WO2009063058A1

WO2009063058A1 - Biaxially oriented polyester lamella for security laminates

Info

Publication number: WO2009063058A1
Application number: PCT/EP2008/065567
Authority: WO
Inventors: Ingrid Geuens
Original assignee: Agfa-Gevaert Nv
Priority date: 2007-11-15
Filing date: 2008-11-14
Publication date: 2009-05-22

Abstract

A security laminate comprising at least one biaxially oriented polyester lamella and an adhesion system associated therewith and on at least one side thereof, said adhesion system comprising a layer system comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene, said layer system being contiguous with said at least one biaxially oriented polyester lamella, wherein at least that part of said layer system contiguous with said polyester lamella was contiguous with said polyester lamella during at least part of the biaxial orientation of said at least one polyester lamella and wherein said layer system has a thickness of at least 1.0 μm; an adhesion system contiguous with a biaxially oriented polyester sheet, said adhesion system comprising a layer system comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene, said layer system being contiguous with said biaxially oriented polyester sheet, wherein at least that part of said layer system contiguous with said polyester lamella has been stretched during at least part of the biaxial orientation of said polyester sheet and wherein said layer system has a thickness of at least 1.0 μm; and a process for providing an adhesion system on at least one side of a biaxially oriented polyester sheet, said adhesion system comprising a layer system having a thickness of at least 1.0 μm contiguous therewith, said process comprising the steps of : biaxially stretching a polyester sheet with at least that part of said adhesion system contiguous with said polyester sheet being contiguous therewith during at least part of the biaxial stretching process, said part of said adhesion system contiguous with said polyester sheet being a layer having a composition comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene; and optionally applying a coating to said layer using conventional coating techniques, said layer and said optional coating being comprised in said layer system.

Description

BIAXIALLY ORIENTED POLYESTER LAMELLA FOR SECURITY LAMINATES

FIELD OF INVENTION

This invention relates to security laminates comprising at least one biaxially oriented polyester lamella and an adhesion system associated therewith.

BACKGROUND OF THE INVENTION

Security laminates are traditionally used to protect documents or packages to ensure that the underlying items are not altered by containing an authentif ication feature making them difficult to counterfeit. Security laminates are particularly useful on identification cards such as driver's licenses, ID-cards and passports, and on other important documents such as certificates of title. Security laminates are also useful as tamper proof seals on medications, video cassettes, and compact discs. Five features are particularly important when producing and using security laminates. First, once applied to an article it is important that the laminate is difficult to remove to ensure that the underlying item is not altered or subjected to tampering. Second, a desirable laminate is difficult if not impossible to duplicate by counterfeiters. Third, if tampering occurs it is important to quickly and accurately recognize an altered or counterfeit laminate. Fourth, it is important that manufacturing costs of the laminates are not prohibitively expensive. Fifth, when used on articles such as identification cards, it is important that the laminate has sufficient durability to withstand harsh treatment. The use of ID cards has become widespread, especially for driver's licenses, national ID cards, bank and other authority cards, for example. Security is important for such cards, and an important security feature of such cards is the use of a continuous tone color photograph printed in the same layer along with other personal, variable data. This type of information can be rapidly and conveniently placed onto an ID card by use of an electronic camera, a computer, and a computer-controlled digital printer. For example, a video camera or a digital still camera can be used to capture a person's image and a computer can record the corresponding personal, variable data.

The convenience and rapid access of electronically-generated ID cards makes desirable an ID card stock pre-cut to the proper size, readily transportable through a printer, and capable of exiting the printing hardware in the form of a finished card. Off-line lamination after printing and die cutting to size after lamination are undesirable because of the manual labour and time required. Poly(vinyl chloride) (PVC) and/or poly(vinyl chloride/acetate) , polyesters, polyethylenes and polycarbonates are known for use as ID card materials. PVC-based cards have been the most widely used, but such cards have a short lifetime of only one to two years due to the marginal physical properties of PVC. PVC is also known to readily absorb plasticizers from other objects thereby further degrading its physical properties.

US 3,374,197 discloses a coalescible aqueous coating composition of a blend of vinylidene dispersions which comprises (1) between 50% and about 75% by weight of the total solids in said blend of a first aqueous vinylidene chloride copolymer dispersion containing between about 92 and about 96 parts by weight of vinylidene chloride between about 8 and about 4 parts by weight of an alkyl acrylate wherein the alkyl group contains from one to three carbon atoms and between about 0.5 and about 5 parts by weight of itaconic acid, wherein a coalesced film of said first aqueous dispersion is characterized by an infrared reflectance ratio between about 1.25 and about 1.55 and ((2) between about 50% and about 25% by weight based upon the total solids content of said blend of a second aqueous vinylidene chloride dispersion which contains between about 80 and 91.5 parts by weight of vinylidene chloride, between 20 and 8.5 parts by weight of acrylonitrile and between about 0.5 and about 5 parts by weight of itaconic acid, wherein a coalesced film of said second dispersion is characterized by an infrared reflectance ratio no greater than 1.15, and further wherein a coalesced film of said blend of dispersions is characterized by an infrared relectance ratio between about 1.35 and about 1.50.

US 3,988,157 discloses a process for adhering hydrophilic layers to dimensionally stable polyester film supports, which comprises applying to polyester film unstretched in at least its transverse direction an adhesive layer from an aqueous coating dispersion comprising as the dispersal phase a chlorine-containing copolymer formed of 45 to 99.5% by weight of at least one of the monomers vinylidene chloride and vinyl chloride, 0.5 to 10% by weight of an ethylenically unsaturated mono- or dicarboxylic acid or of N-vinylpyrrolidone, and 0 to 54.5% by weight of at least one copolymerizable monomer taken from acrylamides, methacrylamides , esters of acrylic acid, methacrylic acid and maleic acid, and N- alkyl maleimides; immediately applying thereto, without drying of said adhesive layer, a subbing layer from an aqueous gelatin solution containing a plasticizer for the gelatin, drying the two layers, stretching the thus-coated polyester film support to biaxially orient the same at a temperature up to about 90⁰C, heat- setting the stretched coated support, and applying to the subbing layer a hydrophilic layer.

