Coextruded foil composite material and its use in card bodies

Abstract

A composite film material usable in a data carrier card body includes a first outer plastic layer, an inner plastic layer and a second outer plastic layer, all the layers together forming a co-extruded composite. The plastic material of the first outer layer is a polyethylene terephthalate glycol copolymer (PETG) or contains a PETG, the plastic material of the inner layer is a thermoplastic elastomer (TPC) or containes a TPC, and the plastic material of the second outer layer is a PETG or contains a PETG.

Claims

1. A method for manufacturing a card body having a plurality of foil composite layers, comprising: a card core made of at least one inlay foil layer, at least two cover foil layers for covering both surfaces of the card core, and wherein the foil composite layers are laminated to each other in one work operation or in several work operations, wherein there is used as at least one of the cover foil layers and/or as the at least one inlay foil layer a foil composite material, wherein the foil composite material comprises: an inner layer formed between a first outer layer and a second outer layer, the first outer layer comprising terephthalate glycol copolymer (PETG), the second outer layer comprising PETG, the inner layer comprising a single thermoplastic copolyester elastomer (TPC) and being the thickest layer of the foil composite material.

2. The method according to claim 1, wherein laminating is effected at a temperature of between 120 C. and 200 C.

3. The method of claim 1, wherein the first outer layer, the second outer layer and the inner layer of the foil composite material being in the form of a coextrusion comprising: merging all the materials of the first outer layer, the second outer layer and the inner layer in a molten state, and extruding them through an extruder nozzle that extrudes a foil, to thereby obtain an extruded foil composite material.

4. The method according to claim 1, wherein the inlay foil layer has a thickness in the range of about 50 to 350 m.

5. The method according to claim 1, wherein the cover foil layers have a thickness in the range of about 80 to 130 m.

6. The method according to claim 1, wherein the foil composite material has a total layer thickness made up of 80 to 40% the inner layer and 10 to 30% the first and second outer layers.

7. The method according to claim 1, wherein between the at least one inlay foil layer and the cover foil layers there is located electronic components and imprinted antennas.

8. The method according to claim 1, wherein the card body has a total thickness of 0.5 to 1.0 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will hereinafter be illustrated further on the basis of Figures. It is pointed out that the figures are not true to proportion and not true to scale. Moreover, it is pointed out that the Figures are only intended to explain the invention more closely and are by no means to be understood as restrictive. The same reference numbers designate the same elements.

(2) There are shown:

(3) FIG. 1 a section through a foil composite material according to the invention having an inner plastic layer, two first outer plastic layers and two second outer plastic layers,

(4) FIG. 2 a section through a foil composite material according to the invention having an inner plastic layer which consists of an interior inner layer and two exterior inner layers, and having a first outer plastic layer and a second outer plastic layer,

(5) FIG. 3 a section through a foil composite material according to the invention having an inner plastic layer, a first outer plastic layer and a second outer plastic layer,

(6) FIG. 4 a section through a card body according to the invention having two foil composite materials according to the invention as cover layers,

(7) FIG. 5 a section through a card body according to the invention having two foil composite materials according to the invention as intermediate layers, and

(8) FIG. 6 a section through a card body according to the invention having two foil composite materials according to the invention as cover layers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

(9) FIG. 1 shows a first embodiment of a foil composite material 4 according to the invention. In the represented embodiment, the foil composite material has five layers, an inner plastic layer 3, a first outer plastic layer 1 and a second outer plastic layer 2, whereby the outer plastic layer 1 consists of an interior partial layer 11 and an exterior partial layer 12, and the outer plastic layer 2 consists of an interior partial layer 21 and an exterior partial layer 22. The inner layer 3 consists of 100% thermoplastic copolyester elastomer or a mixture of thermoplastic copolyester elastomers, and the first outer plastic layer 1 and the second outer plastic layer 2 consist of thermoplastic plastic material, whereby the two interior outer layers 11, 21 consist of 100% PETG, while the two exterior outer layers 12, 22, contain, in addition to PETG, an antiblocking agent, for example about 4 wt. % antiblocking agent, with the balance being PETG. The contents are always stated in wt. %.

(10) The manufacture of the foil composite material 4 can be effected for example by melting granules with three different compositions (granules A: 96% PETG+4% antiblocking agent; granules B: 100% PETG; granules C: 100% TPC) in three extruders A, B, C, and merging the corresponding molten streams (material A from extruder A, material B from extruder B, material C from extruder C) in a feedblock and jointly extruding them through a wide slot nozzle. In the represented embodiment, the foil composite material is symmetrical in construction, i.e. the interior outer layers 11, 21 and the exterior outer layers 12, 22 respectively have the same composition and the same thickness. This is not compulsory. Rather, the interior outer layers 11, 21 or the exterior outer layers 12, 22 can respectively differ from each other, for example contain different PETG, have a different thickness or have a different content of antiblocking agent. In such a case, correspondingly more extruders are necessary in a modified feedblock or wide slot nozzle arrangement. Preferably, however, the foil composite materials are symmetrically constructed, for reasons of an easier manufacturability, on the one hand, and since an unsymmetrical construction usually provides no advantages, on the other hand.

