JPH09315013A - Reversible thermal recording material composition and prepaid card using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable negative type recording by using compounds which satisfy a specified physical property relation as two kinds of low molecular crystalline compounds, in a reversible thermal recording material composition wherein the two kinds of low molecular crystalline compounds are mixed and dispersed into a high molecular resin base material and a light transparency changes according to a cooling state. SOLUTION: In a reversible thermal recording material composition, two kinds of low molecular crystalline compounds are mixed and dispersed into a high molecular resin base material and light transparency changes according to a cooling state. The low molecular crystalline compounds which satisfy formulas I and II are used. In the formulas, S1 and S2 represent compatibility indexes with the high molecular resin base material. The compatibility indexes are regulated by a formula, S=1-(ΔHm /ΔHM) when a heat quantity necessary for dissolving the whole crystal of the low molecular crystalline compound is ΔHm and a heat quantity necessary for dissolving the same crystal low molecular compound simple substance of the same quantity is ΔHM. Tg1 and Tg2 represent glass transition temperatures of the high molecular resin base material when it is cooled, and Tc1 and Tc2 represent extrapolated crystallization start temperatures of the compound.

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 material composition, and more particularly to a reversible thermosensitive recording material composition capable of repeatedly displaying and erasing a visible image by a negative recording system which is the reverse of the conventional one, and the reversible thermosensitive recording material. The present invention relates to a prepaid card using a recording material composition.

[0002]

2. Description of the Related Art A commuter pass for a transportation period, an admission permit to an event venue or a building, etc. is used repeatedly every day, but
There is no way to check for illegal boarding or entry. recent years,
A check method using a magnetic card is being adopted in some parts, but since the recorded contents to be checked cannot be seen visually,
There is a risk of omission of check due to equipment trouble,
Both the administrator and the user felt inconvenient.

Also, in various prepaid cards,
Although a magnetic card or an IC card is used, the recorded contents cannot be directly visually inspected, so that the payment amount and the remaining amount cannot be easily checked, which is inconvenient in terms of guaranteeing the contents to the user.

In order to improve this, a visibly recordable card such as a commuter pass, an admission ticket, various prepaid cards, etc. can be visually recorded, and a recording provided with a reversible thermosensitive recording layer to erase it. The material is known.
As the recording method, for example, a recording material in which an organic low molecular weight substance is dispersed in a polymer resin base material is used, and a step of making the recording layer transparent in a specific temperature region by heating,
A method comprising the step of making the recording layer cloudy by heating it to a temperature higher than that, and making it possible to visually read information due to the difference in contrast (Japanese Patent Laid-Open No. 54-119377 and Japanese Patent Laid-Open No. 55-154198). No. publication) is known. Since these recording materials have a very narrow temperature range showing a high light transmittance, it is difficult to make them transparent, and it is very difficult to control the temperature of printing and erasing. Also,
In order to solve this problem, there is a recording material using one or more kinds of saturated aliphatic dicarboxylic acids as an organic low molecular compound (Japanese Patent Laid-Open No. 2-1363).
The recording characteristics are shown in which the material is cooled to be transparent after heating at a low temperature and becomes opaque (whitening) after being heated at a high temperature. Therefore, a positive type recording system is used in which the entire recording material is heated at a low temperature with a stamp or a roll to erase (make transparent) and is heated by a thermal head to make printing (opaque, cloudy). Therefore,
Printing was done in white letters, which was a visual problem.

[0005]

As described above, according to the prior art, since the temperature range showing a high light transmittance is very narrow,
There is a problem that it is difficult to make transparent, and it is very difficult to control the temperature of printing and erasing. Further, since printing is performed in white characters, there is a problem in visual recognition.

The present invention solves the above-mentioned conventional problems,
A reversible thermosensitive recording material composition which is easy to control the temperature for printing and erasing, enables negative type recording, and has excellent visibility, and a reusable prepaid using such a thermosensitive recording material composition. The purpose is to provide a card.

