JPH10297110A - recoding media - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a recording medium capable of performing clear recording in a short time and capable of reversible recording and erasing. SOLUTION: The weight average molecular weight obtained from an organic diisocyanate compound and a glycol having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton is from 5,000 to 300,
A recording medium comprising a substrate (film, synthetic paper, glass) provided with a recording layer having a base material of 000 non-crosslinked polyurethane resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyurethane recording medium capable of recording and erasing a desired graphic by utilizing the shape memory performance of polyurethane. Specifically, it has a recording layer made of a specific polyurethane resin, and the resin is locally treated with its glass transition point (hereinafter abbreviated as Tg).
By heating as described above, deforming to a certain shape, recording the information by fixing the shape by rapidly cooling it to Tg or less while deforming it, and heating the recording portion or the whole to Tg or more. The present invention relates to a reversible recording medium capable of erasing a recording by reversing the deformation.

[0002]

2. Description of the Related Art Shape memory polyurethane resin (hereinafter referred to as SM)
As a recording medium using (abbreviated as R), a method using a specific polymer diol (JP-A-1-282209),
Foam (JP-A-2-92912), linear polyurethane elastomer (JP-A-61-293214, JP-A-2-293214)
-92914), cross-linked polyurethane (JP-A 7-1)
No. 25440) is known. However, since recording and erasing are slow or the amount of deformation is insufficient, a formed figure is unclear and a highly practical recording medium is used. Had not been obtained. Further, Japanese Unexamined Patent Publication No.
No. 183258 discloses an optical recording medium having a recording layer made of a shape memory resin on a substrate, wherein the shape memory resin is a urethane resin having a weight ratio of a side chain portion to a main chain portion of 1/99 to 50/50. An optical recording medium capable of erasing and repetitively recording is disclosed in Japanese Patent Application Laid-Open No. 8-18664.
No. 1 discloses an optical recording medium having a recording layer made of a shape memory resin on a substrate, wherein the shape memory resin comprises a urethane resin and a cross-linking agent, and the cross-linking point concentration is 1 to 1000 μe.
An erasable and repeatable optical recording medium characterized by q / g is proposed. These optical recording media can improve the speed of recording and erasing, but recently, with the development of information equipment, higher speeds of recording and erasing are expected.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording medium in which the speed of recording and erasing is fast, the amount of deformation is large, and the figure is clear, in view of the above situation.

[0004]

SUMMARY OF THE INVENTION The present invention provides a recording medium having a recording layer made of a polyurethane resin having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton in a molecular chain.

[0005]

[Function] Since the polyurethane resin has a bulky (bulgy) bridged hydrocarbon skeleton or spiro hydrocarbon skeleton in the molecular chain, the difference (change) in the elastic modulus before and after Tg is large, so that large deformation can be easily obtained, and recording and erasing can be easily performed. Is improved, and a clear figure is obtained.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The recording medium of the present invention is a recording medium having a recording layer made of a polyurethane resin having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton in a molecular chain.
Information is recorded by deforming the polyurethane resin of the recording layer locally into a shape heated above its glass transition point, quenching it below the glass transition point while fixing it, and fixing its shape. A reversible recording medium capable of erasing the recording by heating the recording portion or the whole to a temperature equal to or higher than the glass transition point to restore the deformation.

[0007] The recording medium of the present invention can be used as a reversible thermosensitive recording medium or a reversible optical disk. Polyurethane resin: The polyurethane resin as the base resin of the recording layer has a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton in its molecular chain. Here, the bridged hydrocarbon skeleton is described in, for example, Kazuo Hata, “Command of Organic Compounds” (199).
As shown on pages 29-31 of September 27, 5th Revised No. 27, published by Baifukan Co., Ltd., bicyclic bridged cyclic hydrocarbons in which usually two rings share two or more atoms, bicyclic systems Refers to a skeleton containing a cross-linked cyclic hydrocarbon such as tricyclo or tetracyclo further cross-linked, specifically,

[0008]

