GB1593574A

GB1593574A - Electrosensitive recording material

Info

Publication number: GB1593574A
Application number: GB16289/78A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-10-22
Filing date: 1978-04-25
Publication date: 1981-07-22
Also published as: IT7823068V0; AU4063778A; FR2406525A1; NL7810542A; FR2406525B1; SE7810908L; DE2747485A1; JPS5467637U

Description

(54) ELECTROSENSITIVE RECORDING MATERIAL (71) We, ROBERT BOSCH GmbH, a German company of 50, Postfach, Stuttgart, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: The present invention is concerned with electrosensitive recording.

Electrosensitive recording materials are known which comprise a substrate having thereon at least one intermediate layer and a vapour-deposited metallic layer, such materials being used in a recording method in which electrical energy is supplied from recording electrodes to selected locations of the recording material so as to cause the metallic layer to be burn out at such selected locations.

Various types of intermediate layer have been proposed for such recording materials.

For example, German Auslegeschrift 2344654 discloses an intermediate layer, which acts as a contrast layer on burning out of the metallic layer, and which comprises a dried printing ink. Recording materials of the type disclosed in the above-mentioned German Auslegeschrift produce legible recorded traces; however the intermediate layer is not impervious to gases, so that the resistance to corrosion of the metallic layer is not entirely satisfactory unless a relatively thick intermediate layer is applied.

German Offenlegungsschrift 2204509 describes an electrosensitive recording material comprising a substrate having thereon an intermediate layer comprising a laquer and a vapour-deposited aluminium or aluminium alloy layer. Although such an intermediate layer can provide satisfactory vapour-barrier properties, it is difficult to ensure sufficient contrast between the burnt-out locations and the remainder of the vapour-deposited layer.

We have now devised an improved electrosensitive recording material, which comprises a substrate having thereon, in the order specified, a continuous vapour-barrier coating layer of dried lacquer, a matt layer of dried printing ink, and a continuous vapour-deposited metallic outer layer in contact with the surface of the layer of printing ink, the metallic layer being capable of being selectively burnt out on application of one or more recording electrodes to selected locations thereof.

The present invention extends to a combination of a recording material according to the invention and one or more recording electrodes; and to a recording method which comprises supplying electrical energy from one or more recording electrodes to selected locations of a recording material according to the invention so as to cause the metallic layer to be selectively burnt out at the selected locations.

The arrangement of layers in the recording material according to the invention enables the advantageous features of both a lacquer layer and a printing ink layer to be employed, the resulting material having good readability and resistance to corrosion. Thus, the lie- quer layer has good vapour-barrier properties, while the ink layer can be highly coloured (containing, for example a high concentration, such as at least 15% by weight, of a pigment, such as carbon black) and has a matt surface, which ensures that recorded characters obtained in the recording method accord in to the invention have good legibility. The lacquer layer minimises any problems caused by roughness and absorbency of a paper substrate.

The lacquer layer and the printing ink layer may each consist of one or more sublayers, which may be the same or different.

Different sub-layers of lacquer may be pigmented or pigment-free.

The recording material according to the invention may be produced economically, the lacquer layer being preferably applied by roller coating and the printing ink layer being applied by gravure printing. In this case, the lacquer layer and the printing ink layer are preferably applied in successive operations in a combined roller-coating and gravure printing apparatus.

The substrate in the recording material according to the invention may be of plastics foil, but it is-preferably of paper in view of the cheapness thereof and the ease of application of coating layers thereto.

The metallic layer is preferably of aluminium; recording materials according to the invention with such an aluminium layer can be used in place of conventional zinccadmium recording papers.

A particular embodiment of the invention will now be described with reference to the accompanying drawing, which is a diagrammatic cross-section ot a recording material according to the invention, on a greatly enlarged scale.

In the drawing, there is shown a paper substrate 10 having thereon a continuous vapour-barrier coating layer 11 of dried lacquer, a layer 12 of dried printing ink and a vapour-deposited aluminium layer 13.

Layer 11 may be formed from a lacquer such as a nitrocellulose lacquer (e.g. Nitrolack); the lacquer is preferably pigmentfree but coloured with a soluble colouring agent and applied to the paper substrate 10 by means of a roller-applicator.

Layer 12 (which forms a contrast layer in use of the recording material) is preferably formed from a black pigmented nitrocellulose-based printing ink, and is applied by gravure printing.

Layers 11 and 12 are advantageously applied, in a manner known per se, in successive operations in a combined roller-coating and gravure printing aparatus.

As can be seen from the Figure, layer 12 need not be continuous; discontinuities (as represented by 14 in the Figure) may be formed during application of the layer 12.

These discontinuities, which may be a printed pattern in the form of coordinates, numerals or writing, may be formed by means of corresponding formations on the gravure printing plate used. These discontinuities are visible because of the contrast of the printing ink layer 12 in the coated areas and the underlying lacquer layer 11.

