JPH04358879A - Reversible thermal recording material - Google Patents

Abstract

PURPOSE:To widen the a transparency-change temperature range by using fatty acid, higher fatty acid and aliphatic saturated dicarboxylic acid, melting points of which are kept within specific ranges, as low molecular compounds in a recording material, in which an organic low molecular compound is dispersed into a high molecular resin base material and the base material is changed reversibly into transparency and opacity by heat. CONSTITUTION:A reflecting layer 2, a recording material layer 3, a protective layer 4 and a printed layer 5 for forming a visible recording display window 6 are laminated on a synthetic-resin base material sheet 1, and a magnetic recording layer 7 is formed on the rear. Fatty acid A, the melting point of which is lower than 60 deg.C, higher fatty acid or higher ketone B having the melting point of 60-100 deg.C and aliphatic saturated dicarboxylic acid C having the melting point of 100 deg.C or higher are dispersed into the high molecular resin base material of the recording material layer 3 respectively. A temperature range changed into transparency can be altered by varying the mixing ratio of these A, B, C, B:C=90:10-50:50, and (B+C):A=90:10-60:40 are favorable as the mixing ratio of each component, and 10-80 pts.wt. is preferable to the 100 pts.wt. base material as the total amount of A, B and C.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material capable of repeatedly displaying and erasing visible images.

0002

BACKGROUND OF THE INVENTION As a reversible thermosensitive recording material, one in which an organic low molecular compound is mixed and dispersed in a polymeric resin base material has been proposed (Japanese Patent Application Laid-Open No. 154198/1983). This material becomes transparent when cooled from a specific temperature range T1 to room temperature, and becomes cloudy when cooled from a temperature range T2 higher than T1 to room temperature, so this material can be used to reversibly convert visible images. can be printed and erased.

0003

[Problem to be solved by the invention] However, this material has a very narrow temperature range T1 in which it becomes transparent.
There was a problem in that temperature control for printing and erasing was very difficult.

0004

[Means for Solving the Problems] The present invention solves the above-mentioned problems, and uses at least one of: A) a fatty acid having a melting point of less than 60°C as an organic low-molecular compound to be dispersed in a polymeric resin base material; 1 type, B) at least one type of higher fatty acid or higher ketone having a melting point of 60°C or higher and lower than 100°C; and C) at least one type of aliphatic saturated dicarboxylic acid having a melting point of 100°C or higher. .

The present invention will be explained below with reference to the drawings. FIG. 1 is a front view showing an example of a card using the recording material of the present invention, and FIG. 2 is a Z-Z sectional view thereof. The polymeric resin base material in the present invention may be any resin that is transparent and has good film-forming properties, such as polyvinyl chloride, vinyl chloride copolymers such as vinyl chloride-vinyl acetate copolymers, polyvinylidene chloride,
Vinylidene chloride copolymer, polyester, polyamide,
Preferred are polystyrene, polymethyl (meth)acrylate, or copolymers thereof.

The organic low-molecular compounds to be dispersed in these polymeric resin base materials include: A) at least one fatty acid with a melting point of less than 60°C; B) higher fatty acids or higher ketones with a melting point of 60°C or more and less than 100°C. and C) at least one aliphatic saturated dicarboxylic acid having a melting point of 100° C. or higher. That is, since the phenomenon of transparency of these recording materials occurs near the melting point of the organic low-molecular compound,
Focusing on compounds with melting points near the desired clearing temperature (generally 60 to 100 degrees Celsius), we combine low-molecular compounds with melting points lower than that range and low-molecular compounds with higher melting points, and the eutectic phenomenon is By using this method, a recording material having a wide range of transparentization temperatures can be obtained. It has been found that the above-mentioned compounds A, B, and C are excellent as compounds having respective melting point ranges. By changing the mixing ratio of these organic low-molecular compounds, the temperature range T1 at which they become transparent can be freely changed, and the mixing ratio is set by considering the performance of the printing and erasing equipment and the film-forming properties of the recording material. .

[0007] As component A, fatty acids having a melting point of less than 60°C include caproic acid (melting point -3°C) and caprylic acid (17°C).
, saturated fatty acids such as capric acid (32°C), pelargonic acid (13°C), lauric acid (44°C), myristic acid (54°C), oleic acid (4°C), erucic acid (34°C),
15-tetracosenoic acid (39℃), tallyric acid (51℃)
, 11-octadecynoic acid (46°C) and other unsaturated fatty acids. In addition, the melting point of component B is 60°C or higher, 100°C
Examples of higher fatty acids and higher ketones below ℃ are palmitic acid (63℃), docosanoic acid (80℃), and melisic acid (9℃).
4℃), stearic acid (69℃), arachidic acid (75℃), stearic acid (69℃),
°C), cerotic acid (88 °C), seroplastic acid (98 °C)
higher fatty acids such as 11-heneicosanone (64 °C),
), 12-tricosanone (69°C), 14-heptacosanone (78°C), 16-hentriacontanone (83°C)
Examples include ketones such as ℃).

[0008] As the aliphatic saturated dicarboxylic acid having a melting point of 100°C or higher as component C, azelaic acid (107°C) is used.
, sebacic acid (133℃), undecanedioic acid (111℃)
), dodecanedioic acid (128°C), tridecanedioic acid (11
3°C), tetradecanedioic acid (126°C), pentadecanedioic acid (114°C), hexadecanedioic acid (124°C), heptadecanedioic acid (118°C), octadecanedioic acid (12
4℃), nonadecanedioic acid (119℃), eicosanedioic acid (123℃), docosanedioic acid (123℃), tricosanedioic acid (127℃), hexacosanedioic acid (123℃), tetratriacontanedioic acid ( 123℃).