[0007]

In order to achieve the above object, in the heat-sensitive recording material composition according to the present invention, two kinds of crystalline low molecular weight compounds are mixed and dispersed in a polymer resin matrix, and the first
When cooled from the temperature region T ₁ and, in the reversible thermosensitive recording material composition transmittance of light changes when the cooling from the T ₁ higher than the second temperature region T _2, wherein the two kinds of crystalline The low molecular weight compound simultaneously satisfies the following formulas (1) and (2);

[0008]

[Equation 7] | S ₁ −S ₂ |> 0.1 (1)

[0009]

T _g2 <T _c1 ≦ T _c2 <T _g1 (2) where S ₁ and S ₂ are the compatibility indexes of the two crystalline low molecular weight compounds with the polymer resin matrix ( S), and the compatibility index S is ΔH _m , which is the amount of heat required to melt all the crystals of the crystalline low molecular weight compound dispersed in the polymer resin matrix, and the same amount of the same crystalline low molecular weight compound. Let ΔH _M be the amount of heat required to melt a simple substance,

[0010]

## EQU9 ## S = 1- (ΔH _m / ΔH _M ) (3) where T _g1 and T _g2 are the reversible thermosensitive material composition in the first temperature region T ₁ and the second temperature, respectively. It is a glass transition temperature of the polymer resin matrix when heated to a region T ₂ and then cooled, where T _c1 and T _c2 are the first temperature region T ₁ and the second temperature region of the reversible thermosensitive material composition, respectively. It is the extrapolation crystallization start temperature of the compound having the lowest crystallization temperature among the crystalline low molecular weight compounds dispersed in the polymer resin base material when heated to the temperature region T ₂ and cooled.

Further, the reversible thermosensitive recording material composition according to the present invention comprises a crystalline resin low molecular compound in a high molecular resin matrix.
Reversible thermosensitive recording material composition in which the light transmittance changes when mixed from one or more species and cooled from the first temperature region T ₁ and when cooled from the second temperature region T ₂ higher than T ₁ In the compound, each of the three or more types of crystalline low molecular weight compounds has a mole fraction of m _x (x = 1, 2, 3 ...) Dispersed in the polymer resin matrix, The following formulas (4) and (5) are simultaneously satisfied, where S _x is the compatibility index of each of the above crystalline low molecular weight compounds with the polymer resin base material;

[0012]

[Number 10] _{| m y S y -m z S} z |> 0.1 (4)

[0013]

T _g2 <T _c1 ≦ T _c2 <T _g1 (5) where m _y S _y and m _z S _z are crystalline low molecular weight compounds in which m _x S _x has the maximum value and the minimum value, respectively. Is the m _x S _x , and the compatibility index S is ΔH _m , the amount of heat required to melt all the crystals of the crystalline low molecular weight compound dispersed in the polymer resin matrix, and the same amount of the same crystallinity. Let ΔH _M be the amount of heat required to melt the low molecular weight compound alone,

[0014]

## EQU12 ## S = 1- (ΔH _m / ΔH _M ) (6), where T _g1 and T _g2 are the first temperature region T ₁ and the second temperature of the reversible thermosensitive material composition, respectively. It is a glass transition temperature of the polymer resin matrix when heated to a region T ₂ and then cooled, where T _c1 and T _c2 are the first temperature region T ₁ and the second temperature region of the reversible thermosensitive material composition, respectively. It is the extrapolation crystallization start temperature of the compound having the lowest crystallization temperature among the crystalline low molecular weight compounds dispersed in the polymer resin base material when heated to the temperature region T ₂ and cooled.

Here, the reversible thermosensitive material composition becomes opaque when cooled from the first temperature region T _1, and becomes transparent when cooled from the second temperature region T ₂ .

The prepaid card according to the present invention is characterized in that a magnetic recording layer and a heat-sensitive recording layer comprising the above-mentioned reversible heat-sensitive recording material composition are provided on a resin base material.

