PLASTIC FILMS FOR ID DOCUMENTS WITH BETTER LIGHTNESS OF EMBOSSED HOLOGRAMS

Abstract

The present invention relates to a layered structure containing at least one layer (i) comprising a thermoplastic material and at least one further layer (ii) comprising a thermoplastic material bearing at least one embossed hologram, to a process for producing such layer composites and to security documents, in particular identification documents, having the layered structure according to the invention.

Claims

1. A layered structure containing at least one layer (i) comprising a thermoplastic material and at least one further layer (ii) comprising a thermoplastic material, wherein the vicat softening temperature B/50 of layer (i) as determined according to ISO 306 at 50N and 50/h is 3 C. to 45 C., preferably 10 C. to 40 C., particularly preferably 15 C. to 30 C., higher or lower than the softening temperature of layer (ii) and in that at least one embossed hologram is applied to the layer (i) or (ii) such that the nanostructure of the at least one embossed hologram points in the direction of the layer having the lower softening temperature.

2. The layered structure as claimed in claim 1, wherein the layers (i) and/or (ii) comprise monofilms and/or multilayer films.

3. The layered structure as claimed in claim 1, wherein the thermoplastic material of the at least one layer (i) and the at least one further layer (ii) is at least one plastic selected from polymers of ethylenically unsaturated monomers and/or polycondensates of difunctional reactive compounds and/or polyaddition products of difunctional reactive compounds or mixtures thereof.

4. The layered structure as claimed in claim 1, wherein the thermoplastic material of the layers (i) and (ii) is selected from the group of polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates, preferably polymethyl methacrylates (PMMA), poly- or copolymers with styrene, preferably polystyrene (PS) or polystyrene acrylonitrile (SAN), thermoplastic polyurethanes and polyolefins, preferably, polypropylene types or polyolefins based on cyclic olefins, poly- or copolycondensates of an aromatic dicarboxylic acid and aliphatic, cycloalophatic and/or araliphatic diols having 2 to 16 carbon atoms, preferably poly- or copolycondensates of terephthalic acid, particularly preferably poly- or copolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG), glycol-modified poly- or copolycyclohexanedimethylene terephthalate (PCTG) or poly- or copolybutylene terephthalate (PBT or CoPBT), preferably poly- or copolycondensates of naphthalenedicarboxylic acid, particularly preferably polyethylene glycol naphthalate (PEN), poly- or copolycondensate(s) of at least one cycloalkyldicarboxylic acid, for example and preferably polycyclohexanedimethanolcyclohexanedicarboxylic acid (PCCD), polysulfones (PSU), polyvinyl halides, preferably polyvinyl chloride (PVC), or mixtures of the abovementioned.

5. The layered structure as claimed in claim 1, wherein the thermoplastic material of the layers (i) and (ii) is selected from the group of polycarbonates or copolycarbonates based on diphenols, poly- or copolycondensates of an aromatic dicarboxylic acid and aliphatic, cycloalophatic and/or araliphatic diols having 2 to 16 carbon atoms, preferably poly- or copolycondensates of terephthalic acid, particularly preferably poly- or copolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG), glycol-modified poly- or copolycyclohexanedimethylene terephthalate (PCTG) or poly- or copolybutylene terephthalate (PBT or CoPBT), preferably poly- or copolycondensates of naphthalenedicarboxylic acid, particularly preferably polyethylene glycol naphthalate (PEN), poly- or copolycondensate(s) of at least one cycloalkyldicarboxylic acid, preferably polycyclohexanedimethanolcyclohexanedicarboxylic acid (PCCD), polysulfones (PSU), polyvinyl halides, preferably polyvinyl chloride (PVC), or mixtures of the abovementioned.

