JPH10329429A - Thermal transfer ribbon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply visualize secret information at a receiver side by forming a thermal transfer layer provided on a base material surface of a thermal transfer ribbon of heat melt wax and/or thermoplastic resin containing temperature indicating agent containing microcapsulse, thereby printing the information in an invisible state. SOLUTION: The thermal transfer ribbon 1 for printing information on a sheet surface such as a postcard in a visible state by a thermal printer is executed with a thermal transfer layer 3 containing temperature indicating agent containing microcapsule in heat melt wax and/or thermoplastic resin on a surface of a base material 2. As the wax, paraffin wax or carnauba wax is suitably selected for use. As the thermoplastic resin, polyethylene or polyvinyl acetate is suitably selected for use. As the indicating agent, a thermochromic material for reversibly color developing, erasing or discoloring according to temperature change such as, for example, condensed aromatic ring substituted ethylene derivative or liquid crystal is given.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sense for printing information in a non-visible state on a sheet surface such as a postcard or a greeting card by a thermal printer using a temperature indicator which changes color, decolors or changes color by a change in temperature. It relates to a thermal transfer ribbon.

[0002]

2. Description of the Related Art With the development of word processors and personal computers, thermal transfer ribbons for thermal printers, which have become widespread, are made by adding a color dye or a pigment to a hot melt wax and / or a thermoplastic resin. The thermal transfer layer is applied to the substrate surface, and the thermal transfer layer is melted by a thermal head of a thermal printer, and the thermal transfer layer is partially transferred to the sheet surface to print information.

[0003]

The information printed on such a thermal transfer ribbon is colored by the color of the dye or pigment contained in the thermal transfer layer. Therefore, as a matter of course, it is not possible to use this to print, in an invisible state, secret information that is not desired to be seen by a person, for example, on a sheet surface such as a postcard or a greeting card. Alternatively, even if the printed portion of the sheet or the sheet base material is made the same color as that of the thermal transfer ribbon to make the information invisible, there is no means for the recipient to visualize the information.

[0004] Therefore, the present invention makes it possible to print confidential information that a user does not want to see on a sheet surface such as a postcard or a greeting card in an invisible state, so that the recipient can visualize the confidential information by simple means. An object is to provide a thermal transfer ribbon.

[0005]

Means for Solving the Problems Conventionally, a temperature indicator which realizes color development / decoloration or discoloration due to a temperature change has been put into practical use as a temperature indicator ink which is encapsulated in microcapsules and mixed with an ink vehicle. For example, it is printed on a temperature card, a mug, a T-shirt, or the like.

Accordingly, the present inventors have paid attention to the function of a temperature indicator that changes color, decolors, or changes color due to temperature change, particularly, a temperature indicator that is colorless at normal temperature but develops color by heating or cooling. Containing microcapsules encapsulating in hot melt wax and / or thermoplastic resin,
It has been found that the above object can be achieved by applying this to the substrate surface of the ribbon, and the present invention has been made.

That is, the heat-sensitive transfer ribbon of the present invention is a heat-sensitive transfer ribbon in which a heat-sensitive transfer layer is provided on a substrate surface, wherein the heat-sensitive transfer layer comprises a hot-melt wax containing microcapsules enclosing a temperature-inducing agent and / or Or thermoplastic resin,
From the main.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail based on preferred embodiments. FIG. 1 is a sectional view of the basic structure of the thermal transfer ribbon of the present invention. That is,
The heat-sensitive transfer ribbon 1 of the present invention is provided with a heat-sensitive transfer layer 3 made of hot-melt wax and / or a thermoplastic resin containing microcapsules containing a thermostat on the surface of a substrate 2.

As the substrate 2 of the thermal transfer ribbon of the present invention, a heat-resistant substrate conventionally used as a substrate of the thermal transfer ribbon is suitable, for example, having a film thickness of 20 μm or less, preferably 5 to 10 μm. Synthetic films such as polyimide, polyester, nylon, and polypropylene, and various processed papers.

Hereinafter, the hot-melt wax and / or thermoplastic resin, which are constituents of the heat-sensitive transfer layer 3, and the microcapsules enclosing the thermostat will be described in detail. Examples of the hot-melt wax include paraffin wax having a melting point of about 60 to 150 ° C., kaunabal wax, montan wax, petroleum wax, shellac wax, synthetic oxidized wax and its derivatives, or fatty acid ester wax, hydrogenated wax and the like. It can be suitably selected and suitably used. On the other hand, as the thermoplastic resin, the melting point or softening point is 60 to
Appropriately selected from polyethylene, polyvinyl acetate, polyvinyl chloride, polystyrene, polyacrylate and the like at about 150 ° C. can be suitably used. The hot-melt wax and the thermoplastic resin can be used alone or as a mixture, but most preferably a hot-melt wax having excellent transition properties is used.

The temperature indicator in the present invention is a thermochromic material which reversibly develops, discolors or discolors in response to a change in temperature. There are liquid crystals. Metamocolor is composed of an electron donating organic compound, an electron accepting compound, and a polar organic compound. The electron donating organic compound determines the color of the color,
For example, 3,6-dimethoxyfluoran (yellow), 3-cyclohexylamino-6-chlorofluoran (orange), 3
-Diethylamino-6-methyl-7-chlorofluoran (red), 3-diethylaminobenzfluoran, (peach)
Rhodamine B lactam (red), crystal violet lactone (blue), 3-diethylamino-7-dibenzylaminofluoran (green), 3-diethylamino-6-methyl-7-anilinofluoran (black) and the like. .