Here, the magnetic recording layer is provided on one surface of the resin substrate, and the thermosensitive recording layer is provided on the other surface of the resin substrate via a reflective layer. It is preferable that the protective layer is provided on the first protective layer, and the printed layer having an opening is provided on the protective layer.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Conventionally, in order to solve the above-mentioned problems, studies have been conducted by paying attention to the type of resin base material, the composition or the type of low molecular weight compound dispersed therein, the melting point and the like. Focusing on the compatibility between the resin base material and the low molecular weight compound dispersed therein, the inventors have defined an index indicating the compatibility as the compatibility index S of the low molecular weight compound dispersed in the resin base material, and the compatibility index S And the relationship between recording characteristics were examined. Here, the compatibility index S is ΔH _m , which is the amount of heat required to melt all the crystals of the crystalline low molecular weight compound dispersed in the polymer resin matrix, and the same amount of the same crystalline low molecular weight compound alone. When the amount of heat required to melt is ΔH _M , the following formula

[0019]

## EQU13 ## S = 1- (ΔH _m / ΔH _M ) (3) More specifically, when the temperature of the reversible thermosensitive recording material composition is raised at a temperature rising rate of 10 ° C./min using a differential thermal scanning calorimeter, the crystalline low-molecular compound dispersed in the base material When the amount of heat required to melt all the crystals is ΔH _m , and the amount of heat required to melt an equivalent amount of a crystalline low molecular weight compound not dispersed in the polymer resin matrix is ΔH _M , the phase is The solubility index S is defined by the equation (3). 1 and 2 show the differential thermal analysis results of the reversible thermosensitive material composition and the crystalline low molecular weight compound. The areas of the respective peaks in FIGS. 1 and 2 are ΔH _m and ΔH _M , respectively. Furthermore, the present inventors have paid attention to the glass transition temperature Tg of the resin base material after the crystalline low molecular weight compound is dispersed and the crystallization temperature Tc of the dispersed crystalline low molecular weight compound, and Tg, Tc
The relationship between the recording characteristics and the recording characteristics was earnestly examined.

When there are two kinds of crystalline low molecular weight compounds dispersed in the resin base material,

[0021]

[Equation 14] | S ₁ −S ₂ |> 0.1 (1)

[0022]

When T _g2 <T _c1 ≦ T _c2 <T _g1 (2) is satisfied at the same time, and when three or more crystalline low molecular weight compounds are dispersed in the polymer resin matrix,

[0023]

Equation 16] _{| m y S y -m z S} z |> 0.1 (4)

[0024]

When T _g2 <T _c1 ≤ T _c2 <T _g1 (5) is satisfied at the same time, after heating at a low temperature, the mixture is cooled to become cloudy,
It has been found that a reversible thermosensitive recording material composition can be obtained which is transparent after being heated at a high temperature and cooled, and has a wide temperature range in which it can be transparent.

However, S ₁ and S ₂ represent the compatibility index (S) to the respective polymer resin base materials when two kinds of crystalline low molecular weight compounds are used, and m _x (x = 1, 2, 3) ...), when three or more types of crystalline low molecular weight compounds are present, the molar fraction of each dispersed in the polymer resin matrix, S _x (x = 1,
2, 3, ...) is a compatibility index with each of the polymer resin base materials in the case of three or more crystalline low-molecular compounds, m _y S _y
And m _z S _z is a m _x S _x m _x S _x each on crystalline low molecular compound having a maximum value and minimum value, T _g1 and T _g2 are respectively the reversible thermosensitive material composition First temperature range T ₁ and second temperature range T ₂
The glass transition temperatures, T _c1 and T _c2 , of the polymer resin base material when heated up to and after being cooled to the first temperature region T ₁ and the second temperature region T _{2 of the} reversible thermosensitive material composition, respectively.
It is the extrapolation crystallization start temperature of the compound showing the lowest crystallization temperature among the crystalline low molecular weight compounds dispersed in the polymer resin base material when heated up to and then cooled.