US 5,610,001 discloses a a web or sheet material is provided which comprises a hydrophobic resin support having coated directly thereon a primer layer essentially consisting of a mixture of ingredients (A) , (B) and (C) applied as a dispersion from aqueous medium, wherein: (A) is a copolyester containing recurring ester groups derived from ethylene glycol and an acid mixture containing terephthalic acid, isophthalic acid and 5-sulphoisophthalic acid whose sulpho group is in salt form, said acid mixture consisting essentially of from 20 to 60 mole % of isophthalic acid, 6 to 10 mole % of said sulphoisophthalic acid, 0.05 to 1 mole % of cross- linking agent being an aromatic polycarboxylic acid compound having at least three carboxylic acid groups or corresponding acid generating anhydride or ester groups, the remainder in said acid mixture being terephthalic acid; (B) is a copolymer formed from 45 to 70% by weight of a lower (C1-C4) alkyl methacrylate, 25 to 50% by weight of butadiene and from 2 to 5% by weight of an ethylenically unsaturated carboxylic acid, and (C) is colloidal silica. US 6,644,552 discloses a multilayered card comprising: a first core layer made of one of the following materials polyvinyl chloride (PVC) , amorphous polyester terephthalate (APET) , PETG, compounds of PVC, and polyvinyl chloride acetate (PVCA) ; a first buffer layer attached to the top surface of the first core layer; a second buffer layer attached to the bottom surface of the first core layer; wherein the buffer layers are made of one of the following materials a copolymer of PVC and polyethylene (PE) , a copolymer of PVC and polyvinyl acetate, polyolefins, ethylene, vinyl acetate, amorphous polyesters and acrylics; and a first strengthening layer attached to the top surface of the first buffer layer and a second strengthening layer attached to the bottom surface of the second buffer layer; wherein the strengthening layers are formed of one of oriented PET and polycarbonate . \

US 4,450,024 discloses an identification card equipped with an integrated circuit, in which the circuit along with its connection leads is arranged on a carrier element which is embeddedly enclosed by the card on all sides by use of the hot lamination technique. US 4,450,024 further discloses that in order to protect the sensitive arrangement, the carrier element is subjected to the full laminating pressure only when one or more layers in the card construction have softened, which is achieved, for example, by providing buffer zones 5 in the card laminate at least in the area of the arrangement in the form of cavities or layers that are easy to deform elastically. The buffer zones protect the arrangement from local pressure peaks in the initial phase of the laminating process. US 4,450,024 also discloses that it is possible to control the laminating pressure aso a function of the temperature or the degree of softening of the card layers. US 4,450,024 also discloses the use of polyester films coated with polyethylene as cover layers for the identification cards disclosed using the polyethylene as an adhesive layer. US 5,171,625 discloses an all polyester composite film s structure having: (a) an opaque, biaxially oriented polyester support core film, (b) a clear, biaxially oriented polyester top film, and (c) a first pair of dye receptive or printable receiver films that can be heat sealed together and sandwiched between the top surface of the core film and one surface of the top film whereino at least one surface of a receiver film of the first pair of receiver films is printed with a dye to form printed matter.

US 5,407,893 discloses an ID card material comprising a thermal transfer image-receiving layer, and provided thereon, a substrate layer and a writing layer in this order, wherein the substrate layer5 consists of a biaxially oriented polyester film layer having a thickness of 300 to 500 μm.

US 5,733,845 discloses an identification card stock comprising a polymeric core substrate having on at least one side thereof the following layers in order: a hydrophobic antistatic layer, an 0 oriented polymeric film, e.g. biaxially oriented polyester, and an image-receiving layer; and process of using same. US 5,733,845 further discloses that the composite ID card stock of the invention can also be readily milled for placement of a memory chip and alternatively that the polymeric core substrate and an oriented5 polymeric film can be pre-punched before attaching to provide a suitable site for a memory chip.

US 5,746,864 discloses a process of providing a smooth surface to an image-receiving laminate in an identification card stock, the laminate comprising an oriented polymeric film support, e.g. 0 biaxially oriented polyester, having an image -receiving layer located on a first outermost surface thereof, and the second outermost surface of the oriented polymeric film support having a heat- or chemically-activated adhesive thereon, the process comprising applying an embossed surface to the image-receiving layer using a textured plate employed m a laminating process, and then applying a smooth surface to the image -receiving layer using a 5 smooth plate employed in a laminating process US 5,746,864 further discloses that the composite ID card stock made with the invention can also be readily milled for placement of a memory chip and alternatively that the polymeric core and image-receiving laminate can be pre-punched before laminating for insertion of a memory chipo US 5,756,188 discloses an image-receiving laminate for an identification card stock, the laminate comprising an oriented polymeric film support having an image-receiving layer located on a first outermost surface thereof, the image-receiving layer having an embossed surface, and the second outermost surface of the orienteds polymeric film support having a heat- or chemically-activated adhesive thereon, with the oriented polymeric film being preferably biaxially oriented poly (ethylene terephthalate) . US 5,756,188 further discloses that the composite ID card stock made with the invention can also be readily milled for placement of a memory chip0 and alternatively that the polymeric core and image-receiving laminate can be pre-punched before laminating for insertion of a memory chip .

US 5,789,340 discloses an identification card stock comprising a polymeric core substrate having on at least one side thereof the5 following layers m order: an oriented polymeric film, a cushion layer of an acrylic polymer, a subbing layer and an image-receiving layer; wherein the subbing layer comprises from about 5 to about 35% by weight of acrylonitπle, from about 2 to about 10% by weight of acrylic acid, and from about 55 to about 85% by weight of recurringo units of vinyl idene chloride; and process of using same US

5,789,340 further discloses that the composite ID card stock of the invention can also be readily milled for placement of a memory chip and alternatively that the polymeric core substrate and an oriented polymeric film can be pre-punched before attaching to provide a5 suitable site for a memory chip

US 5,846,900 discloses an identification card stock comprising a polymeric core substrate having an oriented poly (ethylene terephthalate) film laminated on at least one side thereof, said card stock also having an image-receiving layer located on the0 outermost surface of at least one side of said card stock US

5,846,900 further discloses that the composite ID card stock of the invention can also be readily milled for placement of a memory chip and alternatively that the polymeric core substrate and an oriented polymeric film can be pre-punched before attaching to provide a suitable site for a memory chip.

US 6,066,594 discloses an identification document comprising: a core layer bearing at least one indicium thereon; two layers of a substantially transparent polymer fixed to the core layer on opposed sides thereof; and at least one image-receiving layer capable of being imaged by dye diffusion thermal transfer, the image -receiving layer being fixed to one of the layers of substantially transparent polymer on the side thereof remote from the core layer. US 6,066,594 further discloses that the protective layer will typically be a biaxially oriented polyester or other clear durable plastic film.

US 6,923,378 discloses an identification document comprising: a core layer comprising a substantially non-rigid material, the core layer having a first side and a second side; at least one antenna affixed to the first side of the core layer; an anti-binding agent printed on the first side of said core layer and positioned between the antenna and the first side of the core layer; at least one integrated circuit chip electronically connected to the antenna; and a bottom sheet comprising a substantially non-rigid material, the bottom sheet being attached to the first side of the core layer such that the antenna mid the chip are encased between the core layer and the bottom sheet. In Figure 1 of US 6,923,378 the core layer 12 and bottom layer 14 are sandwiched between two polymer layers 30 formed from an amorphous or biaxially oriented polyester or other optically clear plastic such as polycarbonate.