6. The layered structure as claimed in claim 1, wherein at least one layer (i) or (ii) comprises a thermoplastic material comprising a) at least one or more poly- or copolycondensate(s) of an aromatic and/or cycloalkyldicarboxylic acid and aliphatic, cycloaliphatic and/or araliphatic diols having 2 to 16 carbon atoms, wherein the poly- or copolycondensate(s) of an aromatic and/or cycloalkyldicarboxylic acid and aliphatic, cycloaliphatic and/or araliphatic diols having 2 to 16 carbon atoms comprise a proportion of 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and/or 2,2,4,4-tetramethyl-1,3-cyclobutanediol in a range from 20 to 80 mol % based on the diol component, b) a blend of at least one or more poly- or copolycondensate (s) of an aromatic and/or cycloalkyldicarboxylic acid and aliphatic, cycloaliphatic and/or araliphatic diols having 2 to 16 carbon atoms with one or more poly- or copolycarbonate(s), wherein the proportion of poly- or copolycarbonate-(s) in this blend is in a range from 0% by weight to 90% by weight, preferably 0% by weight to 80% by weight, and wherein the poly- or copolycondensate(s) of an aromatic and/or cycloalkyldicarboxylic acid and aliphatic, cycloaliphatic and/or araliphatic diols having 2 to 16 carbon atoms comprise a proportion of 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol and/or 2,2,4,4-tetramethyl-1,3-cyclobutanediol in a range from 20 to 80 mol %, preferably in a range from 25 to 75 mol %, particularly preferably in a range from 25 to 70 mol %, based on the diol component, or c) a blend of poly- or copolycarbonates containing difunctional carbonate structural units of formula (II) ##STR00008## wherein R.sup.1 and R.sup.2 independently of one another represent hydrogen, halogen, preferably chlorine or bromine, C.sub.1-C.sub.8-alkyl, C.sub.5-C.sub.6-cycloalkyl, C.sub.6-C.sub.10-aryl, preferably phenyl, and C.sub.7-C.sub.12-aralkyl, preferably phenyl-C.sub.1-C.sub.4-alkyl, in particular benzyl, m is an integer from 4 to 7, preferably 4 or 5, R.sup.3 and R.sup.4 individually selectable for each X independently of one another represent hydrogen or C.sub.1-C.sub.6-alkyl, X represents carbon and n is an integer greater than 20, with the proviso that for at least one atom X, R.sup.3 and R.sup.4 both represent alkyl.

7. The layered structure as claimed in claim 6, wherein the further layer (i) or (ii) comprises a thermoplastic material from the group of polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates, for example and preferably polymethyl methacrylate (PMMA), poly- or copolymers with styrene, for example and preferably polystyrene (PS) or polystyrene acrylonitrile (SAN), thermoplastic polyurethanes and polyolefins, for example and preferably, polypropylene types or polyolefins based on cyclic olefins, poly- or copolycondensates of an aromatic dicarboxylic acid and aliphatic, cycloalophatic and/or araliphatic diols having 2 to 16 carbon atoms, for example and preferably poly- or copolycondensates of terephthalic acid, particularly preferably poly- or copolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG), glycol-modified poly- or copolycyclohexanedimethylene terephthalate (PCTG) or poly- or copolybutylene terephthalate (PBT or CoPBT), preferably poly- or copolycondensates of naphthalenedicarboxylic acid, particularly preferably polyethylene glycol naphthalate (PEN), poly- or copolycondensate(s) of at least one cycloalkyldicarboxylic acid, for example and preferably polycyclohexanedimethanolcyclohexanedicarboxylic acid (PCCD), polysulfones (PSU), polyvinyl halides, for example and preferably polyvinyl chloride (PVC), or mixtures of the abovementioned, particularly preferably polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates, for example polymethyl methacrylate (PMMA), poly- or co-polycondensates of terephthalic acid, for example poly- or copolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG), glycol-modified poly- or copolycyclohexanedimethylene terephthalate (PCTG), poly- or copolybutylene terephthalate (PBT or CoPBT), poly- or copolycondensates of naphthalenedicarboxylic acid, for example polyethylene glycol naphthalate (PEN), polyvinyl halides, for example polyvinyl chloride (PVC), very particularly preferably at least one polycarbonate or copolycarbonate.

8. The layered structure as claimed in claim 1, wherein the at least one layer (i) and the at least one further layer (ii) each have a layer thickness in the range from 20 to 200 m, preferably in the range from 25 to 145 m, very particularly preferably in the range from 30 to 120 m.

9. The layered structure as claimed in claim 1, wherein at least one layer (i) and/or (ii) comprises a laser-sensitive additive, preferably a black pigment, particularly preferably carbon black.