The blending ratio of the polymer resin base material / crystalline low molecular weight compound is preferably 95/5 to 25/75 by weight, and 8
It is more preferably 5/15 to 50/50. When the amount of the resin base material is more than 95/5, it does not become cloudy due to low temperature heating and the contrast decreases. Further, when the amount of the crystalline low molecular weight compound is more than 25/75, the film forming property is deteriorated.

FIG. 3 shows static characteristics of the reversible thermosensitive recording material composition according to the present invention. As shown, when heated and cooled in the temperature range T ₁ , the reflection density decreases, that is, becomes opaque,
It becomes cloudy. It becomes transparent when it is cooled after being heated in the higher temperature range T ₂ . Therefore, when this composition is used, the entire recording material is heated at a low temperature with a stamp or a roll to erase (opaque or opaque) it, and the thermal head partially heats it to make it transparent. Will be possible. For example, if a black base material is used as the base of the recording layer, a paper-like recording material capable of printing black on a white background can be realized.

FIG. 4 is a perspective view of an example of a card using the reversible thermosensitive recording material composition according to the present invention in the recording layer,
FIG. 5 is a sectional view thereof. 4 and 5 show an entrance ticket as an example. A known reflection layer 2, a recording layer 3 made of a reversible thermosensitive recording material composition, a transparent protective layer 4, and a printing layer 5 are sequentially laminated on the surface of a synthetic resin substrate sheet 1 such as polyethylene terephthalate. Necessary information is printed on the surface of the printing layer 5, and a visible recording display window 6 which is a window for visually recognizing the recorded contents recorded on the recording layer 3 is opened. A magnetic recording layer 7 and a protective printing layer 8 are laminated on the back surface of the synthetic resin substrate sheet 1.

In this card, when the recording area corresponding to the visible recording display window 6 of the recording layer 3 is heated and cooled in the temperature area T ₁ shown in FIG. 3 by a heating means such as a heating stamp or a heating roll, the recording area is Is opaque (whitening, erasing)
Is done. Next, when only the display character portion of the recording area is heated and cooled in the temperature region T ₂ of FIG. 3 by a recording means such as a thermal head, only the display character portion is made transparent, and the contrast between the opaque portion and the transparent portion allows visual observation. It becomes possible to read the recorded information of. If the opacity (whitening) temperature T ₁ is low, the preservability is lowered, and if the temperature range of T ₁ is narrow,
The temperature range of opacity (whitening) is narrowed and the erasability is reduced. On the other hand, if T ₂ is too high, the damage to the recording material at the time of printing or erasing becomes large, and the durability deteriorates. Therefore, T ₁ is 80 to 150 ° C and T ₂ is 120 to 170 ° C.
Is desirable. However, T ₁ and T ₂ do not substantially overlap.

In the present invention, as the polymeric resin base material constituting the recording layer, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinyl acetate. -Alcohol copolymer, other vinyl acetate compound, vinyl chloride copolymer, polyvinylidene chloride, vinylidene chloride copolymer, pyriester, polyamide, polystyrene, polymethyl (meth) acrylate, or a copolymer thereof preferable.

Examples of the combination of the crystalline low molecular weight compound to be dispersed in the resin base material include a combination of a fatty acid ester composed of a fatty acid and cholesterol and an aliphatic dibasic acid, and a typical fatty acid ester composed of a fatty acid and cholesterol. Is cholesterol caprate, cholesterol laurate, cholesterol myristate, cholesterol palmitate, cholesterol stearate,
Examples thereof include cholesterol behenate and cholesterol lignocerate. As a typical aliphatic dibasic acid,
Adipic acid, suberic acid, azelaic acid, sebacic acid,
Aliphatic dibasic acids such as dodecane diacid and tetradecane diacid may be mentioned.