The electron-accepting compound determines the color density, and usually includes gallic acid propyl ester. Further, the polar organic compound determines the discoloration temperature, and examples thereof include higher alcohols such as n-octyl alcohol, n-densyl alcohol-lauryl alcohol, myristyl alcohol, cetyl alcohol, and stearyl alcohol. The discoloration temperature can be adjusted to about -40 to 40 by appropriately mixing these alcohols.
It can be arbitrarily selected within the range of 50 ° C.

The condensed aromatic ring-substituted ethylene derivative is, for example, a spiropyran-based compound such as di-α, β-naphthoisospiropyran, benzo-β-naphthoisospiropyran, 3-alkyl-di-β-naphthospiropyran. And anthrone-based compounds such as bianthrone, dixanthylene, and xanthylideneanthrone. Particularly preferred are spiropyran-based compounds, which include a cooling discoloration type and a heating discoloration type, which change from colorless to colored at a specific temperature, and change reversibly.

Further, the liquid crystal is preferably a cholesteric type liquid crystal which can be used as a thermochromic material, which is a derivative of cholesterol, which has a very small helical deformation energy in its molecular arrangement, and the helical pitch changes easily with temperature. This pitch change is considered as an optical color change. The discoloration temperature can be appropriately selected depending on the type and the mixing ratio.

When the temperature indicator is selected to be a specific color at room temperature, a printing portion formed by solid printing or copy-forgery-inhibited pattern printing in the same color as the specific color is applied to the base material surface of the sheet to be printed in advance. Alternatively, by selecting the same base color as the specific color, the printed confidential information becomes invisible. However, it is most preferable to select and prepare a temperature indicator which is colorless at room temperature and develops a color by heating or cooling. A suitable temperature indicator satisfying these conditions is a spiropyran compound.

The method for microencapsulation of the temperature indicator may be a conventional one in a conventional microencapsulation method, and is not particularly limited. For example, an interfacial polymerization method, an in-situ method, a coacervation method, an orifice method and the like can be used. A preferred example of microencapsulation is as follows. A warming agent is added to an acidic aqueous solution of a styrene-maleic anhydride copolymer, followed by high-speed stirring to emulsify or disperse. On the other hand, an alkali is added to a mixed solution of formalin and melamine to adjust the pH to 8 to 10, and then heated to about 50 to 100 ° C to prepare an aqueous solution of a melamine-formaldehyde precondensate composed of methylolated melamine. Next, the aqueous solution of the melamine-formaldehyde precondensate is added to an emulsion or dispersion containing the styrene-maleic anhydride copolymer and a temperature indicator, and the mixture is stirred at about 40 to 90 ° C. for 30 minutes to 4 hours while stirring. Then, a wall film made of a melamine resin is formed around the temperature indicator to obtain an aqueous solution of microcapsules containing the temperature indicator.

As a method for removing water from the thus obtained aqueous solution of microcapsules encapsulating a thermosetting agent and incorporating the microcapsules encapsulating a thermostat into hot melt wax and / or a thermoplastic resin, an aqueous solution of microcapsules encapsulating a thermostat is used. The microcapsule powder is dried by a dry spray method, and the obtained microcapsule powder is generally kneaded with a predetermined hot-melt wax or a thermoplastic resin, or a mixture thereof. Add a lower alcohol such as glycols to the oil (add oils such as spindle oil if necessary)
A method in which water is vaporized using a vacuum dehydration method and then mixed with a hot-melt wax or the like is preferable.

According to this method, since the powdering step is not performed, the capsules do not bind to each other to form enlarged particles.
In addition, since the physical properties such as elasticity and strength at the time of capsule formation are not impaired, the heat-sensitive transfer layer can be suitably formed on the substrate surface by a special coating machine or an offset printing machine. The content of the microcapsules containing the thermosetting agent in the heat-sensitive transfer layer depends on the coloring density.
%, Preferably 10 to 60%, more preferably 20 to 60%.
About 50% is good.

This heat-sensitive transfer layer is provided on the substrate surface by a coating machine or a printing machine, and is formed as a heat-sensitive transfer ribbon for a thermal printer. The application amount of the thermal transfer layer is the same as that of the conventional thermal transfer ribbon, and may be 1 to 10 g per square meter of the substrate. The thus-obtained thermal transfer ribbon is usually housed in a cassette like a conventional thermal transfer ribbon, and used for printer printing in the same manner as the conventional one.

When the recipient visualizes confidential information printed on a postcard, greeting card, or the like with the thermal transfer ribbon of the present invention, a temperature change corresponding to the color development / decoloration and discoloration temperature of the temperature indicator is given. Well, for example, put a postcard or greeting card in the refrigerator and cool it, or blow the hot air of the dryer and heat it to make the invisible information develop from colorless to colored, or to change the color and cause the printing part or Information can be visualized by, for example, causing a contrast with a specific color of the base material.

[0021]

According to the heat-sensitive transfer ribbon of the present invention, since the heat-sensitive transfer layer contains microcapsules containing a thermosetting agent, the heat-sensitive transfer layer can be used for a postcard or a greeting card by using a general thermal printer. The secret information that the user does not want to be printed can be printed in an invisible state, and the receiver can visualize the information by simple means.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a basic configuration of a thermal transfer ribbon of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer ribbon 2 Base material 3 Thermal transfer layer

Claims (1)

[Claims] 1. A heat-sensitive transfer ribbon having a heat-sensitive transfer layer provided on a substrate surface, wherein the heat-sensitive transfer layer mainly comprises a hot-melt wax and / or a thermoplastic resin containing microcapsules enclosing a thermostat. A thermal transfer ribbon characterized by the following: