 using ol% of the silicon-containing diisocyanate represented by the above formula (7). The copolymer had a repeating unit represented by the following formula (24), an intrinsic viscosity of 1.3 dL / g, a glass transition point of 200 ° C. or higher, and a breaking elongation of 50%.

[Chemical formula 24] A reversible recording medium was obtained in the same manner as in Example 1 except that the silicon-containing iminohydantoin copolymer represented by the above formula (24) was used. The coefficient of friction of the overcoat layer was 0.13.

Example 12 39.6 mol% 4,4'-diisocyanate diphenyl ether, 5.0 mol% 2,4-toluene diisocyanate, 50.5 mol% hydrogen cyanide and 5.0 mol% represented by the above formula (22). A silicon-containing iminohydantoin multiblock copolymer was synthesized by treating the silicon-containing diisocyanate prepared in the same manner as in Example 1. This copolymer has a repeating unit represented by the following formula (25) and has an intrinsic viscosity of 0.8 dL /
g, the glass transition point was 200 ° C. or higher, and the breaking elongation was 50%.

[Chemical 25] Example 1 except that the silicon-containing iminohydantoin multiblock copolymer represented by the above formula (25) was used.
A reversible recording medium was obtained in the same manner as in. The coefficient of friction of the overcoat layer was 0.05.

Comparative Example 1 A reversible thermosensitive recording medium was obtained in the same manner as in Example 1 except that the reversible thermosensitive recording layer was provided and the intermediate layer and the overcoat layer were not provided.

Comparative Example 2 A reversible thermosensitive recording layer and an intermediate layer were provided in the same manner as in Example 1, and 3 parts of organopolysiloxane (KS-779H, manufactured by Shin-Etsu Silicon Co., Ltd.), 0.01 part, were provided on the intermediate layer. Solution (PL-8, manufactured by Shin-Etsu Silicon Co., Ltd.) and 97 parts of toluene was coated with a wire bar and dried at 80 ° C. for 1 minute to form an overcoat layer having a thickness of 0.12 μm. The medium was obtained.

(Evaluation Method) The reversible thermosensitive recording medium prepared as described above was applied to a thin film thermal head at 0.5 μJ.
After forming an image with the printing energy of / dot, 65 ° C
The operation of reheating until the image is erased was repeated 500 times. The densities of the image part and the non-image part at the 1st, 100th, 300th and 500th times were measured with a Macbeth densitometer RD514 with a black paper on the back surface, and the results are shown in Table 1.

[0054]

[Table 1]

[0055]

The reversible thermosensitive recording medium of the present invention is provided with a heating element such as a thermal head by providing an overcoat layer comprising the silicon-containing iminohydantoin-based polymer having the above-mentioned specific structure on the reversible thermosensitive recording layer. It is possible to suppress the decrease in the transparency of the non-image portion due to the repetition of image formation and deletion. Further, as the polymer,
By using a silicon-containing iminohydantoin-based copolymer having a breaking elongation of 50% or more when formed into a film, the overcoat layer composition is fused or adhered to a heating element such as a thermal head or the vicinity thereof to form an image. It is possible to prevent the deterioration of quality and the occurrence of incomplete erasure. Furthermore, by using a silicon-containing iminohydantoin-based copolymer having a glass transition point of 200 ° C. or higher as the polymer, it is possible to further suppress the above-mentioned decrease in transparency. Furthermore, as the polymer, 0.2
By using the silicon-containing iminohydantoin-based copolymer having a dynamic friction coefficient of 0 or less, the rubbing force generated between the heating element such as a thermal head and the overcoat layer is reduced, and the deformation of the overcoat layer is suppressed. As a result, it is possible to further prevent the above-mentioned decrease in transparency.

[Brief description of drawings]

FIG. 1 is an explanatory diagram when an image is formed / erased by a heat-sensitive layer according to the present invention.

Claims (8)