By changing the mixing ratio of the crystalline low molecular weight compound dispersed in the resin base material, the temperature at which the resin is made transparent and opaque (cloudy) can be freely changed. This mixing ratio is appropriately set in consideration of the performance of the printing / erasing device, the sharpness of the printing contrast, and the like. Furthermore, the combination of the crystalline low molecular weight compound dispersed in the resin base material is (1) in the case of two kinds other than the above-mentioned combination.
In the case of the formula, the formula (2) and three or more kinds, if the formulas (4) and (5) are satisfied at the same time, there is no problem even with other crystalline low molecular weight compounds.

As the protective film, polyethylene terephthalate, polyetherimide, polyetheretherketone, polysulfone, polyphenylene sulfide,
A resin having high heat resistance such as polyacrylate, polyether sulfone, polycarbonate, polyethylene naphthalate, polyimide, acrylic resin is preferable.

The reflective layer is preferably a vapor-deposited layer of aluminum, tin, or the like, or a paint mixed with foil or aluminum grease.

[0035]

【Example】

<< Example 1 >> A magnetic paint was previously used as a magnetic recording layer.
Aluminum was vapor-deposited as a reflection layer on the surface of a 188 μm-thick polyethylene terephthalate resin film applied to a thickness of 0 μm, and a recording layer was coated thereon to a thickness of 10 μm. As a polymer resin base material and a crystalline low molecular weight compound constituting the heat-sensitive recording layer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer 60 parts by weight cholesterol stearate [C ₁₇ H ₃₅ CO 2 C 25 H ₄₇ ] 25 parts by weight adipic acid [ 15 parts by weight of HO _{2 C} (CH ₂ ) ₄ CO _{2 H} ] was dissolved in tetrahydrofuran, applied on the aluminum vapor deposition layer, and dried by heating to a thickness of 10 μm. A polyethylene terephthalate resin protective film having a thickness of 2 μm was attached thereon. By printing on the heat-sensitive recording layer side of the card substrate thus obtained, a printing layer having a visible recording display window as an opening was formed. Further, after providing a protective printing layer on the magnetic recording layer side, it was punched out into a card mold to produce a card of the present invention.

Example 2 A card was prepared in the same manner as in Example 1, except that the adipic acid of Example 1 was changed to suberic acid [HO _{2 C} (CH ₂ ) ₆ CO _2H ].

Example 3 A card was prepared in the same manner as in Example 1 except that the adipic acid of Example 1 was changed to sebacic acid [HO _{2 C} (CH ₂ ) ₈ CO _2H ]. << Example 4 >> The adipic acid of Example 1 was replaced with dodecanoic acid [HO _2C
A card was produced in the same manner as in Example 1 except that (CH ₂ ) _10C O ₂ H] was used.

Example 5 A card was prepared in the same manner as in Example 1 except that the adipic acid of Example 1 was changed to tetradecanoic acid [HO _{2 C} (CH ₂ ) _12C O ₂ H].

Example 6 A card was prepared in the same manner as in Example 1 except that hexadecanoic acid [HO _{2 C} (CH ₂ ) _14C O ₂ H] was used instead of adipic acid in Example 1.

Comparative Example 1 A card was prepared in the same manner as in Example 1 except that the adipic acid of Example 1 was changed to octadecane diacid [HO _2C (CH ₂ ) _16C O ₂ H].

Comparative Example 2 A card was prepared in the same manner as in Example 1 except that adipic acid in Example 1 was changed to eicosane diacid [HO _{2 C} (CH ₂ ) _18C O ₂ H].

Comparative Example 3 A card was prepared in the same manner as in Example 1 except that the adipic acid of Example 1 was changed to cholesterol palmitate [C ₁₅ H ₃₁ CO _2C25 H ₄₇ ].