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And the like. Also, as described on page 31 of the magazine, a spiro hydrocarbon skeleton has a spiro bond in which only one atom is made common to two rings, and two alicycles are It is a spiro hydrocarbon constituted by sharing one carbon element. Such a polyurethane resin is, for example, an organic diisocyanate compound (a ₁ ) and a glycol (a) having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton and a molecular weight of 100 to 400.
₂ ) If necessary, it is obtained by reacting with another polyol (a ₃ ). This polyurethane resin has a weight average molecular weight of 5,000 to 300,000, preferably 15,000 to 150,000, and a glass transition point of 50.
A non-crosslinked polyurethane resin having a temperature of from 130 to 130C, preferably from 70 to 120C, is suitable. When non-crosslinked,
There is an advantage that a curing process (crosslinking step) is not required at the time of manufacturing the recording medium, and that there is no need to worry about the pot life of the resin.

(A ₁ ) Organic diisocyanate compound: Examples of the organic diisocyanate compound used for producing the polyurethane resin of the present invention include paraphenylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-
Aromatic diisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene-1,5-diisocyanate, tolidine diisocyanate, hexamethylene diisocyanate, lysine methyl ester diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid Aliphatic diisocyanate such as diisocyanate, isophorone diisocyanate, alicyclic diisocyanate such as 4,4'-methylenebis (cyclohexyl isocyanate), ω, ω'-diisocyanate dimethylcyclohexane, xylylene diisocyanate, α, α, α ', α'- Examples thereof include aliphatic diisocyanates having an aromatic ring such as tetramethylxylylene diisocyanate. Among them, diisocyanates having an aromatic ring, particularly 4,4'-diphenylmethane diisocyanate are preferred.

(A ₂ ) Glycol having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton: An example of a glycol having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton used in the production of the polyurethane resin of the present invention is bicyclo [4] .2.0] octane-7,8-diol, bicyclo [2.2.1] heptane-2,7-diol, bicyclo [2.2.1] heptane-2,3-dimethyl-2,3-
Diol, bicyclo [4.4.0] decane-3,4-diol, bicyclo [4.4.0] decane-2,3-diol, bicyclo [4.4.0] decane-1,6-diol, Curane-3,4-diol, pinane-2,3-diol, pinane-2,10-diol, bornan-2,3
-Diol, bornane-2,5-diol, bornane-
2,6-diol, bicyclo [3.2.1] octane-
Bicyclic hydrocarbon derivatives such as 1,8,8-trimethyl-2,4-diol, bicyclo [2.2.1] hept-2-ene-5,6-dimethanol, and karan-3,4-diol Tricyclo [5.2.1.0 ^2.6 ] dimethanol,
Tricyclic hydrocarbon derivatives such as perhydrophenanthrene-2,10-diol and perhydrophenanthrene-9,10-diol; spiro [3.3] heptane-2,6-
Spiro hydrocarbon derivatives such as dimethanol and spiro [3.3] heptane-2,6-dimethyldimethanol. Among them, the following formula (I) is preferable.

[0012]

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The compound represented by the formula (1) is particularly preferably tricyclo [5.2.1.0 ^2.6 ] dimethanol.

(A ₃ ) Other polyols: (a ₂ )
In addition to glycols derived from bridged hydrocarbons or spiro hydrocarbons, other polyols as a glycol component for the purpose of adjusting the glass transition point of the resulting urethane resin and adjusting the balance between flexibility and rigidity, such as molecular weight Is 500
Polyether polyols, polyester polyols of up to 10,000 and other molecular weights of 500 to 10,000
Polyol; and other short-chain glycols having a molecular weight of less than 50 to less than 500 can be used in combination.

Examples of the polyether polyol include polyether diol, polyether ester diol, and a mixture of two or more thereof. As the polyether diol, those obtained by homopolymerizing or copolymerizing an alkylene oxide, for example, polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene-propylene glycol, polytetramethylene ether glycol, polyoxyhexamethylene ether glycol, And polyoxyoctamethylene ether glycol and mixtures of two or more thereof. Polyetherester diols include those obtained by reacting a mixture of ether-containing diols or other glycols with dicarboxylic acids or their anhydrides, or by reacting polyester glycols with alkylene oxides, such as poly (poly Tetramethylene ether) adipate and the like.

