JPS63130380A - Reversible thermal recording material - Google Patents

Abstract

PURPOSE:To enable formation of an image with high contrast and facilitate temperature control, by using a higher fatty acid having a specified number of carbon atoms and at least one of a higher fatty acid or a higher alcohol which have specified numbers of carbon atoms, as an organic low molecular weight substances to be dispersed in a resin matrix. CONSTITUTION:A thermal recording layer is provided which comprises a resin matrix and an organic low molecular weight substance dispersed in the resin matrix as main constituents, and has a transparency reversibly changed depending on temperature. A higher fatty acid having at least 16 carbon atoms and at least one of (a) a higher fatty acid having 10-15 carbon atoms and (b) a higher alcohol having at least 12 carbon atoms are used in a weight ratio of 95:5-20:80, as the organic low molecular weight substance. The mixture shows an eutectic phenomenon when being heated. As a result, the transparentization temperature range of the thermal recording layer is changed or enlarged according to variations in the mixing ratio, whereby temperature control in transparentization of a recording material is facilitated, and it is possible to obtain a sufficient degree of transparentization even when the proportion of the organic low molecular weight substance is set to be high.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a reversible heat-sensitive recording material that forms and erases images by utilizing reversible changes in transparency of a heat-sensitive layer depending on temperature.

Prior art Japanese Patent Publication Nos. 54-119377 and 55-154198
In this issue, a reversible heat-sensitive recording material is proposed which has a heat-sensitive layer in which a low-molecular-weight organic substance such as a higher fatty acid is dispersed in a resin base material such as a vinyl chloride resin. Image formation and erasing using this type of recording material utilizes the reversible change in transparency of the heat-sensitive layer due to temperature.

When these recording materials are actually made transparent or opaque by heating, if the amount of organic low-molecular substances sealed in the resin base material is small, the concentration of the opaque area (white part) will be low, and the organic low molecular weight on the resin base material will be low. When the number of #AIJi molecules is high, the density of the opaque area (white area) is high, but the degree of transparency is low, and therefore optical spectral contrast cannot be obtained. Furthermore, since the temperature range at which the opaque area becomes transparent is narrow at about 2 to 4 degrees Celsius, it is possible to make at least a partially opaque recording material transparent, or to create a colorless (transparent) image on a completely opaque recording material. Besides forming, temperature control is difficult.

Purpose An object of the present invention is to provide a reversible thermosensitive recording material that can form a high-contrast iihlm and that can be easily controlled in temperature.

composition The reversible thermosensitive recording material of the present invention has a resin base material.

In a reversible thermosensitive recording material having a heat-sensitive layer whose transparency changes reversibly depending on the temperature, the thermosensitive layer is mainly composed of an organic low-molecular substance and is dispersed in the resin matrix, wherein the organic low-molecular substance is Higher fatty acids with carbon number 16J2i, (8) higher fatty acids with carbon number 10 or more and 15 or less, and (b
) It is characterized in that at least one yuzu of a cylinder number alcohol having 12 or more carbon atoms is used in a stacking ratio of 95:5 to 20:80.

The recording (and erasing) principle of the recording material of the present invention utilizes the change in transparency of the heat-sensitive layer (or sheet) depending on the temperature, and this will be explained with reference to the drawings. In FIG. 1, a heat-sensitive material 1m consisting mainly of a resin base material and an organic low-molecular substance in the resin base material is in a cloudy, opaque state at room temperature below T, for example. When this is heated to a temperature between TI and T, it becomes transparent and in this state Ill. It remains transparent even after returning to room temperature below. Further heating to a temperature of T1 or higher results in a translucent state intermediate between maximum transparency and maximum opacity. Next, when this temperature is lowered, the liquid returns to its initial cloudy, opaque state without becoming transparent. In addition, this opaque state is T. When the material is heated to a temperature between -T1 and then cooled to room temperature, that is, a temperature of T0 or higher, it can assume a state between transparent and opaque. Also, if the above-mentioned material that becomes transparent at room temperature is heated again to a temperature of 18 or higher and returned to room temperature, it will return to its white, cloudy, opaque state. That is, at g temperature, it can take both opaque and transparent forms and an intermediate state between them.

Therefore, the entire heat-sensitive layer is heated to a temperature of T1 to Tzl using a heat roll, and then cooled to room temperature below pPlt&,To to make it transparent.
Then, by heating this on T and Q in a painting style with a thermal head or the like to make the area opaque, a white image is formed on this layer. On the other hand, T after heating the entire partially opaque heat-sensitive layer to a temperature of T1 or higher. After returning the temperature to room temperature as shown below to make the entire area cloudy and opaque, use a thermal head or the like to heat the area to a temperature between T and -T to make that part transparent, and a transparent image will be formed against a white background. . Note that the above-described recording and erasing operations on the heat-sensitive layer can be repeated 104 times or more.