US 7,278,580 discloses an identification document comprising: a core layer, the core layer having a first side and a second side; at least one antenna affixed to the first side of the core layer; an anti -binding agent printed on the first side of said core layer and positioned between the antenna and the first side of the core layer; at least one integrated circuit chip electronically connected to the antenna; and a bottom sheet attached to the first side of the core layer such that the antenna and the chip are encased between the core layer and the bottom sheet. US 7,278,580 further discloses that two layers of substantially transparent polymer are affixed to the bonded core layer/bottom layer structure. The polymer layers themselves may be formed from any polymer having sufficient transparency, for example polyester, polycarbonate; polystyrene, cellulose ester, polyolefin, polysulfone, or polyimide . Either an amorphous or biaxially oriented polymer may be used. Despite the extensive patent literature in respect of the use of biaxially oriented polyester laminates in identification cards and the undoubted advantages of biaxially oriented polyester-based identification cards over polycarbonate -based identification cards, 5 biaxially oriented polyester-based identification cards have not achieved a substantial market penetration. The principal reason for this lack of market penetration is the absence of a reliable adhesive system for use with biaxially oriented polyester lamellae. o ASPECTS OF THE INVENTION

It is therefore an aspect of the present invention to provide a security laminate comprising at least one biaxially oriented polyester lamella and an adhesion system associated therewiths suitable for use with a wide range of polymeric lamellae.

It is therefore a further aspect of the present invention to provide an adhesion system contiguous with a biaxially oriented polyester sheet suitable for use with a wide range of polymeric lamellae . 0 Further aspects of the present invention will become apparent from the description hereinafter.

SUMMARY OF THE INVENTION 5 An effective adhesive is one which produces a bond of sufficient strength so that cohesive failure occurs within the biaxially oriented polyester rather than at the interface between the biaxially oriented polyester and the layer system contiguous therewith or in the adhesive system itself of which the layer system0 is a part, when an attempt is made to rip apart the multiply identification card. Surprisingly it has been found that excellent adhesion to biaxially oriented polyester can be realized by that part of the layer system contiguous with the polyester lamella being contiguous with the polyester lamella during at least part of the5 biaxial orientation process of the polyester lamella with the additional provision that the layer system have a thickness of at least 1.0 μm. Such layer thicknesses can be either achieved during the biaxial orientation process or part during the biaxial orientation and part by subsequent overcoating with a coating haveo substantially similar ingredients.

Aspects of the present invention have been realized by a security laminate comprising at least one biaxially oriented polyester lamella and an adhesion system associated therewith and on at least one side thereof, said adhesion system comprising a layer system comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene, said layer system being contiguous with said at least one biaxially oriented polyester lamella, wherein at least that part of said layer system contiguous with said polyester lamella was contiguous with said polyester lamella during at least part of the biaxial orientation of said at least one polyester lamella and wherein said layer system has a thickness of at least 1.0 μm .

Aspects of the present invention have also been realized by an adhesion system contiguous with a biaxially oriented polyester sheet, said adhesion system comprising a layer system comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene, said layer system being contiguous with said biaxially oriented polyester sheet, wherein at least that part of said layer system contiguous with said polyester lamella has been stretched during at least part of the biaxial orientation of said polyester sheet and wherein said layer system has a thickness of at least 1.0 μm.

Aspects of the present invention have also been realized by a process for providing an adhesion system on at least one side of a biaxially oriented polyester sheet, said adhesion system comprising a layer system having a thickness of at least 1.0 μm contiguous therewith, said process comprising the steps of: biaxially stretching a polyester sheet with at least that part of said adhesion system contiguous with said polyester sheet being contiguous therewith during at least part of the biaxial stretching process, said part of said adhesion system contiguous with said polyester sheet being a layer having a composition comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene; and optionally applying a coating to said layer using conventional coating techniques, said layer and said optional coating being comprised in said layer system.

Preferred embodiments are disclosed in the dependent claims.

Detailed description of the invention

Definitions The term film, as used in disclosing the present invention, means a self-supporting polymer-based sheet, which may vary in thickness from several microns thick, e.g. the foils used in thermal sublimation printing (TSP) and in the production of multiplex identification documents, to several mm thick.

The term lamella in the terms polymeric lamellae and polyester lamella, as used in disclosing the present invention, means a thin polymeric sheet optionally provided with an adhesive system used in producing laminates using pressure optionally together with heat. The term adhesion system, as used in disclosing the present invention, means one or more layers providing an adhesive entity.

The term layer system, as used in disclosing the present invention, means one or more layers contiguous with one another.

The term chlorinated ethylene, as used in disclosing the present invention, means ethylene substituted with at least one chlorine atom e.g. vinyl chloride, vinylidene chloride, 1,2- dichloro-ethylene , trichloroethylene and tetrachloroethylene . 1,2- dichloro-ethylene, trichloroethylene and tetrachloroethylene Trichloroethylene and tetrachloroethylene are all much more difficult to polymerize than vinyl chloride or vinylidene chloride.

Security laminates

Aspects of the present invention have been realized by a security laminate comprising at least one biaxially oriented polyester lamella and an adhesion system associated therewith and on at least one side thereof, said adhesion system comprising a layer system comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene, said layer system being contiguous with said at least one biaxially oriented polyester lamella, wherein at least that part of said layer system contiguous with said polyester lamella was contiguous with said polyester lamella during at least part of the biaxial orientation of said at least one polyester lamella and wherein said layer system has a thickness of at least 1.0 μm, with a thickness of at least 2.5 μm being preferred, a thickness of at least 5 μm being particularly preferred and a thickness of 7 μm being especially preferred.

According to a first embodiment of the security laminate, according to the present invention, said security laminate comprises a security laminate precursor provided by lamination of the side of said polyester lamella with said adhesion system with a polymeric lamella, said polymeric lamella being preferably selected from the group consisting of an amorphous polyester lamella, a crystalline polyester lamella, a polycarbonate lamella, a polyolefin lamella, a polyvinyl chloride lamella, a polyimide lamella and a polysulphone lamella. According to a second embodiment of the security laminate, according to the present invention, said security laminate comprises a security laminate precursor provided by lamination of said adhesion system with a polymeric lamella, the wet peel strength of said security laminate precursor being at least 6 N/cm² as measured according to ISO Norm 10373-1-1978.