The mixing ratio of each component is as follows: the ratio of B component to C component B:C is 90:10 to 50:50, and the ratio of A component to the total amount of both B and C components (B+C):A is 90: 10
It is preferable that the ratio is in the range of 60:40. A particularly preferable mixing ratio is B:C of 80:20 to 60:40 (B+C).
:A is in the range of 85:15 to 65:35. The total amount of components A, B and C is 1 part by weight per 100 parts by weight of the resin base material.
The amount is 0 to 80, preferably 30 to 70 parts by weight.

[0010] When this recording material is heated to a temperature T1 using a heating means such as a thermal head, a heating stamp, or a heating roll, it becomes transparent. Next, this transparent recording material is heated to a temperature higher than T1 using a thermal head, heated stamp, etc.
2. If the area is heated locally, only the heated area becomes opaque (cloudy) and a visible image can be displayed. To erase the image, it is sufficient to heat it again to the temperature range T1. If the width of this temperature range T1 for transparency is less than 5℃, it is difficult to control the temperature of heating means such as a thermal head, so it is difficult to obtain a stable transparent state, and if it is 60℃ or higher, the printing temperature T2 becomes too high. However, according to the present invention, a temperature range of, for example, 30 or more can be easily obtained.

FIGS. 1 and 2 show a card which is an example of the use of the recording material of the present invention, in which a reflective layer 2 is formed on the surface of a synthetic resin base sheet 1 such as polyethylene terephthalate (PET). A recording material layer 3, a protective layer 4, and a printing layer 5 for forming a visible recording display window 6 are laminated. Further, a magnetic recording layer 7 and a protective layer 8 are provided on the back surface. The reflective layer 2 is for making it easier to see the image formed on the recording material layer 3, and is preferably a vapor-deposited layer or foil of aluminum, tin, or the like, or a paint layer mixed with metal powder. The protective layer 4 prevents thermal deterioration of the recording material layer 3 and is made of PET, polyetherimide, polyetheretherketone, polysulfone, polyphenylene sulfide, polyarylate, polyethersulfone, polycarbonate, polyethylene naphthalate, polyimide. A film or coating made of a transparent resin with high heat resistance such as acrylic resin can be used.

[0012] This card can be used, for example, as a prepaid card for admission, shopping, rental, etc.
By visually displaying the amount spent and the remaining amount on the recording material layer 3 together with the magnetic recording each time the device is used, it is possible to always know the exact remaining amount.

[0013]

EXAMPLE Aluminum was vapor-deposited as a reflective layer on the surface of a 188 μm thick PET sheet on which a 10 μm thick magnetic recording layer had been previously formed on the back surface. On top of that, vinyl chloride-
Vinyl acetate copolymer (Nissin Chemical Co., Ltd. MRP-TS) 10
0 parts by weight, oleic acid (melting point 4°C) as component A of the organic low molecular compound, docosanoic acid (melting point 8°C) as component B.
0°C), a recording material containing 1,12-tetradecanedioic acid (melting point 126°C) as component C in the amount shown in Table 1 was dissolved in tetrahydrofuran and coated, and dried to a thickness of 10 μm.
A recording material layer was formed. On top of that, a PET film with a thickness of 2 μm was pasted as a protective layer, and further printed to form a visible recording display window, while a protective layer was provided on the magnetic recording layer on the back side, and a card shape was punched out. .

[0014] Then, each of the obtained cards was heated at 50°C for 1
The recording material was heated to 20° C. at 1° C. intervals, and the reflection density of the recording material at each temperature was measured using a Macbeth reflection densitometer RD-914. The transparent temperature range T1 and its temperature range were determined, with a measured value of 0.5 or less as an opaque state and a measured value of 1.0 or more as a transparent state. The results are shown in Table 1. In Table 1, No.
1 is an example of the present invention, No. 1 is an example of the present invention; 2 to 4 are comparative examples.

[0015]

[Table 1]

No. 1 using the recording material of the present invention. It can be seen that in No. 1, the transparent temperature T1 has a wide temperature range, and a stable transparent state can be obtained even if the heating temperature fluctuates somewhat. On the other hand, No. 3, which does not use the three components in combination. 2 to 4 have a narrower temperature range than that. Also No. The recording material layer of the card No. 1 was heated to 85° C. and then cooled to room temperature to make it transparent, and characters were printed using a thermal head at a printing energy of 1.3 Joules/cm 2 . When these were heated to a temperature within the transparency temperature range, the characters were erased, and even if this process was repeated 1000 times, the same visibility was obtained.

[0017]

Effects of the Invention The recording material of the present invention has a wide transparency temperature range, and therefore maintains a stable transparent state even when the heating temperature fluctuates. Suitable for displaying images.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a card using the recording material of the present invention.

FIG. 2 is a sectional view taken along the Z-Z line in FIG. 1;

[Explanation of symbols]

1 Card base material 2 Reflection layer 3 Recording material layer 4 Protective layer

Claims (1)

[Claims] Claim 1: In a reversible thermosensitive recording material which is made by dispersing an organic low molecular compound in a polymeric resin base material and which changes reversibly between a transparent state and an opaque state depending on the temperature, as the low molecular compound A) B) at least one type of higher fatty acid or higher ketone with a melting point of 60°C or higher and lower than 100°C; and C) at least one aliphatic saturated dicarboxylic acid with a melting point of 100°C or higher. A reversible heat-sensitive recording material characterized by the combination of seeds.