(11) In the represented embodiment, the inner plastic layer 3 is the thickest layer. This usually will actually be so in practice, since a proportion of TPC material as high as possible is desired, in order to achieve a high elasticity of the foil composite material 4. Exemplary layer thicknesses are respectively about 10% of the total thickness for the layers 12, 22, respectively 20% of the total layer thickness for the layers 11, 21, and about 40% of the total layer thickness for the layer 3.

(12) The following extruder settings achieved good results:

(13) TABLE-US-00001 Temperature [ C.] Feed zone [ C.] Extruder A 220-260 40-60 Extruder B 225-250 40-60 Extruder C 215-245 40-70 Nozzle 210-260

(14) The respective most favorable extruder settings can vary in dependence on the extruders employed (throughput, screw geometries or the employed materials and their residual moisture content). They provide information for orientation, which a person skilled in the art can optionally adapt to the given extruder configurations and given material facts by a few routine tests.

(15) FIG. 2 shows a different embodiment of a foil composite material 4 according to the invention in cross section. In this embodiment, the inner plastic layer consists of an interior partial layer 31 and two exterior partial layers 32, 33. Located thereon are a first outer plastic layer 1 and a second outer plastic layer 2. The inner layers 31, 32, 33 in turn consist of thermoplastic copolyester elastomer (TPC), whereby all inner layers can consist of the same TPC material or of different TPC materials. If desired, for one or several of the inner layers 31, 32, 33 there can also be employed a mixture of TPC materials, or a mixture of one or several TPC materials with a thermoplastic, for example PETG. In this way gradations can be produced, i.e. a gradual transition from, for example, a layer 31 made of 100% TPC material over a layer 32 or 33 made of TPC material with PETG admixture to a layer 1 or 2 made of 100% PETG. It is preferred, however, to use pure TPC material, in particular the same TPC material, for all inner layers 31, 32, 33. The special advantage of the present invention lies in the fact that upon using thermoplastic copolyester elastomers for the inner layers in combination with PETG for the outer layers, no compoundings are necessary for producing compatible transitions between the layers.

(16) The manufacture of the foil composite material 4 represented in FIG. 2 can be effected analogously to the foil composite material represented in FIG. 1. That is, in an extruder A for example a plastic material made of 96% PETG with 4% antiblocking agent is melted for the outer layers 1 and 2 and fed to a wide slot nozzle, and in two extruders B and C a plastic material made of 100% TPC is respectively melted and fed to the wide slot nozzle, whereby the feeding is effected such that the layer construction represented in FIG. 2 is produced. Extruder C, which extrudes the material for the thickest inner layer 31, must have the greatest flow rate. However, it is also possible that the extruder C does not have the greatest flow rate. The flow rate of the individual extruders can be generally adapted to the production conditions and to the specific requirements of the plastic material respectively used and the layer to be manufactured therewith.

(17) In the following there are stated exemplary extruder settings for manufacturing the foil composite material 4, which optionally are to be adapted to the extruder configurations and material moistures present in the respective individual case.

(18) TABLE-US-00002 Temperature [ C.] Feed zone [ C.] Extruder A 220-250 40-60 Extruder B 215-240 40-60 Extruder C 215-240 40-60 Nozzle 210-250

(19) For all embodiments and layer sequences of the foil composite material according to the invention it has proven to be particularly useful to use the following materials: Arnitel VT 3104 as a thermoplastic copolyester elastomer, Eastman PETG 6763 as a thermoplastic polymer, Release Sukano S 462 as an antiblocking agent.

(20) FIG. 3 shows a further embodiment of the foil composite material 4 according to the invention. This embodiment has the simplest layer construction with a single inner layer 3 made of TPC material and two outer layers 1, 2 made of PETG. One or several of the layers can contain, as in all other embodiments, usual accessory agents, for example dyes, UV protection agents or (in the outer layers) antiblocking agents. Antiblocking agents, however, are not absolutely necessary.

(21) Usually it is desired that the inner layer made of TPC material has an as great a proportion as possible in the total thickness of the foil composite material, so that the advantageous elasticity properties of the TPC material have a good effect. The outer layers 1, 2 made of PETG are usually kept thin because they are to serve for equipping the inner TPC layer(s) with the surface properties of the thermoplastic polymer PETG. Further, the outer layers 1, 2 are to provide the needed stiffness to the foil, so that this can be further processed in the common methods, such as e.g. for printing, handling etc. These properties are for example the good laminatability, handling without massive danger of blocking, good printability, etc. From this point of view, the layer thickness of the inner TPC layer should have a proportion of at least 40% in the total thickness of the foil composite material. Preferred are proportions of 60 to 80% TPC layer thickness in the foil material layer thickness. In order to be able to achieve these high layer thicknesses, the inner TPC layer is composed of several partial layers usually with the help of several extruders.

(22) It is in principle possible that both the outer plastic layers 1, 2 and the inner plastic layer 3 are respectively composed of several partial layers. Simultaneously, however, it is preferred that the foil composite material 4 produced has no more than seven partial layers, since the coextrusion is more difficult in terms of process engineering, the more partial layers have to be coextruded with each other. Therefore, preferably either the inner layer 3 or the outer layers 1, 2 consist of partial layers, whereby the outer layers respectively should be constructed from no more than two partial layers, and the inner layer should be constructed from no more than five, preferably no more than three, partial layers.