[Claims] 1. A reversible recording medium comprising a resin matrix and a low-molecular organic compound dispersed in the resin matrix as a main component, and a thermosensitive recording layer whose transparency reversibly changes depending on a temperature change. A reversible thermosensitive recording medium, characterized in that an overcoat layer made of an iminohydantoin-based polymer containing silicon is provided on the thermosensitive recording layer. 2. The iminohydantoin-based polymer containing silicon is a copolymer having a repeating unit represented by the following general formula (1).
The reversible thermosensitive recording medium described. Embedded image (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom or a CN group, a phenyl group, or an alkyl group having 1 to 4 carbon atoms. Or a phenyl group substituted with an alkoxy group or a halogen atom, which may be the same or different.
Has the formula _{-Ph-D-C (L 1} ) (L 2) -C (L 3)
Represents a divalent linking group represented by (L ₄ )-or Ph-D-, and in this formula, L ₁ , L ₂ , L ₃ and L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. And may be the same or different, D is a bond or -E-
(CH ₂ ) m- (where m represents an integer of 1 to 6),
_{-E-Si (CH 3) 2} -, - E-Si (CH 3) (P
h)-and -E-Si (Ph) _2- representing a divalent bonding group, wherein E is a bond or -O-, -S.
_{-, - O-CH 2 -} , - O-CO- and -NH-CO-
Ph which is a divalent linking group selected from
Is bound to the nitrogen atom of the hydantoin ring. B represents a divalent linking group having 2 or more carbon atoms. n, y and z are 1
Represents the above integers. ) 3. The reversible thermosensitive recording medium according to claim 1, wherein the iminohydantoin-based polymer containing silicon is a copolymer having a repeating unit represented by the following general formula (2). . Embedded image (Wherein R ₁ , R ₂ , R ₃ , R ₄ ... Rx + ₁ , Rx + ₂ and Rx +
₃ represents a halogen atom or an alkyl group having 1 to 12 carbon atoms which may be substituted with a CN group, a phenyl group, an alkyl group or an alkoxy group having 1 to 4 carbon atoms, or a phenyl group substituted with a halogen atom. , May be the same or different. A has the formula _{-Ph-D-C (L 1} )
It represents a divalent linking group represented by (L ₂ ) -C (L ₃ ) (L ₄ )-or Ph-D-, and in this formula, L ₁ , L ₂ , L ₃
And L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and may be the same or different, and D is a bond or —E— (CH ₂ ) m— (where m is 1 ~
6 represents an integer of), - E-Si (CH 3) 2 -, - E-S
_{i (CH 3) (Ph)} - and -E-Si (Ph) ₂ - represents a divalent linking group selected from the E represents a bond or -O -, - S -, - O-CH 2 -, -O-CO- and-
It represents a divalent linking group selected from NH-CO-, and Ph contained in A is bound to the nitrogen atom of the hydantoin ring. B represents a divalent linking group having 2 or more carbon atoms. n ₁ ,
n ₂ , ... Np, y and z represent an integer of 1 or more, and x is 3
The above integers are represented, and p represents an integer of 2 or more. ) 4. The reversible thermosensitive material according to claim 1, wherein the iminohydantoin-based polymer containing silicon is a multi-block copolymer having a repeating unit represented by the following general formula (3). recoding media. Embedded image (In the formula, R ₁ , R ₂ , R ₃ and R ₄ are each an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom or a CN group, a phenyl group, or an alkyl group having 1 to 4 carbon atoms. Or a phenyl group substituted with an alkoxy group or a halogen atom, which may be the same or different.
Has the formula _{-Ph-D-C (L 1} ) (L 2) -C (L 3)
(L ₄ )-or Ph-D- represents a divalent linking group, and in this formula, L ₁ , L ₂ , L ₃ and L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. And may be the same or different, D is a bond or -E-
(CH ₂ ) m- (where m represents an integer of 1 to 6),
_{-E-Si (CH 3) 2} -, - E-Si (CH 3) (P
h)-and -E-Si (Ph) _2- , which represents a divalent linking group, wherein E is a bond or -O-, -S.
_{-, - O-CH 2 -} , - O-CO- and -NH-CO-
A divalent linking group selected from
Is bound to the nitrogen atom of the hydantoin ring. B ₁ , B ₂
Bq represents a divalent linking group having 2 or more carbon atoms. n, y and z ₁ , z ₂ ... Zq represent an integer of 1 or more, and q represents an integer of 2 or more. ) 5. The reversible thermosensitive material according to claim 1, wherein the iminohydantoin-based polymer containing silicon is a multi-block copolymer having a repeating unit represented by the following general formula (4). recoding media. [Chemical 4] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ ... Rx, Rx + ₁ , Rx + ₂ and Rx + ₃ are an alkyl group having 1 to 12 carbon atoms which may be substituted with a halogen atom or a CN group, or A phenyl group, or an alkyl group or an alkoxy group having 1 to 4 carbon atoms or a phenyl group substituted with a halogen atom, which may be the same or different, and A is of the formula -Ph-D-C.
(L ₁ ) (L ₂ ) —C (L ₃ ) (L ₄ ) — or Ph-D— represents a divalent linking group, and in this formula L ₁ ,
L ₂ , L ₃ and L ₄ represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms and may be the same or different, and D is a bond or —E— (CH ₂ ) m- (. However, m is an integer of 1~6), - E-Si ( CH 3) 2
-, - E-Si (CH 3) (Ph) - and -E-Si
Represents a divalent linking group selected from (Ph) ₂
Is a bond or —O—, —S—, —O—CH ₂ —, —
It represents a divalent linking group selected from O—CO— and —NH—CO—, and Ph contained in A is bound to the nitrogen atom of the hydantoin ring. B ₁ , B ₂ ... Bq represent a divalent bonding group having 2 or more carbon atoms. n ₁ , n ₂ , ... Np, y, z ₁ , z ₂
... zq represents an integer of 1 or more, x represents an integer of 3 or more, and p and q represent integers of 2 or more. ) 6. The iminohydantoin-based polymer containing silicon has a breaking elongation of 50% or more when formed into a film.
Or the reversible thermosensitive recording medium according to item 5. 7. The reversible thermosensitive recording medium according to claim 1, wherein the silicon-containing iminohydantoin-based polymer has a glass transition point of 200 ° C. or higher. . 8. The reversible thermosensitive recording medium according to claim 1, wherein the iminohydantoin-based polymer containing silicon has a dynamic friction coefficient of 0.20 or less.