Patent Application
20220072840
None.
N/A
Intrusion resistant thermal laminating films for forming ID cards and secure documents to prevent or deter counterfeiting and forgery of written material within the film.
Intrusion resistant films are required to prepare secure documents and ID cards, for example, that cannot be altered by counterfeiters and forgers. At the core of secure documents and ID cards is a polymeric layer bearing printed information. An optically clear external layer covering the printed layer allows for viewing of the printed material. If a film is not intrusion resistant, a counterfeiter can peel the external layer from printed layer and alter the printed material. Those intent on altering the printed information can resort to techniques, typically using a digitally controlled hot plate to delaminate the film to expose the printed material to allow for alteration. Once altered, the external layers are reapplied to the printed sheet to appear original. U.S. Pat. No. 9,222,004 discloses an intrusion resistant film having a substrate of polycyclohexylenedimethylene terephthalate coated with a thermal adhesive of a blend of one or more alkyl acrylate or alky acrylic acid copolymers and low-density polyethylene. Suitable alkyl acrylic acid copolymers include ethylene acrylic acid, ethylene methacrylic acid, and combinations thereof. The '222 patent discloses that most thermal laminating films will easily delaminate because the substrate is an oriented polyester terephthalate with a high crystallinity.
Disclosed herein is an intrusion resistant thermal laminating film having a first multilayer structure of a polyester polymer layer and an ethylene methyl acrylate copolymer (EMA) layer adhered thereto. The multilayer structure having been exposed to UV radiation for an effective period to ensure the layers to not delaminate. A first adhesive layer is on the first multilayer structure. The first adhesive layer is an ethylene vinyl acetate copolymer (EVA) or an ethylene ethyl acrylate copolymer (EEA). A printed layer of a polyolefin or a polyvinyl chloride is attached to the first adhesive layer. The film has high optical clarity and the EMA layer cannot be separated from the polyester layer without destroying the film. The film exhibits no signs of orange peel and is free of a primer.
Also disclosed herein is a method of forming an intrusion resistant thermal laminating film. The method includes: (1) providing a first web of a polyester sheet material; (2) applying an ethylene methyl acrylate copolymer or an ethylene ethyl acrylate copolymer (EEA) to the polyester sheet to form a first multilayer structure; (3) exposing the first multilayer structure to UV light for an effective period; (4) applying a first adhesive to the EMA layer or EAA layer by extrusion coating, the first adhesive is an ethylene vinyl acetate copolymer (EVA) or an ethylene ethyl acrylate copolymer (EEA); (5) providing a printed sheet of a polymeric material; and, (6) attaching the printed sheet to the first adhesive.
Other features and advantages of the invention will be apparent from the following specification taken in conjunction with the following Figures.
To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings and attachments in which:
While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.
No photoinitiators are required in the process. Also, no primers were used which resulted in a film that shows no signs of orange peel. Orange peel is a bumpy texture that resembles the skin of an orange and is undesirable in laminating films.
The three-layer polymeric structure 28 is contacted with a second chill roll 23 and is wound up on the storage roll 20 for storage or shipment. It is also contemplated the take up roll can be replaced by additional extrusion stations or laminating stations to add additional layers to the three-layered polymeric structure.
A four-layer film was constructed as described above having the following layer structure PET/EMA/EVA/polyolefin based synthetic paper (TESLIN®). The film was cut into four 10 mm wide test sections and subjected to peel strength testing. An INSTRON® tester was connected to the polyolefin layer and the PET/EMA/EVA layer and one layer was pulled at a rate of 254 mm/min at a 90° angle. The film could not be delaminated without destroying the film. Samples of the film were also subjected to a Polaroid Environment Test. Samples of the film were placed in a pressure cooker above, and not immersed, in 225 ml of water. The pressure cooker was placed in an oven at 71° C. for five days. Next the samples were placed in a gallon paint can along with 20 grams of ASTM C778 sand and 30 ml of distilled water. The gallon can was shook for three hours using a commercial paint shaker. The samples were removed, washed, and dried and visually examined. The samples showed some signs of rounded, worn or abraded corners, but no samples showed any signs of delamination. The film had a smooth surface and showed no signs of orange peel. The film is free of a primer which can cause clouding of the film.
Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood within the scope of the appended claims the invention may be protected otherwise than as specifically described.