Comparative Example 4 A vinyl chloride-vinyl acetate-vinyl alcohol copolymer 60 parts by weight behenic acid [C _{21 H43} CO _2H ] 25 parts by weight Dodecane diacid [HO _{2 C} (CH ₂ ) _10C O ₂ H] 15 parts by weight For these examples and comparative examples, 50 ° C to 150 ° C
Was heated at 1 ° C. intervals and cooled from that temperature, and the reflection density at each temperature was measured with a Macbeth densitometer RD-914 to determine the clearing temperature range and the clouding temperature range. The measured value is 0.
5 or less is an opaque state (white turbid state), and 1.0 or more is a transparent state, and the minimum reflection density at the opaque (whitening) temperature range, the clearing temperature range and the opaque (white turbidity) and the maximum reflection density at the transparent I asked. The results are shown in Table 1 together with the compatibility index of each crystalline low molecular compound.

[0044]

[Table 1]

As can be seen from Table 1, the difference in compatibility index between the two crystalline low molecular weight compounds is larger than 0.1, and
Examples 1 to 1 satisfying the relationship of T _g2 <T _c1 ≦ T _c2 <T _g1
Example 6 shows good negative recording characteristics. On the other hand, Comparative Examples 1 to 3 which do not satisfy the above conditions cannot record, and Comparative Example 4 cannot record positive type and negative type.

Although two types of crystalline low molecular weight compounds are used in the above examples, three or more types of crystalline low molecular weight compounds can be used.

In this case, the molar fraction of each of the three or more types of crystalline low molecular weight compounds dispersed in the polymer resin matrix is m _x (x = 1, 2, 3, ...), 3 When the compatibility index of one or more crystalline low molecular weight compounds with each polymer resin matrix is S _x , the following formulas (4) and (5) may be simultaneously satisfied.

[0048]

[Number 18] _{| m y S y -m z S} z |> 0.1 (4)

[0049]

Equation 19 _{T g2 <T c1 ≦ T c2} <T g1 (5) However, m _y S _y and m _z S _z is m _x S for crystalline low molecular compound which m _x S _x each having a maximum value _x
And the compatibility index S is as described above, and T _g1 and T _g2 are respectively the heating of the reversible thermosensitive material composition to the first temperature region T ₁ and the second temperature region T ₂ , followed by cooling. The glass transition temperature, T _c1 and T _c2 of the polymer resin base material at this time are the values when the reversible thermosensitive material composition is heated to the first temperature region T ₁ and the second temperature region T ₂ and then cooled, respectively. It is the extrapolation crystallization start temperature of the compound having the lowest crystallization temperature among the crystalline low molecular weight compounds dispersed in the polymer resin matrix.

[0050]

As described above, when the reversible thermosensitive recording material composition according to the present invention is used, negative type recording contrary to the conventional one can be performed, and therefore the visibility is improved and the paper-like prepaid card is improved. Can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a differential thermal analysis result of a thermal recording material composition of the present invention.

FIG. 2 is a diagram showing the results of differential thermal analysis of the crystalline low molecular weight compound used in the heat-sensitive recording material composition of the present invention.

FIG. 3 is a diagram showing static characteristics of the heat-sensitive recording material composition of the present invention.

FIG. 4 is a perspective view of a card using the thermal recording material composition of the present invention.

FIG. 5 is a cross-sectional view of a card using the heat-sensitive recording material composition of the present invention.

[Explanation of symbols]

 1 Card Base Material 2 Reflective Layer 3 Thermal Recording Layer 4 Protective Layer 5 Printing Layer 6 Visible Recording Display Area 7 Magnetic Recording Layer 8 Protective Printing Layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G06K 19/00 B

Claims (5)