As the polyester diol, dicarboxylic acids (succinic acid, glutaric acid, adipic acid, sebacic acid,
Fumaric acid, maleic acid, phthalic acid, etc. or their anhydrides and glycols (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butane) Diol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-methyl-2-propyl- 1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 2,
2,4-trimethyl-1,3-pentanediol, 2-
Such as ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 1,8-octamethylene glycol, 2-methyl-1,8-octamethylene glycol, and 1,9-nonanediol. Aliphatic glycols, alicyclic glycols such as bishydroxymethylcyclohexane, xylylene glycols, aromatic glycols such as bishydroxyethoxybenzene, and N-alkyldialkanolamines such as N-methyldiethanolamine). Such as polyethylene adipate, polybutylene adipate, polyhexamethylene adipate, polyethylene / propylene adipate, etc., or polylactone diols obtained using the above diols as initiators, such as polycaprolactone diol, polymethyl butyl Rorakuton and mixtures of two or more thereof. Most preferred as the polyester polyol is polybutylene adipate.

Other polyols include poly (1,6)
-Hexylene) carbonate, poly (3-methyl-1,
Polyolefin polyols such as polycarbonate diols such as 5-pentylene) carbonate, polybutadiene polyol, hydrogenated polybutadiene polyol, and hydrogenated polyisoprene polyol. The molecular weight of the polyol is from 500 to 10,000, preferably from 800 to 6,000, more preferably from 1,000 to 1,000.
4,000.

Examples of short-chain glycols having a molecular weight of 50 to less than 500 include ethylene glycol, diethylene glycol, triethylene glycol, 2-methyl-1,3
-Propylene glycol, propylene glycol, dipropylene glycol, 1,2-butanediol, 1,3
-Butanediol, 1,4-butanediol, 1,5-
Pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol, 2-ethyl-1,3-hexane glycol, 2,
2,4-trimethyl-1,3-pentanediol, 3,
3-dimethylolheptane, 1,9-nonanediol,
Examples thereof include aliphatic glycols such as 2-methyl-1,8-octanediol, alicyclic glycols such as cyclohexanedimethanol, aromatic glycols such as bishydroxyethoxybenzene, and N-alkyldiethanolamines such as N-methyldiethanolamine. .

It is to be noted that a part or all of the short-chain glycol can be substituted with a trifunctional or higher functional polyol, monoalcohol, low molecular weight diamine or monoamine. 3
Examples of the polyol having a higher functionality include glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, erythritol, sorbitol, pentaerythritol,
Examples of monoalcohols such as dipentaerythritol include methanol, ethanol, propanol, butanol, and hexanol. As the low molecular weight diamine, ethylene diamine, propylene diamine, hydrazine,
Aliphatic diamines such as 2,4,4-trimethylhexamethylenediamine, piperazine, cyclohexanediamine,
Examples of alicyclic diamines such as mensendiamine, isophoronediamine, and 4,4'-methylenebis (cyclohexylamine), and examples of monoamines include methylamine, ethylamine, butylamine, dibutylamine, ethanolamine, and diethanolamine.

Production of polyurethane resin: The production of the polyurethane resin of the present invention is carried out by a one-shot method, a prepolymerization method or the like using the above-mentioned resin raw materials according to a known method. As a solvent for producing the polyurethane, usually, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone,
Ketones such as isophorone, esters such as ethyl acetate, butyl acetate, and cellosolve acetate, hydrocarbons such as benzene, toluene, xylene, and hexane, and some alcohols such as diacetone alcohol, isopropanol, secondary butanol, and tert-butanol Examples thereof include chlorides such as methylene chloride and chloroform, ethers such as tetrahydrofuran and diethyl ether, and aprotic polar solvents such as dimethylformamide, N-methylpyrrolidone and dimethylsulfoxide.