10. The layered structure as claimed in claim 9, wherein the laser-sensitive additive is present in this layer in an amount of 40 to 180 ppm.

11. A process for producing a layered structure as claimed in claim 1, comprising: A) applying at least one embossed hologram to a layer (i) or (ii) in such a way that the nanostructure of the at least one embossed hologram points in the direction of the layer having the lower softening temperature, wherein the layers (i) or (ii) each comprise a thermoplastic material and wherein the vicat softening temperature B/50 determined according to ISO 306 (50N; 50/h) of the layer (i) is 3 C. to 45 C., preferably 10 C. to 40 C., particularly preferably 15 C. to 30 C., higher or lower than the softening temperature of the layer (ii), b) optionally providing one or more further layers of a thermoplastic material, preferably polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates, for example and preferably polymethyl methacrylate (PMMA), poly- or copolymers with styrene, for example and preferably polystyrene (PS) or polystyrene acrylonitrile (SAN), thermoplastic polyurethanes and polyolefins, for example and preferably, polypropylene types or polyolefins based on cyclic olefins, poly- or copolycondensates of an aromatic dicarboxylic acid and aliphatic, cycloalophatic and/or araliphatic diols having 2 to 16 carbon atoms, for example and preferably poly- or copolycondensates of terephthalic acid, particularly preferably poly- or copolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG), glycol-modified poly- or copolycyclohexanedimethylene terephthalate (PCTG) or poly- or copolybutylene terephthalate (PBT or CoPBT), preferably poly- or copolycondensates of naphthalenedicarboxylic acid, particularly preferably polyethylene glycol naphthalate (PEN), poly- or copolycondensate(s) of at least one cycloalkyldicarboxylic acid, for example and preferably polycyclohexanedimethanolcyclohexanedicarboxylic acid (PCCD), polysulfones (PSU), polyvinyl halides, for example and preferably polyvinyl chloride (PVC), or mixtures of the abovementioned, particularly preferably polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates, for example polymethyl methacrylate (PMMA), poly- or co-polycondensates of terephthalic acid, for example poly- or copolyethylene terephthalate (PET or CoPET), glycol-modified PET (PETG), glycol-modified poly- or copolycyclohexanedimethylene terephthalate (PCTG), poly- or copolybutylene terephthalate (PBT or CoPBT), poly- or copolycondensates of naphthalenedicarboxylic acid, for example polyethylene glycol naphthalate (PEN), polyvinyl halides, for example polyvinyl chloride (PVC). c) placing the layers (i) and (ii) at the desired position in the layered structure, wherein the layers (i) and (ii) preferably form outer layers of the layered structure which may optionally be provided with a further protective layer of a thermoplastic material. d) laminating the layered structure at a temperature of 120 C. to 210 C., preferably of 130 C. to 205 C., particularly preferably of 150 C. to 200 C., and a pressure of 10 N/cm.sup.2 to 400 N/cm.sup.2, preferably of 30 N/cm.sup.2 to 300 N/cm.sup.2, particularly preferably of 40 N/cm.sup.2 to 250 N/cm.sup.2.

12. A security document, preferably identification document, comprising at least one layered structure as claimed in claim 1.

13. A laminate comprising a layered structure as claimed in claim 1.

14. (canceled)

15. (canceled)

Description

EXAMPLES

Raw Materials Employed:

[0136] Makrolon 3108 (M.3108): high-viscosity, amorphous thermoplastic bisphenol A polycarbonate having an MVR of 6 g/10 min according to ISO 1133 at 300 C. and 1.2 kg from Covestro AG.

[0137] Eastar DN 010 (DN 010): Poly- or copolycondensate of terephthalic acid composed of 54.9% by weight of terephthalic acid, 9.3% by weight (38 mol % based on diol component) of ethylene glycol and 35.8% by weight (62 mol % based on diol component) of cyclohexane-1,4-dimethanol having an inherent viscosity of 0.74 dl/g (measured in a 1:1 mixture of phenol and tetrachloroethane at 25 C.) from Eastman Chemical Company.

[0138] Pocan B 1600 (PBT 1600): Unmodified polycondensate of terephthalic acid and 1,4-butanediol as the diol component having a melt volume rate (MVR) of 14 g/10 min according to ISO 1133 at 260 C. and 2.16 kg from Lanxess AG.

