摘要：
A check paper is being described which is protected against falsifications and forgeries. Crushable micro capsules are being embedded in check paper which contain on one hand a leuco ink and on the other hand a color acceptor. The color acceptor can also be stored in the body of the paper without the use of micro capsules. The leuco ink and the color acceptor react together under color development or color changes if the micro capsules burst through imprinting or other local pressure application to the paper surface. Thus, a character written on the paper surface becomes visible within the body of the paper and cannot be forged anymore.
权利要求：
1. A security protected against forgery and falsification equipped with crushable microcapsules containing a leuco dye, and a dye acceptor which reacts with the leuco dye forming or modifying colors, said security containing the microcapsules and the dye acceptor within the paper pulp and the paper exhibiting two layers which are united during production, characterized in that the dye acceptor (2) and the leuco dye (1) are jointly present only in the interface between two layers.
2. A security as in claim 1, characterized in that the microencapsulated leuco dye (1) and the dye acceptor (2) are each present only in certain layers of the paper which are adjacent to one another.
3. A security as in claim 1, characterized in that the dye acceptor (2) or the microencapsulated leuco dye (1) is present in a certain layer, on the one hand, and the other is present on a plane of the paper adjacent to the layer, on the other hand.
4. A security as in any of claims 1 to 3, characterized in that the dye acceptor (2) is also microencapsulated.
5. A security as in any of claims 1 to 4, characterized in that the leuco dye (1) and the dye acceptor (2) are present solely on one and the same inner plane of the paper.
6. A security as in any of the above claims, characterized in that the leuco dye (1) and/or the dye acceptor (2) is/are present only in certain flat parts of the paper.
7. A security as in claim 6, characterized in that the flat areas have the form of geometrical patterns.
8. A method of producing a security as in claim 2 on a twin wire paper machine, characterized in that the microencapsulated leuco dye is added to the pulp of one web and the dye acceptor is added to the pulp of the other web.
9. A method of producing a security as in claim 3 on a twin wire paper machine, characterized in that the microencapsulated leuco dye or the dye acceptor is added to the pulp of one web and the other component is applied between the webs.
10. A method of producing a security as in claim 5 on a twin wire paper machine, characterized in that the leuco dye and the dye acceptor are applied between the two webs before the latter are joined.
11. A method as in claim 9 or 10, characterized in that the leuco dye and/or the dye acceptor is/are sprayed between the webs by means of nozzles.
12. A method as in claim 11, characterized in that the leuco dye and/or the dye acceptor is/are sprayed suspended in a liquid.
13. A method as in any of claims 9 to 12, characterized in that the leuco dye is applied in the form of patterns or series of lines.