As a catalyst for producing the polyurethane, an ordinary urethane-forming reaction catalyst is used. For example, tin-based compounds such as dibrutin dilaurate, dioctyltin dilaurate, dibutyltin dioctoate, and stannas octoate; iron-based compounds such as iron acetylacetonate and ferric chloride; tertiary amine-based compounds such as triethylamine and triethylenediamine; Can be

In the resin raw material, the (a ₁ ) diisocyanate comprises 10 to 90% by weight, preferably 45 to 90% by weight, of the structural units derived from diisocyanate in the polyurethane resin.
The amount of (a ₂ ) the glycol having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton in an amount of 70% by weight is from 10 to 80% by weight, preferably 15 to 80% by weight, of the structural units derived from the glycol in the obtained polyurethane resin. 50 wt%, an amount comprising 15 to 50 wt% and optimally, the polyol having a molecular weight of 500 to 10,000 of (a ₃₎ 0
% By weight, preferably 5% by weight or less, having a molecular weight of 100 to 5
The short-chain glycol of less than 00 is used in an amount of 0 to 15% by weight, preferably 1 to 10% by weight.

These materials have a polyurethane resin having a glass transition point of 50 to 130 ° C., preferably 70 to 1 ° C.
The type and amount used are selected so that the temperature will be 20 ° C. The weight average molecular weight of the polyurethane resin is from 5,000 to 30.
0000, preferably 10,000-20,000,
Particularly preferably, it is 15,000 to 150,000.
If the weight average molecular weight is less than 5,000, shape resilience, coating film strength, solvent resistance, etc. decrease, and if it exceeds 300,000, the viscosity of the resin solution increases, and workability such as application to a substrate decreases. .

The correlation between the characteristics of the polyurethane resin and the performance as a recording medium is presumed as follows. The polyurethane resin is a non-crosslinked type, and the raw material (a ₂ )
Since the glycol component is bulge, the difference (change) in elastic modulus before and after Tg is large, and large deformation is easily obtained. The polyurethane resin has more hard segments than the conventional polyurethane resin, the Tg is appropriately increased, and the recording and erasing speed is faster than that of the conventional polyurethane resin.

Recording medium: In order to produce a recording medium using the above-mentioned polyurethane resin, a solution obtained by dissolving the polyurethane resin in a solvent such as dimethylformamide or pyrrolidone is mixed with glass, polycarbonate, polymethyl methacrylate or polyethylene terephthalate. , A substrate such as a synthetic paper or other film, sheet, or molded body, is coated by a method such as dip coating, bar coating, or spin coating, and dried to form a recording layer film on the surface of the substrate, or a polyurethane resin. Is extruded on a substrate, or an extruded polyester resin film is bonded to the surface of the substrate using an adhesive to produce a recording medium.

Depending on the use of the recording medium, a near-infrared light absorbing agent such as phthalocyanine, naphthalocyanine polymethine, diimmonium, thiol or quinolinol metal complex may be blended in the recording layer as a heat source, or between the substrate and the shape memory layer. May be provided with a dielectric layer, or a protective coat layer may be provided on the surface of the recording layer (see JP-A-8-1856).
No. 41). Specifically, when the recording medium of the present invention is used as a reversible thermosensitive recording medium, a magnetic card member provided with a magnetic recording layer on the surface can be used as the substrate. In this case, the reversible thermosensitive recording layer may be provided on the magnetic layer on the substrate surface or on the opposite surface. Further, it may be provided on the entire surface (front and back surfaces) of the substrate, or may be provided on a part thereof.

In providing the recording layer of the present invention on the magnetic card member, an undercoat layer may be interposed if necessary to improve the adhesion to the substrate. In order to further improve the visibility, a colored layer, Al, A
A metal reflective layer such as g or Sn may be provided. Such a magnetic card having a reversible thermosensitive recording layer can be widely used, such as a highway card, a JR orange card, various prepaid cards used in department stores, supermarkets and the like, and a stored fair card. As a heating means for recording or erasing the recording medium of the present invention, a thermal head used for a thermal transfer printer, a semiconductor laser beam or a heat roll used for a laser beam printer, or the like is used.