According to a third embodiment of the security laminate, according to the present invention, the adhesion system further comprises a coating contiguous to said part of said adhesion system contiguous with said polyester lamella, said coating having a substantially similar composition to the composition of said part of said adhesion system contiguous with said polyester lamella.

According to a fourth embodiment of the security laminate, according to the present invention, the adhesion system further comprises a coating contiguous to said part of said adhesion system contiguous with said polyester lamella, said coating having substantially similar ingredients to the ingredients of said part of said adhesion system contiguous with said polyester lamella.

According to a fifth embodiment of the security laminate, according to the present invention, the adhesion system further comprises a layer comprising a vinyl chloride copolymer e.g. copolymer comprising vinyl chloride and vinyl acetate monomer units.

According to a sixth embodiment of the security laminate, according to the present invention, said composition comprises a vinyidene chloride copolymer and colloidal particles, said colloidal particles preferably being inorganic colloidal particles and particularly preferably being colloidal silica particles. Suitable organic particles include crosslinked polystyrene particles.

According to a seventh embodiment of the security laminate, according to the present invention, said composition further comprises inorganic particles, preferably colloidal inorganic particles, and particularly preferably colloidal silica particles.

According to an eighth embodiment of the security laminate, according to the present invention, the layer system comprises a copolymer of a chlorinated ethylene together with at least 10% by weight of colloidal silica, with at least 15% by weight of colloidal silica being particularly preferred. According to a ninth embodiment of the security laminate, according to the present invention, said composition further comprises a polyolefin latex.

According to a tenth embodiment of the security laminate, according to the present invention, said composition further comprises a melamine- formaldehyde resin.

According to an eleventh embodiment of the security laminate, according to the present invention, said composition further comprises a copolymer latex of an optionally substituted divinyl olefin e.g. butadiene, isoprene or chloroprene . Suitable copolymer latex of an optionally substituted divinyl olefin include: copolymer latexes of vinylidene chloride and isoprene, vinylidene chloride and butadiene, vinylidene chloride, isoprene and acidic monomers without an α-hydrogen atom such as methacrylic acid and itaconic acid, vinylidene chloride, butadiene and acidic monomers without an α- hydrogen atom such as methacrylic acid and itaconic acid.

* PERBUNAN N LATEX 3415N from BAYER

According to a twelfth embodiment of the security laminate, according to the present invention, said composition further comprises an (meth) acrylate copolymer e.g. copolymers of (meth) acrylates with (meth) acrylic acid.

According to a thirteenth embodiment of the security laminate, according to the present invention, said security laminate is an identity (identification) document.

According to a fourteenth embodiment of the security laminate, according to the present invention, said security laminate is an identification (identity) card. The security laminates of the present invention are readily suited to making a direct pre-cut card with improved physical properties. The ID card stock of the invention provides improved flexural durability over an extended period of time vs. PVC, while retaining good stiffness and impact strength.

Pre-cut ID card stock can be easily produced by conventional methods using the above-described composite film structure in the conventional shape, size, e.g., 54.5 mm x 86 mm, and having a thickness of about 0.8 mm. A pre-cut card stock is one which is made to the card size specifications before printing and exits the printer system without any further trimming or cutting required. An overcoat laminate may be applied after printing if desired. The thickness of both the polymeric core substrate and oriented polymeric film is variable, but the overall thickness is usually in the range of 685 to 838 μm. The outer surfaces of the ID card stock can be printed with dye images or text. Optionally, non-varying information, such as lines, line segments, dots, letters, characters, logos, guilloches, etc., can be printed on the polymeric core substrate by non- thermal dye transfer methods such as flexo or offset printing before attaching the polymeric core substrate to the oriented polymeric film or films carrying the external dye-receiving layer or layers. The composite ID card stock of the invention can also be readily milled for placement of a memory chip. Alternatively, the polymeric core substrate and an oriented polymeric film can be prepunched before attaching to provide a suitable site for a memory chip or in the case of contactless applications the chip can be interlaminated.

Adhesion system

Aspects of the present invention have also been realized by an adhesion system contiguous with a biaxially oriented polyester sheet, said adhesion system comprising a layer system comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene, said layer system being contiguous with said biaxially oriented polyester sheet, wherein at least that part of said layer system contiguous with said polyester lamella has been stretched during at least part of the biaxial orientation of said polyester sheet and wherein said layer system has a thickness of at least 1.0 μm, with a thickness of at least 5 μm being preferred and a thickness of at least 7 μm being particularly preferred. According to a first embodiment of the adhesion system, according to the present invention, the layer system contiguous with the polyester sheet is only stretched during transversal stretching of the polyester sheet.

According to a second embodiment of the adhesion system, according to the present invention, the layer system further comprises a layer comprising a vinyl chloride copolymer e.g. copolymer comprising vinyl chloride and vinyl acetate monomer units.

Process for providing a biaxially oriented polyester sheet with an adhesion system

Aspects of the present invention have also been realized by a process for providing an adhesion system on at least one side of a biaxially oriented polyester sheet, said adhesion system comprising a layer system having a thickness of at least 1.0 μm contiguous therewith, said process comprising the steps of: biaxially stretching a polyester sheet with at least that part of said adhesion system contiguous with said polyester sheet being contiguous therewith during at least part of the biaxial stretching process, said part of said adhesion system contiguous with said polyester sheet being a layer having a composition comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene; and optionally applying a coating to said layer using conventional coating techniques, said layer and said optional coating being comprised in said layer system. According to a first embodiment of the process, according to the present invention, said layer having a composition comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene is coextruded with said polyester sheet.

According to a second embodiment of the process, according to the present invention, the step of biaxially stretching a polyester sheet with at least that part of said adhesion system contiguous with said polyester sheet being contiguous therewith during at least part of the biaxial stretching process orientation comprises the steps of: longitudinally stretching a polyester sheet; applying a composition comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene to said longitudinally- streched polyester sheet to provide a layer of said composition contiguous with said longitudinally- streched polyester sheet; and transversally stretching said longitudinally- stretched polyester sheet. According to a third embodiment of the process, according to the present invention, said layer and said coating have substantially similar compositions. According to a fourth embodiment of the process, according to the present invention, said layer and said coating have substantially similar ingredients.

According to a fifth embodiment of the process, according to the present invention, said process further comprises the step of laminating a polymeric lamella to said biaxially oriented polyester laella by means of said adhesion system, said polymeric lamella being preferably selected from the group consisting of an amorphous polyester lamella, a crystalline polyester lamella, a polycarbonate lamella, a polyolefin lamella and a polyvinyl chloride lamella.

