Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Patent
1992-05-07
1994-01-04
Buffalow, Edith
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
428325, 428328, 428500, B32B 300
Patent
active
052758702
DESCRIPTION:
BRIEF SUMMARY
The present invention concerns a watermarked, printable plastic support containing security markings which look like watermarks. Hereafter these markings are called pseudo-watermarks.
It is commonplace to watermark paper. Paper watermarking may be carried out in different ways depending on making "genuine" ones or artificial ones called "pseudo watermarkings".
It is known that trust papers and securities comprise watermarks which are made during the manufacture of the sheet of paper by using round forms impressing hollowed or raised means or using watermarking rollers comprising hollowed and/or raised drawings in association with a flat bench (Fourdrinier machine). An image is then obtained which when looked at against the light will appear clear if the watermarking roller comprises a raised design or dark if its design is hollowed. The clear zones arise from the thickness and the fiber density of the sheet being less than in the areas where the watermarking roller did not print. On the other hand, the dark zones arise from more substantial sheet thickness and fiber density.
It is also known to make pseudo watermarks by printing or depositing a composition, which as a rule is fatty, that shall render the sheet of paper permanently transparent. Transparency also may be achieved by means of a hot-melt substance; this substance is a polyethylene in the European patent application 203,499.
A pseudo watermark may also be produced in a sheet of paper by rendering specific zones more opaque with the use of an opaquing agent.
French patent application 2,353,676 describes a method using an opacity-controlling agent, that is one that increases the opacity, or, alternatively, decreases it.
This agent may be an aqueous suspension of a pigment or filler or a solution of a chemical compound, of a dyed compound or of a dye. While the sheet is being manufactured, this agent is applied to the fiber web before it is removed from the wire cloth so that said agent enters the web interstices and, following drying, shall have altered the opacity of the web being treated in the desired zones.
This method entails the drawback of requiring special rolling equipment to apply this agent and the use, preferably, of a suction device to cause the agent to enter the web interstices.
This complex procedure results in non-homogeneous pseudo watermarks because the deposition is uneven.
U.S. Pat. No. 4,520,063 describes a synthetic-resin sheet with security markings similar to watermarks. Two dyes with different rates of migration are applied to the sheet, the migration of the quicker-migrating dye being stopped by crosslinking due to a crosslinking agent contained in the sheet or added to the dye. Under reflected light, a pattern assuming the color of this dye will be observed, whereas observation under transmitted light shows mixed colors.
It is difficult to make a pseudo watermark in this manner in a plastic sheet because it requires a non-obvious selection of dyes with differing rates of migration into a specific material and it requires crosslinking.
It may be advantageous to replace the sheet of paper with a sheet of synthetic material, which consists essentially of cellulose fibers for example, in the manufacture of long lasting documents or documents which must withstand highly adverse handling. Such documents, for instance may be diplomas required to last at least the life of their holders. Other documents may be securities, banknotes, identification cards and passports.
It is important that such documents bear items of authenticity, in particular watermarks, as the paper documents do.
The watermarking techniques described above in relation to paper can be applied only with difficulty to plastic sheets. They are particularly inapplicable to sheets having a thermoplastic-film base.
Accordingly, one object of the invention is to create a plastic sheet which can be imprinted and which comprises authentication or security markings that are hardly visible, or not at all, in reflected light, and which are perfectly visible in transmitted
REFERENCES:
patent: 2331575 (1943-10-01), Simons
patent: 4520083 (1985-05-01), Simon et al.
patent: 5085936 (1992-02-01), Herdman
Barthez Alain
Halope Christophe
Menez Jean-Paul
Arjo Wiggins S.A.
Buffalow Edith
LandOfFree
Watermarked plastic support does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Watermarked plastic support, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Watermarked plastic support will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-305793