[0028]

The present invention will be described in more detail with reference to the following examples. Example 1 Production of polyurethane resin: In a four-necked flask equipped with a stirrer, a reflux condenser, a dropping funnel and a thermometer, 100 parts of tricyclo [5.2.1.0 ^2.6 ] dimethanol was added.
31.6 parts of ethylene glycol and 902 parts of N, N-dimethylformamide were charged, and the mixture was heated to 60 ° C. with stirring and stirred at the same temperature for 1 hour to form a uniform solution.
The temperature was raised to 70 ° C. Next, 4,4'-diphenylmethane diisocyanate 25 heated to 70 ° C and melted.
5.0 parts were dropped into the flask while stirring, and reacted for 4 hours while maintaining the temperature in the flask at 70 ° C., 644 parts of methyl ethyl ketone was added, and the mixture was diluted by stirring at 60 ° C. for 1 hour. Polyurethane resin solution (resin solid content 2
0% by weight, viscosity at 25 ° C. 500 mPa · S, weight average molecular weight of resin 30,000, glass transition point 112 of resin
° C).

* 1: Molecular weight measurement method The molecular weight of the obtained polyurethane resin was measured using a GPC apparatus (manufactured by Tosoh Corporation, HLC-8020, column G300).
0HXL / G2000HXL / G6000HXL). A tetrahydrofuran solution having a resin solid content of 0.2% by weight was prepared, an injection amount was 20 μl, and a flow rate was 1.0 ml / min.
The pressure was measured at 100 kg / cm ² at RI detector RANGE32, and the weight average molecular weight in terms of standard polystyrene was calculated.

* 2: Viscosity measurement method The viscosity of the obtained polyurethane resin solution was measured using an E-type viscometer (VISCONIC EHD-R, Tokyo Keiki Co., Ltd.).
Manufactured). Measurement temperature 25 ° C, sample amount 1.5
ml, measured with a standard rotor (1 ° 34 ′).

Production of recording medium: thickness 150 as substrate
The above polyurethane resin solution is applied to the surface of a biaxially stretched polyethylene terephthalate film having a thickness of 10 μm by using an applicator and dried at 80 ° C. for 10 hours.
A recording medium having a total thickness of 160 μm and a recording layer of

Recording and erasing test: When recording was performed on the recording medium using a commercially available word processor "OASYS LIGHTS" (a product of Fujitsu Ltd.), characters could be visually observed. Thereafter, when the recorded matter was brought into contact with a hot plate having a surface temperature of 110 ° C. for 0.2 seconds, characters were erased.

Example 2 On the surface of a 100 μm-thick polycarbonate disk,
A solution obtained by adding 5 parts by weight of vanadyl phthalocyanine to 100 parts of the polyurethane resin solution (concentration: 20% by weight) obtained in Example 1 was applied using a spin coater, dried at 100 ° C. for 5 hours, and dried to form a recording layer having a thickness of 1 μm. To form a total thickness of 1
A recording medium of 01 μm was obtained. Using a commercially available CD writer (CDU524R, manufactured by Sony Corporation) as a recording medium, recording was performed, and writing and erasing of information were attempted, and both were possible.

[0034]

According to the present invention, the recording medium having a recording layer having a specific structure of a shape memory polyurethane resin as a base material on the surface of a substrate such as a film can record and erase data in a short time.

Claims (5)

[Claims] 1. A recording medium having a recording layer made of a polyurethane resin having a bridged hydrocarbon skeleton or a spiro hydrocarbon skeleton in a molecular chain. 2. A non-crosslinked polyurethane having a weight average molecular weight of 5,000 to 300,000 obtained from an organic diisocyanate compound and a glycol having a bridged hydrocarbon skeleton or a glycol having a spiro hydrocarbon skeleton. The recording medium according to claim 1, which is a resin. 3. The polyurethane resin according to claim 2, wherein a constituent unit based on a glycol having an alicyclic hydrocarbon skeleton having a bridged hydrocarbon accounts for 10 to 80% by weight of the polyurethane resin. The recording medium according to the above. 4. A glycol having an alicyclic hydrocarbon skeleton having a bridged hydrocarbon group is represented by the formula (I): The recording medium according to claim 2, which is a compound represented by the formula: 5. The recording medium according to claim 1, wherein the polyurethane resin has a glass transition point of 50 to 130 ° C.