Raw Material 1: Production of a Polycarbonate Derivative

[0139] 205.7 g (0.90 mol) of bisphenol A (2,2-bis(4-hydroxyphenyl)propane), 30.7 g (0.10 mol) of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 336.6 g (6 mol) of KOH and 2700 g of water are dissolved with stirring in an inert gas atmosphere. A solution of 1.88 g of phenol in 2500 ml of methylene chloride is then added. 198 g (2 mol) of phosgene were introduced into the well-stirred solution at pH 13 to 14 and 21 C. to 25 C. 1 ml of ethylpiperidine is then added and the mixture is stirred for 45 min. The bisphenoxide-free aqueous phase is removed, the organic phase is acidified with phosphoric acid, neutralized by washing with water and freed of solvent.

[0140] The polycarbonate derivative A showed a vicat softening temperature B/50 determined according to ISO 306 (50N; 50/h) of 183 C.

General Production Procedure for Extrusion Films

[0141] The employed apparatus consists of [0142] an extruder having a screw of 105 mm in diameter (D) and a length of 41D. The screw has a devolatilization zone; [0143] a crosshead; [0144] an extrusion slot die of 1500 mm in width; [0145] a three-roll smoothing calender with horizontal roller orientation, wherein the third roller can swivel by +/45 relative to the horizontal; [0146] a roller conveyor; [0147] an apparatus for double-sided application of protective film; [0148] a extraction device; [0149] a winding station.

[0150] The pelletized material was supplied to the extruder hopper. Melting and conveying of the material was carried out in the barrel/screw plasticizing system. The melt passed from the die onto the smoothing calender. On the smoothing calender the material is subjected to final shaping and cooling. Structuring of the film surfaces was achieved using a matt steel roller (no. 6 surface) and a finely matted rubber roller (no. 2 surface). The film was then transported through an extraction device before being wound up. The compositions of the films in the examples are described in table 1.

TABLE-US-00001 TABLE 1 Composition of extrusion films (examples 1 to 2) Melting VST/B/50 Formulation temperature (ISO 306) Film 1 M.3108 80% 260 C. 126 C. 100 m mono- DN 010 14.3% film, transparent PBT 1600 5.7% Film 2 Raw 100% 330 C. 183 C. 100 m mono- material 1 film, transparent Film 3 M.3108 100% 280 C. 148 C. 100 m mono- film, transparent

[0151] Film 4: Polyester film having embossed hologram and adhesive layer on the non-embossed side of the polyester film, from Krypten. The total thickness of the film was 23 m.

[0152] Film 5: 22 m polyester carrier film having a separation layer, having a metal layer and an adhesive layer that is applied to the side of the separation layer. The metal layer is vapor-deposited onto the polyester carrier film having a separation layer by vacuum metallization. The adhesive coating is subsequently applied to the metallized side of the film. The adhesive layer is a 1 m thin adhesive layer of a heat-activatable adhesive.

Production of Layered Structures

Example 1

[0153] Application of the Hologram onto Film 3 [0154] Film 4 was glued to the finely matted side (no. 2 side) of film 3 and the nanostructure was applied to film 4 such that this nanostructure faces away from film 3. Film 3 and film 4 were bonded by roller lamination having the following parameters. Temperature of rollers: 150 C. [0155] Pressure: 5 N/cm2 [0156] Lamination speed: 1 meter/minute

Layered Structure 1:

[0157] Film 1 was placed on the film composite of film 3 and film 4, with its finely matted side (no. 2 side) in contact with film 4 (FIG. 1). This layered structure was laminated in a Brkle lamination press with the following parameters:

preheating the press to 190 C. [0158] pressing for 4 minutes at a pressure of 15 N/cm.sup.2 [0159] pressing for 1 minute at a pressure of 200 N/cm.sup.2 [0160] cooling the press to 38 C., opening the press and removing the laminate.

Example 2 (Comparative)

[0161] A further layered structure 2 was produced analogously to example 1 but with the exception that film 3 was used instead of film 1 (FIG. 2)

[0162] Visual assessment of the laminates 1 and 2 clearly showed that the embossed holograms in the inventive laminate 1 exhibit a better brightness. In addition, the details of the depicted shapes and the light refraction of the embossed hologram were virtually unchanged.