[Claims] 1. Two kinds of crystalline low molecular weight compounds are mixed and dispersed in a polymer resin base material, and when cooled from a _first temperature region T ₁ and when a second temperature region T ₂ higher than T ₁ is used. In a reversible thermosensitive recording material composition in which the light transmittance changes when cooled from above, the two types of crystalline low molecular weight compounds simultaneously satisfy the following formulas (1) and (2): Thermal recording material composition; [Formula 1] | S ₁ −S ₂ |> 0.1 (1) [ _Formula 2] T _g2 <T _c1 ≦ T _c2 <T _g1 (2) where S ₁ and S ₂ are The compatibility index (S) of each of the two types of crystalline low molecular weight compounds with the polymer resin matrix is represented by the compatibility index S, which is a crystalline low molecular weight compound dispersed in the polymer resin matrix. the necessary amount of heat required to melt all crystals [Delta] H _m, to melt the same crystalline low molecular compound alone in the same amount When the amount was defined as [Delta] H _M, is defined by the following formula [Number 3] _{S = 1- (ΔH m / ΔH} M) (3), T g1 and T _g2 are respectively the reversible thermosensitive material composition first Is a glass transition temperature of the polymer resin matrix when heated to a temperature region T ₁ and a second temperature region T ₂ and then cooled, where T _c1 and T _c2 respectively represent the reversible thermosensitive material composition. Of the crystalline low molecular weight compound dispersed in the polymer resin matrix when heated to the first temperature region T ₁ and the second temperature region T ₂ and then cooled, the compound showing the lowest crystallization temperature Extrapolation crystallization start temperature. 2. A crystalline resin matrix containing three or more kinds of crystalline low-molecular compounds mixed and dispersed, when cooled from a _first temperature region T ₁ and when a second temperature region T higher than T ₁ is used. _In the reversible thermosensitive recording material composition in which the light transmittance changes when cooled from _{2, the} molar fraction of each of the three or more crystalline low molecular weight compounds dispersed in the polymer resin matrix the _{m x (x = 1,2,3 ···)} , when the compatibility index to each of the polymer resin matrix of the three or more crystalline low molecular compound was S _x, the following formula ( 4) and (5) a reversible thermosensitive recording material composition and satisfies the same time; Equation 4] _{| m y S y -m z S} z |> 0.1 (4) Equation 5] T _g2 <T _c1 ≦ T _c2 <T _g1 (5) where m _y S _y and m _z S _z are low crystalline with m _x S _x having the maximum value, respectively. M _x S _x for molecular compounds
The compatibility index S is ΔH _m , which is the amount of heat required to melt all the crystals of the crystalline low molecular weight compound dispersed in the polymer resin matrix, and the same amount of the same crystalline low molecular weight compound alone. When the amount of heat necessary for melting is ΔH _M , it is defined by the following equation: S = 1− (ΔH _m / ΔH _M ) (6), and T _g1 and T _g2 are the reversible thermosensitive properties, respectively. The glass transition temperature of the polymer resin base material when the material composition is heated to the first temperature region T ₁ and the second temperature region T ₂ and then cooled, where T _c1 and T _c2 are the reversible temperatures, respectively. The lowest crystal of the crystalline low molecular weight compound dispersed in the polymer resin base material when the heat-sensitive material composition is heated to the first temperature region T ₁ and the second temperature region T ₂ and then cooled It is the extrapolation crystallization start temperature of the compound showing the crystallization temperature. 3. The reversible thermosensitive material composition becomes opaque when cooled from the first temperature region T ₁ and becomes transparent when cooled from the second temperature region T _2. The reversible thermosensitive recording material composition according to 1 or 2. 4. A magnetic recording layer and a magnetic recording layer on a resin substrate.
5. A prepaid card provided with a heat-sensitive recording layer comprising the reversible heat-sensitive recording material composition described in any one of 1 to 3 above. 5. The magnetic recording layer is provided on one surface of the resin base material, and the thermosensitive recording layer is provided on the other surface of the resin substrate via a reflective layer. The thermosensitive recording layer is provided on the thermosensitive recording layer. The prepaid card according to claim 4, wherein the protective layer is provided with a printing layer having an opening on the protective layer.