According to a sixth embodiment of the process, according to the present invention, the layer system further comprises a layer comprising a vinyl chloride copolymer e.g. copolymer comprising vinyl chloride and vinyl acetate monomer units. The part of said adhesion system contiguous with said polyester lamella can be applied to a polyester lamella prior to or partway through the biaxial stretching of the polyester lamella by coating using convention coating techniques, extrusion, lamination, extrusion lamination or cold roll lamination.

Biaxially oriented polyester lamella

The thickness of the oriented polymeric lamella employed in the present invention can be between 12 μm and 250 μm. Any orientable polyester can be used in the security laminates, adhesion systems and processes, according to the present invention.

In a preferred embodiment of the invention, a synthetic linear polyester is employed. Such a material is well known to those skilled in the art and is obtained by condensing one or more dicarboxylic acids or their lower (up to 6 carbon atoms) diesters, e.g. , terephthalic acid, isophthalic acid, phthalic acid, 2,5-, 2,6- or 2 , 7-naphthalenedicarboxylic acid, succinic acid, sebacic acid, adipic acid, azelaic acid, 4 , 4 ' -diphenyldicarboxylic acid, hexahydroterephthalic acid or 2-bis-p-carboxyphenoxyethane (optionally with a monocarboxylic acid, such as pivalic acid) , the corresponding dicarboxylic acid dialkyl ester or lower alkyl ester with one or more glycols, e.g., ethylene glycol, 1, 3 -propanediol , 1 , 4-butanediol , neopentyl glycol and 1, 4-cyclohexanedimethanol . In a preferred embodiment, the polyester polymer is obtained by condensing terephthalic acid or 2 , 6-naphthalenedicarboxylic acid or their dimethyl esters with ethylene glycol . In another preferred embodiment, the polymer is PET. The PET film prepared from the above-described composition must be oriented. In a preferred embodiment, the PET film is biaxially-oriented. Such a process is described in many patents, such as GB 838,708, the disclosure of which is hereby incorporated by reference. These techniques are well 5 known to those skilled in the art.

According to a fifteenth embodiment of the security laminate, according to the present invention, the polyester is an orientable polyester with polyesters comprising monomer units selected from the group consisting of terephthalate units, isophthalate units, io naphthalate units, ethylene units, neopentylene units, 1,4- cyclohexane dimethylene units and -CH₂CH₂OCH₂CH₂- units being preferred e.g. polyethylene terephthalate (PET) , polyethylene naphthalate (PEN) .

is Layer system comprising a polyester or polyester-urethane

According to a sixteenth embodiment of the security laminate, according to the present invention, the polyester comprised in said layer system is a linear polyester has monomer units selected from

20 the group consisting of terephthalate units, isophthalate units, naphthalate units, 5-sulpho-isophthalate, units derived from polycarboxylic acids with more than two carboxy- groups , ethylene units, neopentylene units, 1 , 4-cyclohexane dimethylene units and - CH₂CH₂OCH₂CH₂- units. Polyesters with 10 mol% 5-sulpho-isophthalate

25 units are self -dispersing in water. At lower concentrations of 5- sulpho- isophthalate units increasing quantities of surfactant are necessary to compensate for the increasingly poor dispersion properties as the concentration of 5-sulpho-isophthalate units is decreased.

30 According to a seventeenth embodiment of the security laminate, according to the present invention, the polyester or polyester- urethane comprised in said layer system has a minimum film-forming temperature less than 5O⁰C, with a film-forming temperature less than 35⁰C being preferred and a film-forming temperature less than

35 25⁰C being particularly preferred.

According to an eighteenth embodiment of the security laminate, according to the present invention, the polyester comprised in said layer system has a glass transition temperature of less than 60°, with a glass transition temperature of less than 40⁰C being

40 preferred and a glass transition temperature of less than 20⁰C being particularly preferred. Polyesters capable upon application as an aqueous dispersion to a polyethylene terephthalate lamella after longitudinal stretching, which are capable after transversal stretching at 16O⁰C with a stretching factor of 3.5 of providing good quality layers with good adhesion to the polyester lamella include:

The polyester-urethane WAC-20 from Takamatsu Oil and Fat is also capable upon application as an aqueous dispersion to a polyethylene terephthalate lamella after longitudinal stretching, which is capable after transversal stretching at 16O⁰C with a stretching factor of 3.5 of providing good quality layers with good adhesion to the polyester lamella.

Layer system comprising a copolymer of a chlorinated ethylene According to a nineteenth embodiment of the security laminate, according to the present invention, said copolymer of a chlorinated ethylene comprised in said layer system is a copolymer of vinylidene chloride with at least one monomer selected from the group consisting of acrylic acid esters, methacrylic acid esters, methacrylic acid, acrylic acid, vinyl esters, acrylonitrile , methacrylonitrile, itaconic acid, fumaric acid and maleic acid.

According to a twentieth embodiment of the security laminate, according to the present invention, the copolymer of vinylidene chloride comprised in said layer system has a minimum film- forming temperature less than 50⁰C, with a film-forming temperature less than 35°C being preferred and a film-forming temperature less than 25°C being particularly preferred.

A wide range of VDC -copolymers is available from SOLVIN under the tradename DIOFAN as aqueous dispersions. Copolymers of vinylidene chloride with a concentration of vinylidene chloride greater than 88 wt% have a very strong tendency to crystallize. Moreover, incorporation of itaconic acid requires careful control of the copolymerization conditions.

Suitable copolymers of a chlorinated ethylene for use in the layer contiguous with the polyester lamella include:

a DIOFAN A658 from SOLVIN b DIOPAN A674 from SOLVIN c DIOFAN 080 from SOLVIN ^α DIOFAN A675 from SOLVIN e DIOFAN A676 from SOLVIN £ HALOFLEX 208 from ICI ## VC = vinyl chloride ** VDC = vinylidene chloride

# MA = methyl acrylate *** IA = itaconic acid

* BA = butyl acrylate

Surfactants and dispersants

According to an eighteenth embodiment of the security laminate, according to the present invention, said composition further comprises a surfactant, with an anionic or non- ionic surfactant being preferred.

According to a nineteenth embodiment of the security laminate, according to the present invention, said adhesion system further a surfactant, with an anionic or non- ionic surfactant being preferred.

Examples of suitable surfactants are:

Industrial application

The security laminates and adhesion systems, according to the present invention, can be used in identity documents such as driver's licenses, ID-cards and passports, and on other important documents such as certificates of title. Security laminates are also useful as tamper proof seals on medications, video cassettes, and compact discs.

The invention is illustrated hereinafter by way of COMPARATIVE EXAMPLES and INVENTION EXAMPLES. The percentages and ratios given in these examples are by weight unless otherwise indicated.