Furthermore, the organic low-molecular substance used in the heat-sensitive layer has a carbon number of 1.
When a higher fatty acid of 6 or more and at least one starch of the compounds (a) and (b) above are mixed and used in a specific ratio, this mixture causes a eutectic phenomenon when heated, resulting in a change in the mixing ratio. The transparentization temperature axis 'r, ~T, of the heat-sensitive layer expands, making it easier to control the temperature when making the recording material transparent as described above, and increasing the ratio of the organic low-molecular substance to the resin base material. It has been found that even when the amount is increased, a high degree of optical transparency can be obtained and the contrast can also be improved.

The heat-sensitive recording material of the present invention is generally produced by coating (or (Impregnation) Drying, or kneading the above ingredients while heating, and coating this on the support.

Alternatively, it can be made by molding into a film or sheet. The heat-sensitive layer forming liquid used in this process usually consists of dissolving both the resin base material and organic low-molecular substance in a solvent, or
Alternatively, it can be obtained by pulverizing or dispersing an organic low-molecular substance (insoluble in the solvent of the base material) in a resin base material bath liquid using various methods. As a solvent, tetrahydrofurano, methyl ethyl ketone,
Methylindithylketone, chloroform, carbon tetrachloride,
Examples include ethanol, toluene, and benzene. It should be noted that in the heat-sensitive layer obtained when a bath liquid is used as well as when a dispersion liquid is used, the organic low-molecular substance precipitates as fine particles and exists in a dispersed state.

The resin base material used for the heat-sensitive layer forms a layer in which a low-molecular-weight organic substance is uniformly dispersed, and is a material that influences the transparency at maximum transparency. For this reason, the base material has good transparency, mechanical stability, and 4T (preferably JL), which has good film formability.2 Such resins include polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, and chlorinated vinyl. Vinyl chloride-based copolymers such as vinyl-vinegar winter, vinyl-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride acrylate copolymer; polyvinyl chloride, 9-dene, chloride Examples include vinylidene chloride copolymers such as vinylidene-vinyl chloride copolymers and vinylidene chloride-acrylonitrile copolymers; polyesters; polyamides; polyacrylates or polymethacrylates or acrylate-methacrylate copolymers, silicone resins, and the like.

These may be used alone or in combination of two or more.

On the other hand, the organic low-molecular substances include higher fatty acids having 16 or more carbon atoms and at least 18I of the compounds (a) and (b) above.
A mixture of Specific examples of higher fatty acids having 16 or more carbon atoms include palmitic acid, margaric acid,
Stearic acid, nonadecanoic acid, eicosane acid, heneicosanoic acid, hehenomeshi, lignocerinth, pentacosane (, cerotic acid, heptacanoic acid, montanic acid, nonacosanoic acid, melisic acid, 2-hexadecenoic acid, trans-
3-hexadecene ^l, 2-hebutadecene χ, trans-2-octadenoic acid, cis-2-octadecanoic acid,
trans-4-octadecenoic acid, cis-6-octadecenoic acid, elaidine,), trans-seninjo, trans-bond in, eluka w, plasic acid, ceracolein catfish, trans-ceracolein, trans-8, trans- 10
Examples include -octadecadiene, rhinoelaidic acid, a-eleostearic acid, -1-eleostearic acid, sinido-eleostearic acid, 12.20-7-eicosadienoic acid, and the like. These starches can be used alone or in combination.

Specific examples of compound (a) include carric acid, Kundecanoic acid, Lauric acid, Tridecanoic acid, Myristic acid, Pentadecanoic acid, 12-methyltridecanoic acid, 2-methyltetradecanoic acid, 13-methyltetradecanoic acid, lO-undecanoic acid. , etc.

Specific examples of compound (b) include lauryl alcohol, tridecane 1-ol, myristyl alcohol, pentadecane 1-ol, cetyl alcohol, and heptadecan 1-ol.

Stearyl alcohol, nonadeca/l-ol, araquinyl alcohol, heneicosanol-1, docosanol-1, tricosanol-1, tetracosanol-1,
Pentacosanol-1, Hexacosanol-1, Heptacosanol-1, Octacosanol-1, Hexadecane-2-ol, Heptadecan-2-ol, Octadecane-2
-ol, nonadecane 2-ol, eicosan 2-ol, 2-hexadecenol-1 (cis), 2-hebutadecenol-1 (cjs), 2-ophtadecenol-'1 (cis), 2-ophtadecenol-1
(trans), elaidin alcohol, eleostearyl alcohol (β), and the like.

The mixing ratio of the higher fatty acid having 16 or more carbon atoms used as the organic low-molecular substance and at least one of the compounds (eL) and (b) is in the range of 95:5 to 20:80 (weight t). If the temperature is outside this range, the temperature range for transparency will not be widened.

Also, what is the ratio of organic low-molecular substances and resin base material in Heat Sensitive 1-? i amount ratio l:0.5-1:16, especially 1:0.5-1
: 3 degree is preferable. When the ratio of the base material is less than this,
It becomes difficult to form a film that retains the organic low-molecular substance in the base material, and on the other hand, if the amount exceeds this range, it becomes difficult to make it opaque because the amount of the organic low-molecular substance is small.