Layer 11 may be of a different colour to layer 12, whereby on burning out of the overlying aluminium layer 13 in use, the colour of layer 11 becomes visible in the region of such discontinuities.

If desired, the printing ink layer 12 may be applied to the lacquer layer 11 by a multicolour printing technique.

The recording material illustrated can be used in the usual way by generating an arc at selected locations on the aluminium layer 13, using one or more electrodes (not shown), whereby the aluminium layer 13 is burnt out at such locations.

WHAT WE CLAIM IS: 1. An electrosensitive recording material which comprises a substrate having thereon, in the order specified, a continuous vapour-barrier coating layer of dried lacquer, a matt layer of dried printing ink, and a continuous vapour-deposited metallic outer layer in contact with the surlace ot the layer of printing ink, the metallic layer being capable of being selectively burnt out on application of one or more recording electrodes to selected locations thereof.

2. A recording material according to claim 1, in which the metallic layer is of aluminium.

3. A recording material according to claim 1 or 2, in which the substrate is of paper.

4. A recording material according to any of claims 1 to 3, in which the vapour-barrier layer is pigment-free.

5. A recording material according to any of claims 1 to 4, in which the vapour-barrier layer has a colour contrasting with that of the layer of printing ink.

6. A recording element according to any of claims 1 to 5, in which the printing ink contained at least 15% by weight of pigment.

7. A recording material according to claim 6, in which the pigment is carbon black.

8. A recording material according to any of claims 1 to 7, in which the layer of printing ink has discontinuities which constitute a printed pattern.

9. A recording material according to any of claims 1 to 5, in which the layer of printing ink has been applied by a multicolour printing technique.

10. A recording material according to any of claims 1 to 9, in which the layer of printing ink has been applied by a gravure printing process.

11. A recording material according to any of claims 1 to 10, in which the vapourbarrier layer has been applied by means of a roller applicator.

12. A recording material according to claim 11 as appendant to claim 10, in which the vapour-barrier layer and the layer of printing ink have been applied in successive operations in a combined roller-coating and gravure printing apparatus.

13. In combination, a recording material according to any of claims 1 to 12 and one or more recording electrodes.

14. A recording method which comprises supplying electrical energy from one or more recording electrodes to selected locations of a recording material according to any of claims 1 to 13 so as to cause said metallic layer to be selectively burnt out at said selected locations.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. cheapness thereof and the ease of application of coating layers thereto. The metallic layer is preferably of aluminium; recording materials according to the invention with such an aluminium layer can be used in place of conventional zinccadmium recording papers. A particular embodiment of the invention will now be described with reference to the accompanying drawing, which is a diagrammatic cross-section ot a recording material according to the invention, on a greatly enlarged scale. In the drawing, there is shown a paper substrate 10 having thereon a continuous vapour-barrier coating layer 11 of dried lacquer, a layer 12 of dried printing ink and a vapour-deposited aluminium layer 13. Layer 11 may be formed from a lacquer such as a nitrocellulose lacquer (e.g. Nitrolack); the lacquer is preferably pigmentfree but coloured with a soluble colouring agent and applied to the paper substrate 10 by means of a roller-applicator. Layer 12 (which forms a contrast layer in use of the recording material) is preferably formed from a black pigmented nitrocellulose-based printing ink, and is applied by gravure printing. Layers 11 and 12 are advantageously applied, in a manner known per se, in successive operations in a combined roller-coating and gravure printing aparatus. As can be seen from the Figure, layer 12 need not be continuous; discontinuities (as represented by 14 in the Figure) may be formed during application of the layer 12. These discontinuities, which may be a printed pattern in the form of coordinates, numerals or writing, may be formed by means of corresponding formations on the gravure printing plate used. These discontinuities are visible because of the contrast of the printing ink layer 12 in the coated areas and the underlying lacquer layer 11. Layer 11 may be of a different colour to layer 12, whereby on burning out of the overlying aluminium layer 13 in use, the colour of layer 11 becomes visible in the region of such discontinuities. If desired, the printing ink layer 12 may be applied to the lacquer layer 11 by a multicolour printing technique. The recording material illustrated can be used in the usual way by generating an arc at selected locations on the aluminium layer 13, using one or more electrodes (not shown), whereby the aluminium layer 13 is burnt out at such locations. WHAT WE CLAIM IS:

1. An electrosensitive recording material which comprises a substrate having thereon, in the order specified, a continuous vapour-barrier coating layer of dried lacquer, a matt layer of dried printing ink, and a continuous vapour-deposited metallic outer layer in contact with the surlace ot the layer of printing ink, the metallic layer being capable of being selectively burnt out on application of one or more recording electrodes to selected locations thereof.