MEK methyl ethyl ketone

PAREZ RESIN^Ti a 80% solids melamine- formaldehyde resin from

707: AMERICAN CYANAMID;

HORDAMER™ 40% aqueous dispersion of polyethylene from HOECHST;

PE02

KIESELSOL a 36% aqueous dispersion of colloidal silica from

IOOF BAYER ;

MERSOLAT H an alkyl sulphonate surfactant from BAYER;

UCAR™ VAGD this solution vinyl resin being a hydroxyl- functional, partially-hydrolyzed vinyl chloride/ vinyl acetate resin from Dow Chemical Company.

PREPARATION OF ADHESION LAYERS ADHESION LAYERS prepared with COMPOSITION 1 on polyethylene terephthalate sheets:

A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched then coated with the COMPOSITION 1 given in Table 1:

Table 1 :

which after drying was transversally stretched to produce a 200μm thick sheet coated with a layer with the compositions, expressed as the coating weights of the ingredients present in the coating, given in Table 2 below:

Table 2 :

The resulting layer was transparent and glossy, whereas if coated on biaxially stretched 100 μm thick polyethylene terephthalate sheet (adhesion layer AO) an inhomogeneous layer with coloured spots was obtained.

ADHESION LAYERS prepared with COMPOSITION 2 on polyethylene terephthalate sheets: A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched then coated to different wet thicknesses with COMPOSITION 2 given in Table 3 :

Table 3 :

[wt %] de ioni zed water 87 . 3 188 copolymer CCE - 02 (used as a 30 % by weight aqueous 7 . 1023 di spersion)

KIESELSOL^® I O OF 5 . 5433

MERSOLAT H (used as a 3 . 7 wt% aqueous solution) 0 . 0356

which after drying was transversally stretched to produce 200 μm thick sheets coated with the compositions, expressed as the coating weights of the ingredients present, given in Table 4 below:

Table 4 :

The resulting layers were transparent and glossy, whereas if coated on biaxially stretched 100 μm thick polyethylene terephthalate sheet (adhesion layer BO) inhomogeneous layers with coloured spots were obtained.

Adhesion layers prepared with COMPOSITION 3 on polyethylene terephthalate sheets:

A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched then coated with COMPOSITION 3 given in Table 5 :

Table 5:

copolymer CCE-02 (used as a 30% by weight aqueous 14.2046 dispersion)

KIESELSOL^® IOOF 11 .0866

MERSOLAT H (used as a 3 .7 wt% aqueous solution) 0. 0712

which after drying was transversally stretched to produce a 200 μra thick sheet coated with a layer with the composition, expressed as the coating weights of the ingredients present, given in Table 6 below:

Table 6:

The resulting layer was transparent and glossy, whereas if coated on biaxially stretched 100 μm thick polyethylene terephthalate sheet

(adhesion layer DO) an inhomogeneous layer with coloured spots was obtained.

ADHESION LAYERS prepared with COMPOSITION 4 on polyethylene terephthalate sheets:

A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched then coated to different wet thicknesses with COMPOSITION 4 given in Table 7:

Table 7:

[wt%] deionized water 61 9564 copolymer CCE-02 (used as a 30% by weight aqueous 21 3069 dispersion)

KIESELSOL^® IOOF 16 6299

MERSOLAT H, an alkyl sulphonate surfactant from BAYER AG 0. 1068 (used as a 3.7 wt% aqueous solution)

which after drying was transversally stretched to produce a 200 μm thick sheet coated with respective layers with the compositions, expressed as the coacing weights of the ingredients present, given in Table 9 below:

Table 8 :

The resulting layers were transparent and glossy, whereas if coated on biaxially stretched 100 μm thick polyethylene terephthalate sheet (adhesion layer DO) inhomogeneous layers poor layer formation was observed.

ADHESION LAYERS prepared with COMPOSITION 5 on polyethylene terephthalate sheets:

A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched then coated with COMPOSITION 5 given in Table 9:

Table 9:

[wt%] deionized water 61.9564 copolymer CCE-03 (used as a 38% by weight aqueous 21.3069 dispersion)

KIESELSOL^® IOOF 16.6299

MERSOLAT H (used as a 3 .7 wt% aqueous solution) 0.1068

which after drying was transversally stretched to produce a 200μm thick sheet coated with the composition, expressed as the coating weights of the ingredients present, given in Table 10 below:

Table 10:

Coating thickness [μm] : ca. 0.9

The resulting layer was transparent and glossy, whereas if coated on biaxially stretched 100 μm thick polyethylene terephthalate sheet (adhesion layer EO) a bright layer with mat spots was obtained.

ADHESION LAYERS prepared with COMPOSITION 6 on polyethylene terephthalate sheets:

A 0.34 mm thick polyethylene terephthalate sheet was first longitudinally stretched then coated with COMPOSITION 6 given in Table 11:

Table 11:

[wt%] deionized water 87 . 3188 copolymer CCE- 04 (used as a 48 . 2 % by weight aqueous 7 . 1023 dispersion)

KIESELSOL^® IOOF 5 . 5433

MERSOLAT H (used as a 3 . 7 Wt % aqueous solution) 0 . 0356

which after drying was transversally stretched to produce a 200 μm thick sheet coated with the composition, expressed as the coating weights of the ingredients present, given in Table 12 below:

Table 12:

The resulting layer was matte, whereas if coated on biaxially stretched 100 μm thick polyethylene terephthalate sheet (adhesion layer HO) an inhomogeneous layers with colour spots was obtained.

ADHESION LAYERS prepared with COMPOSITION 7 on polyethylene terephthalate sheets : A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched then coated with COMPOSITION 7 given in Table 13 :

Table 13 :

[wt %] deioni zed water 23 . 9128 copolymer CCE- 04 (used as a 48 . 2 % by we ight aqueous 42 . 6138 di spersion)

KIESELSOL^® IO OF 33 . 2598

MERSOLAT H (used as a 3 . 7 wt % aqueous solution) 0 . 2136

which after drying was transversally stretched to produce a 200μm thick sheet coated with the composition, expressed as the coating weights of the ingredients present, given in Table 14 below:

Table 14:

The resulting layer was matte and not powdery, whereas if coated on biaxially stretched 100 μm thick polyethylene terephthalate sheet (adhesion layer GO) a matte powdery layer was obtained.

