Card, formed by laminating a plurality of plastic films, carrying a print within the laminate, and method for forming said card

Description

[0001] The invention relates to a card-formed as a laminate of at least three plastic films and carrying an image in a printing technique being distributed over two film faces within the laminate.

[0002] Furthermore the invention relates to a method for laminating plastic films into a card while enclosing an image printed with ink in the laminate.

[0003] A similar card and a similar method for laminating a card are known from British patent specification No. 2 076 337. The image being enclosed among the films forming the laminate is inaccessible for falsifiers of said print other than by taking the laminate apart. Provided that the adherence between the films is good, separation of the laminate will cause serious and unrepairable damage of the films and of the printed image in particular. Repair of the card after separating the laminate without any visible damage is virtually impossible. Thus the card is protected against falsification in the above sense. Good adherence of the films as required having this object in mind is prejudiced by the printed image that locally bars direct contact between the films.

[0004] According to the invention the above disadvantage is avoided in that the plastic material of the films forming the card is a copolymer or homopolymer polyvinylchloride and in that printing of the image is carried out with a thermosetting vinyl ink, a so-called HSV-ink.

[0005] The method for laminating a card according to the invention is characterized by stacking the films to be laminated while enclosing the image and compressing same by application of pressure onto their full surface areas, subsequently heating the films while maintaining said pressure, and finally cooling the films while maintaining said pressure, the transparent plastic films consisting of copolymer or homopolymer polyvinylchloride and the printing ink being a thermosetting vinyl ink, a so-called HSV-ink.

[0006] A special measure contributing to the good adherence includes that the printed image is substantially a line pattern as usual for securities, the ratio of printed to unprinted surface area amounting to at most 50% in an interface between two films, the image being printed "bled-off".

[0007] To illustrate the invention the following description of an embodiment is given.

Example

[0008] A card was manufactured by laminating four polyvinylchloride films with a format of 350 x 480 mm as follows.

[0009] Two of the films with a thickness of 0.2 mm were unilaterally offset printed image-wise with an HSV-ink.

[0010] As cover films a transparent film having a thickness of 0.1 mm and a transparent film having a thickness of 0.3 mm were used. The films were compiled to form a package and four of such packages were placed between two chromium nickel polishing plates in a laminating press and heated therein up to 150^oC, while applying a force of 10 kN. During cooling the force was raised to 0.6 MN. After heating the process took less than 9 minutes.

Claims

1. A card formed as a laminate of at least three plastic films and carrying an image in a printing technique and being distributed over two film faces within the laminate, characterized in that the plastic material of the films is a copolymer or homopolymer polyvinylchleride, and in that the image is printed with a thermosetting vinyl ink, a so-called HSV ink.

2. A card according to claim 1, characterized in that the printed image is substantially a line pattern as usual for securities, the ratio of printed to unprinted surface area amounting to at most 50% in an interface between two films, the image being printed "bled-off".

3. A method for laminating a card of plastic films while enclosing an ink-printed image within the laminate, characterized by stacking the films to be laminated while enclosing the image and compressing same by application of pressure onto their full surface areas, subsequently heating the films while maintaining said pressure and finally cooling the films while maintaining said pressure, the transparent plastic films consisting of copolymer or homopolymer polyvinylchloride, and the printing ink being a thermosetting vinyl ink, a so-called HSV-ink.