The present invention will be explained in more detail below with reference to Examples. All parts are by weight.

Example 1 Behenic acid 95 parts Stearyl alcohol 5 parts Vinyl chloride-vinegar "Vinyl copolymer 200 parts (UOO
Gvyi-in) Tetrahydrofuran 1000
A solution consisting of 75μ? A reversible heat-sensitive recording material was prepared by applying the mixture onto a #3 polyester film using a wire nozzle and drying it by heating to form a heat-sensitive layer having a thickness of 15 parts.

Example 2 A reversible thermosensitive recording material was prepared in the same manner as in Example 1, except that 95 parts of behenic acid was changed to 80 parts, and 5 parts of stearyl alcohol was changed to 20 parts.

Example 3 A reversible heat-sensitive recording material was prepared in the same manner as in Example 1, except that 95 parts of behenic acid was changed to 30 parts, and 5 parts of stearyl alcohol was changed to 70 parts.

Comparative Example 1 A reversible thermosensitive recording material was prepared in the same manner as in 4M' Example 1, except that 98 parts of behenic acid 95 f'h and 2 parts of 5 parts of stearyl alcohol were used.

Comparative Example 2 A reversible thermosensitive recording material was prepared in the same manner as in Example 1, except that 95 parts of behenic acid was changed to 10 parts and 5 parts of tearyl alcohol was changed to 90 parts.

Examples 4 to 13 Reversible thermosensitive recording materials were prepared in the same manner as in Example 2, except that the same amount of the compound shown in the table was used in place of stearyl alcohol.

Example 14 A reversible heat-sensitive recording material was prepared in the same manner as in Example 2, except that the vinyl chloride-vinyl copolymer was used as 100 cells.

Comparative Example 3 A reversible heat-sensitive recording material was prepared in the same manner as in Example 1 except that 5 parts of stearyl alcohol was removed and 95 parts of behenic acid was changed to 100 parts. Comparative Example 4 95 parts of behenic acid was removed and stearyl A reversible thermosensitive recording material was prepared in the same manner as in Example 1 except that 100 parts of alcohol was changed from 5 parts.

Comparative Example 5 A reversible #V thermal recording material was prepared in the same manner as in Comparative Example 3 using 100 parts of a vinyl chloride-vinyl acetate combination.

All of the heat-sensitive recording materials obtained as described above exhibited an opaque white color. After heating each recording material from 50°C to 80°C in 1°C increments, it was allowed to cool to room temperature, and this was turned into a black color. 1 paper, and the reflected magnetism was measured using a Macbeth magnetometer D514. At this time, the temperature at which the reflection degree exceeded 1.0 was defined as the transparency temperature, and its range (width) was shown.

Also, the minimum value of this density is taken as the density of the opaque part (white part),
On the other hand, the maximum value was taken as the transparent part magnetism. The result is as shown below.

(Left below) Effects As described above, the reversible heat-sensitive recording material of the present invention contains at least one of the higher fats having 16 or more carbon atoms and the above-mentioned compounds (a) and (b) as organic low-molecular substances in the heat-sensitive layer. Since a mixture of 1 type and 1 type is used in a specific ratio, it is possible to improve the contrast, and as a result, the transparentizing temperature range is widened. It has the advantage of being easy.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the principle of image formation and erasing in the heat-sensitive layer of the recording material of the present invention. Patent Applicant Ricoh Co., Ltd. - Figure 1 Procedural Amendment January 21, 1988 Director General of the Patent Office Kunio Ogawa 1, Indication of Case 1985 Patent Application No. 278102 2, Name of Invention Reversible Thermal Sensitivity Recording material 3, Relationship with the case of the person making the amendment Patent applicant Rico Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo (b74) - Representative Hama 1) Hiro 4, Agent Kojimachi, Chiyoda-ku, Tokyo 4-5-5 (102) 5, Target of amendment -11, -1, 6, Contents of amendment (1) Page 3 of the specification, line 8, after "16 or more", ", preferably 16 to 30, and Preferably 16 to 24''. (2) Add ``, preferably 14 to 24'' after ``12 or more'' on page 3, line 11. (3) Page 10, line 13 rl: rl 3J
: Corrected to 5J. that's all

Claims (1)

[Claims] 1. In a reversible thermosensitive recording material having a thermosensitive layer whose transparency changes reversibly depending on temperature, the main components being a resin matrix and an organic low-molecular substance dispersed in the resin matrix. , a higher fatty acid having 16 or more carbon atoms as the organic low molecular substance and at least one of (a) a higher fatty acid having 10 to 15 carbon atoms and (b) a higher alcohol having 12 or more carbon atoms in a ratio of 95:5 to A reversible thermosensitive recording material characterized in that it is used at a weight ratio of 20:80.