ADHESION LAYERS prepared with COMPOSITION 2 on polyethylene terephthalate sheets with subsequently applied additional identical layers :

A 63 μm thick biaxially stretched polyethylene terephthalate sheet with composition 2 applied between longitudinal stretching and transversal stetching to the same total coating weight as Bl, sample B6, was coated on one side with composition 2 (see Table 3) to wet layer thicknesses of lOμm, 20μm, 50μm and lOOμm respectively which after drying for 10 mins at 80⁰C produced layers Hl to H4 respectively on the B6 layer with the compositions given in Table 15, expressed as the coating weights of the ingredients present. Table 15 :

A second sheet was subjected to further drying for 10 minutes at HO⁰C instead of for 10 minutes at 8O⁰C giving samples HlA, H2A, H3A and H4A respoectively .

63 μm thick biaxially stretched polyethylene terephthalate sheets of type B6 were also further coated on one side with COMPOSITION 4 (see Table 7) to wet layer thicknesses of 10, 20, 50 and 100 μm respectively which after drying for 10 mins at 8O⁰C produced layers Jl to J4 respectively on the B6 layer with the compositions given in Table 16, expressed as the coating weights of the ingredients present.

Table 16:

A second sheet was subjected to further drying for 10 minutes at HO⁰C instead of for 10 minutes at 80⁰C giving samples JlA, J2A, J3A and J4A respoectively .

63 μm thick biaxially stretched polyethylene terephthalate sheets of type B6 were also further coated on one side with

COMPOSITION 5 (see Table 9) to wet layer thicknesses of 5, 10, 20 and 50 μm respectively which after drying for 10 mins at 80⁰C produced layers Kl to K4 respectively on the B6 layer with the compositions given in Table 17, expressed as the coating weights of the ingredients present.

Table 17:

A second sheet was subjected to further drying for 10 minutes at HO⁰C instead of for 10 minutes at 80⁰C giving samples KlA, K2A, K3A and K4A respectively.

ADHESION LAYERS prepared with COMPOSITION 2 on polyethylene terephthalate sheets with subsequently applied COMPOSITIONS 8 to 14: [V109/02]

63 μm thick biaxially stretched polyethylene terephthalate sheets of type B6 were coated on one side with COMPOSITION 8 to 14 given in Table 18 below:

Table 18:

Composition 8 9 10 11 12 13 14 deionized water [wt%] 68. 65 69 31 71 39 66 95 67 68 70 53 69 72 copolymer CCE-02 (used as 25. 80 27 . 86 28 42 26 48 29 00 26 21 29 13

which were dried under different conditions to produce the layers of L1-L9. M1-M9, N, P, Q, R and S1-S9. The compositions, drying temperatures and drying times are given in Table 19.

Table 19:

Overcoating of the ca. 12.9 μm thick adhesion layers of S1-S9 with COMPOSITION 22 resulted in a matte layer and overcoating of the ca. 5.3 μm thick adhesion layers of M1-M9 with COMPOSITION 22 resulted in a slightly matte layer.

ADHESION LAYERS prepared with COMPOSITION 2 on polyethylene terephthalate sheets with subsequently applied COMPOSITIONS 15 to 17:

63 μm thick biaxially stretched polyethylene terephthalate sheets of type B6 were coated on one side with COMPOSITION 15 to 17 given in Table 20 below:

Table 20:

Composition 15 16 17 de ioni zed water [wt%] 62 55 65 45 65 45 copolymer CCE- 02 (used as a 30% by weight 22 67 aqueous di spersion) [wt %] copolymer CCE - 05 (used as a 27 % by weight 20 92 aqueous dispersion) [wt%] copolymer CCE- 06 (used as a 27 % by weight 20 92 aqueous di spersion) [wt %]

KIESELSOL^® IO OF [wt%] 14 41 13 29 r i3 29

MERSOLAT H (used as a 3 . 7 wt % aqueous 0 . 37 0 . 34 0 . 34 solut ion) [wt %]

which were coated to different layer thicknesses and dried for 15 mins at HO⁰C to produce the layers of T1-T4, U1-U4 and V1-V4 respectively. The compositions are given in Table 21. Table 21 :

ADHESION LAYERS prepared with COMPOSITION 2 on polyethylene terephthalate sheets with subsequently applied COMPOSITIONS 18 to 21: [V109/02]

63 μm thick biaxially stretched polyethylene terephthalate sheets of type B6 were coated on one side with COMPOSITION 18 to 21 given in Table 22 below:

Table 22:

Composition 18 19 20 21 deionized water [wt%] 66 50 76.32 68 24 64 85 copolymer CCE- 02 (used as a 30% by 20 32 23.32 20 85 19 81 weight aqueous dispersion) [wt%]

KIESELSOL^® IOOF [wt%] 12 86 - 10 58 15 03

MERSOLAT H (used as a 3.7 wt% aqueous 0. 32 0.37 0. 33 0. 31 solution) [wt%]

COMPOSITION 18 was diluted for the coating of Samples W1-W6 and not for the coating of W7 to W9. COMPOSITIONS 19 and 21 were used undiluted for the coating of samples X, Y and Z. The compositions and drying conditions of the layers for Samples W1-W9, X, Y and Z are given in Table 23.

Table 23 :

* 50um wet thickness ** 35μm wet thickness # 25μm wet thickness

ADHESION LAYERS prepared with COMPOSITION 22 on polyethylene terephthalate sheets:

A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched to 330 μm thickness then coated to different wet thicknesses with COMPOSITION 22 given in Table 24:

Table 24:

KIESELSOL^® IOOF 16 6299

which after drying first in situ with a hair-dryer and then in a drying cupboard for 30 mins at 110⁰C was transversally stretched to produce a 200 μm thick sheet coated with respective layers with the compositions, expressed as the coating weights of the ingredients present, given in Table 25 below:

Table 25:

ADHESION LAYERS prepared with COMPOSITION 23 on polyethylene terephthalate sheets:

A 1100 μm thick polyethylene terephthalate sheet was first longitudinally stretched then coated with COMPOSITION 23 given in Table 26:

Table 26:

[wt%] deionized water 51 643 copolymer CCE- 03 (used as a 38% by weight aqueous 29 328 dispersion)

KIESELSOL^® IOOF 18 883

MERSOLAT H (used as a 3 .7 wt% aqueous solution) 0. 146

which after drying was transversally stretched to produce a lOOμm thick sheet coated with the composition, expressed as the coating weights of the ingredients present, given in Table 27 below:

Table 27:

ABl AB2 AB3 copolymer CCΞ-03 [mg/m²] : 8004.82 1212.85 151 colloidal silica (KIESELSOL™ IOOF) [mg/m² ] : 1855.42 281.12 35

Mersolat H [mg/m² ] : 39.76 6.024 0.75

SUPPLEMENTARY ADHESION LAYERS:

COMPOSITION 24, a composition for the coating of a supplementary adhesion layer is given in Table 28:

Table 26:

COMPOSITION 24 was coated with a wet layer thickness of 49 μm produced a layer with the following composition:

LAMINATION EXPERIMENTS

The adhesive system-coated side of the polyethylene terephthalate sheets was laminated with an EXECELAM 655Q laminator (from GMP Co. Ltd, Korea) at a temperature of 16O⁰C at speed position 1 and pressure position 1 between silicone paper with different polymer sheets: a 115 μm thick opaque polyvinyl chloride sheet, a 150 μm thick PETG sheet from Danneman, a 100 μm thick biaxially oriented PET sheet and a 30 μm thick polyethylene sheet from Bishoff und Klein. The other side of the polyethylene terephthalate sheets was laminated to a 200 μm thick PETG sheet to endow the laminate with rigidity. The delamination resistance of the laminates were evaluated using different tests: a preliminary dry peel strength evaluation, dry and wet peel strength according to ISO/IEC 7810:1995 with an Instron and corner impact and paint shaker tests according to ANSI INCITS 322-2002 Card Durability Test Methods. The initial evaluation of the dry peel strength, wet peel strength and the peel strength after the paint shaker test was carried out on the basis of the following criteria:

The laminates evaluated together with the test results are summarized in Table 27:

Table 27:

* resistance to further delamination

# after 5d 71°C/95% RH

** 125 μm polycarbonate from BAYER

The presence or absence of surfactant MERSOLAT H in the adhesion layers comprising a polyvinyl idene copolymer appears not to be critical for adhesion. However, the presence and concentration of colloidal silica in the adhesion layers comprising a polyvinyl idene copolymer appears to be critical for adhesion. Good dry peel strength results were obtained for layer systems with a thickness greater than 2.5 μm. The best adhesion results were obtained with the following layer systems: B6/J3A, B6/J4A, B6/K2, B6/K3, B6/K4, B6/L3, B6/L6, B6/L7, B6/L9, B6/M1, B6/M2, B6/M3, B6/M4, B6/M9, B6/R, B6/S4, B6/S6, B6/S7 and B6/S8 with layer system thicknesses between ca. 2.7 μm (for B6/L3, B6/L6, B6/L7 and B6/L9) and ca. 25.5 μm (for B6/J4A) .

It has been found for coating compositions based on latexes of copolymers of a chlorinated ethylene that, for a given coating weight, the more concentrated the polymer dispersion upon which the coating compositions are based the better the dry and wet peel strengths observed. Furthermore, for coating compositions based on latexes of a copolymer of a chlorinated ethylene better dry and wet peel strengths have been observed with latexes with higher molecular weights e.g. the layer thickness at which the same level of adhesion was observed was lower with the higher molecular weight vinylidene chloride -copolymer.

Good dry peel strength was observed with a 63 μm thick PET with a ca. 9 μm layer of a composition based on a copolymer of a chlorinated ethylene laminated to a polycarbonate ID- card. However, no adhesion was obtained upon laminating a 100 μm thick PET lamella with a ca. 9.9 μm layer of a similar composition based on a copolymer of a chlorinated ethylene laminated to a 125 μm thick polycarbonate lamella. The only difference in the layer based on a copolymer of a chlorinated ethylene between these experiments is that the layer in the case of the lamination to the polycarbonate ID- card was made up of part stretched during the transversal stretching of the PET lamella and part subsequently coated thereon, whereas in the case of the lamination to the polycarbonate lamella the layer was totally stretched during the transversal stretching of the PET- lamella, which could have given rise to weakness of the layer.

The situation with polycarbonate was replicated with the same PET- samples upon laminating a 30 μm thick polyethylene lamella.

However, an excellent dry peel strength was observed upon laminating a PET sample with a ca. 9.9 μm thick layer system based on a copolymer of a chlorinated ethylene to a 150 μm thick PETG lamella . The present invention may include any feature or combination of features disclosed herein either implicitly or explicitly or any generalisation thereof. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

[ CLAIMS]

1. A security laminate comprising at least one biaxially oriented polyester lamella and an adhesion system associated therewith

5 and on at least one side thereof, said adhesion system comprising a layer system comprising a polyester, a polyester- urethane or a copolymer of a chlorinated ethylene, said layer system being contiguous with said at least one biaxially oriented polyester lamella, wherein at least that part of saido layer system contiguous with said polyester lamella was contiguous with said polyester lamella during at least part of the biaxial orientation of said at least one polyester lamella and wherein said layer system has a thickness of at least 1.0 μm. 5

2. The security laminate according to claim 1, wherein said composition further comprises a copolymer latex of an optionally substituted divinyl olefin. 0

3. The security laminate according to claim 1 or 2 , wherein said security laminate comprises a security laminate precursor provided by lamination of said layer system with a lamella selected from the group consisting of an amorphous polyester lamella, a crystalline polyester lamella, a polycarbonates lamella, a polyolefin lamella and a polyvinyl chloride lamella.

4. The security laminate according to claim 3, wherein the wet peel strength of said security laminate precursor is at least 6 N/cm² as measured according to ISO Norm 10373-1-1978. 0

5. The security laminate according to any one of claims 1 to 4, wherein said security laminate is an identity document.

6. The security laminate according to any one of claims 1 to 5,5 wherein said security laminate is an identification card.

7. An adhesion system contiguous with a biaxially oriented polyester sheet, said adhesion system comprising a layer system comprising a polyester, a polyester-urethane or a copolymer of0 a chlorinated ethylene, said layer system being contiguous with said biaxially oriented polyester sheet, wherein at least that part of said layer system contiguous with said polyester lamella has been stretched during at least part of the biaxial orientation of said polyester sheet and wherein said layer system has a thickness of at least 1.0 μm.

8. A process for providing an adhesion system on at least one side of a biaxially oriented polyester sheet, said adhesion system comprising a layer system having a thickness of at least 1.0 μm contiguous therewith, said process comprising the steps of: biaxially stretching a polyester sheet with at least that part of said adhesion system contiguous with said polyester sheet being contiguous therewith during at least part of the biaxial stretching process, said part of said adhesion system contiguous with said polyester sheet being a layer having a composition comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene; and optionally applying a coating to said layer using conventional coating techniques, said layer and said optional coating being comprised in said layer system.

9. The process according to claim 8, wherein said step of biaxially stretching a polyester sheet with at least that part of said adhesion system contiguous with said polyester sheet being contiguous therewith during at least part of the biaxial stretching process orientation comprises the steps of: longitudinally stretching a polyester sheet; applying a composition comprising a polyester, a polyester-urethane or a copolymer of a chlorinated ethylene to said longitudinally- streched polyester sheet to provide a layer of said composition contiguous with said longitudinally- streched polyester sheet; and transversally stretching said longitudinally- stretched polyester sheet.