(23) FIGS. 4, 5 and 6 respectively show exemplary layer constructions for card bodies 5 according to the invention (exploded views). In general, card bodies according to the invention consist of a card core 9 which is typically constructed from one to seven layers. The layers consist of thermoplastic foils, typically made of PVC, ABS, polyester, polycarbonate, PEC (blend of PC and one or several other polyesters) and the like. Between the layers and/or in recesses of the layers there can be located electronic components such as electronic modules and antennas. Other features, such as for example security elements or imprints, can also be provided. The layer construction is respectively completed on the outer side by a cover layer. The foils forming the layer construction are preferably interconnected by laminating, which is why all materials used should be readily laminatable to each other.

(24) FIG. 4 shows an embodiment of a card body 5 according to the invention having a card core 9, consisting of a PET foil 60 (152 m), onto which, optionally, a coil (not shown) can be imprinted, and two PVC foils 61, 62 (240 m each). The layer construction is completed by the two cover foils 80, 81 (105 m each), which consist of the foil composite material 4 according to the invention, as was described hereinabove.

(25) FIG. 5 shows another embodiment of a card body 5 according to the invention. Here, the card core 9 consists of a single PET foil 60 (152 m) having an imprinted antenna (not shown). The PET foil 60 is adjoined on both sides by the layers 70, 71 (240 m each). The layers 70, 71 in this embodiment consist of the foil composite material 4 according to the invention. The layer construction is completed by the two cover layers 80, 81 made of a PETG overlay foil (105 m each).

(26) A further alternative embodiment for a card body 5 according to the invention is represented in FIG. 6. Here, the card core 9 consists of the PETG foils 60, 61 (310 m each), onto which the cover layers 80, 81 (105 m each) are laminated. The cover layers 80, 81 consist of the foil composite material 4 according to the invention.

(27) In FIGS. 4, 5 and 6, the m-values in brackets respectively denote the thicknesses. It goes without saying that the specified layer thicknesses as well as the specified materials are to be understood only by way of example, and that other materials which are laminatable to each other as well as deviating layer thicknesses and deviating numbers of layers can also be used. Further, the card constructions are represented symmetrically in the Figures, which, however, is by no means compulsory. Essential is, that the foil composite material 4 according to the invention can be both used as a cover layer, as shown in FIG. 4 and FIG. 6, and as an intermediate layer, as shown in FIG. 5. Embodiments are also possible wherein the foil composite material 4 according to the invention is used only as one of the cover layers and/or as an intermediate layer, and embodiments which have cover layers and intermediate layers which are both made of the foil composite material 4 according to the invention. Upon use as a cover layer (overlay foil), the layer thickness of the foil composite material 4 is typically no more than half as thick as upon a use as an intermediate layer (inlay foil). As a cover layer the foil composite material according to the invention is preferably transparent, while as an intermediate layer it is preferably opaque.

(28) Through the employment of the foil composite material according to the invention as cover layer(s) and/or as intermediate layer(s) in a card body, the mechanical properties of card bodies can be decisively improved over card bodies of the prior art. The card bodies can be subjected to stronger and more frequent bending loads without there occurring stresses, cracks or breaks of the card body. Stresses arising from the installation of electronic modules, which always cause a weakening of the card body, can also be compensated and thus the mechanical properties of the card body improved. The foil composite material according to the invention can be employed in the card bodies instead of any standard foil. It is itself highly flexible and gives the card bodies flexibility.

(29) In particular card constructions wherein the foil composite material according to the invention is employed as an intermediate layer, as represented by way of example in FIG. 5, have excellent mechanical properties, such as excellent strength and stiffness. This becomes evident particularly in the case of actions of impact force, which otherwise as a rule lead to card breakage. This is presumably caused by the greater thickness of the foil composite material intermediate layers, and thus the higher proportion of the foil composite material according to the invention in the card body altogether.

(30) The foil composite material according to the invention is also very stable in itself, i.e. there is a firm bond between the partial layers made of PETG and thermoplastic copolyester elastomer without any danger of the partial layers separating from each other upon load. This stability can be achieved without producing gradations between the partial layers by the use of material mixtures. Therefore there is no need for producing compoundings of granules upon the coextrusion.

(31) The foil composite material according to the invention can be manufactured inexpensively, and there is a wide spectrum of thermoplastic copolyester elastomers with different properties available on the market. The foil composite material made of PETG and thermoplastic copolyester elastomers is easier to process by the coextrusion method than foils with other thermoplastic elastomers. It is also characterized by especially simple handling in further processing, i.e. it can for example be printed without any problems and laminated to all common card materials. It also does not tend to block. A special advantage that makes the foil composite material according to the invention excellently suitable in particular for use as a layer in a card body, is the act that the foil composite material can be manufactured with a very high proportion of thermoplastic elastomer, thereby improving the mechanical properties of the card body in an excellent manner.