Example 3

[0163] On the finely matted side (no. 2 side) of film 2, nanogravures are embossed into the film surface by hot embossing. Prior to the embossing process a thin metal layer is vapor-deposited onto the embossing stamp in a thickness of just a few nanometers by vacuum metallization. The embossing stamp has a special coating to prevent permanent adhesion of the metal layer to the stamp. At the site at which the embossing is to be effected the film is provided with a thin layer of a heat-activatable adhesive, namely with the adhesive of the type 532380 from Apollo Inks

[0164] The embossing process of the film is carried out in a vacuum chamber to allow continuous metallization of the embossing stamp and with the following embossing parameters described:

[0165] Temperature of embossing stamp: 210 C.

[0166] Embossing pressure: 500 N/cm.sup.2

[0167] Embossing time: 1.5 s.

Layered Structure 3:

[0168] Film 3 is placed with its finely matted side (no. 2 side) onto the embossed finely matted side (no. 2 side) of film 2 in contact with film 2 (FIG. 3). The lamination of the layered structure was carried out on a Brkle lamination press with the following parameters:

preheating the press to 190 C. [0169] pressing for 4 minutes at a pressure of 15 N/cm.sup.2 [0170] pressing for 1 minute at a pressure of 200 N/cm.sup.2 [0171] cooling the press to 38 C., opening the press and removing the laminate.

Example 4 (Comparative)

[0172] A further layered structure 4 is produced analogously to example 3 but with the exception that film 3 is used instead of film 2 (FIG. 4).

[0173] Visual assessment of the laminates 3 and 4 clearly shows that the embossed holograms in the inventive laminate 3 exhibit a better brightness. The details of the depicted shapes and the light refraction of the embossed hologram were virtually unchanged.

Example 5

[0174] Film 5 is bonded to the finely matted side (no. 2 side) of film 2 and fixed by roller lamination according to the following parameters: [0175] Temperature of rollers: 150 C. [0176] Pressure: 5 N/cm2 [0177] Lamination speed: 1 m/minute

[0178] The 22 m-thick carrier film of film 5 is subsequently removed.

[0179] The embossing of the hologram in film 2 is carried out on the side comprising the transferred adhesive and metal layer from film 5 according to the following embossing parameters: [0180] Temperature of embossing stamp: 210 C. [0181] Embossing pressure: 500 N/cm.sup.2 [0182] Embossing time: 1.5 s.

Layered Structure 5:

[0183] Film 3 is placed with its finely matted side (no. 2 side) onto the embossed film 2 in contact with film 5 (FIG. 5). This layered structure is laminated on a Brkle lamination press with the following parameters:

preheating the press to 190 C. [0184] pressing for 4 minutes at a pressure of 15 N/cm.sup.2 [0185] pressing for 1 minute at a pressure of 200 N/cm.sup.2 [0186] cooling the press to 38 C., opening the press and removing the laminate.

Example 6 (Comparative)

[0187] A layered structure 6 is produced analogously to example 5 but with the exception that film 3 is used instead of film 2 (FIG. 6)

[0188] Visual assessment of the laminates 5 and 6 clearly shows that the embossed holograms in the inventive laminate 5 exhibit a better brightness. The details of the depicted shapes and the light refraction of the embossed hologram were virtually unchanged.

Example 7

[0189] An embossed hologram is applied to film 3 as described at example 1.

Layered Structure 7:

[0190] An adhesive layer of the heat-activatable adhesive Chemipearl V200 from Mitsui Chemicals was applied by screen printing onto the film composite of film 3 and 4, namely onto the side of the embossed hologram of film 4 in a layer thickness of about 3 m (FIG. 7). A further film 1 was placed on the adhesive layer so that the finely matted side (no. 2 side) of film 1 was in contact with the adhesive layer. This layered structure was laminated on a Brkle lamination press with the parameters reported at example 1.

Example 8 (Comparative)

[0191] A further layered structure 8 was produced as described at example 7 but with the exception that film 3 was used instead of film 1 (FIG. 8).

[0192] Visual assessment of the laminates from examples 7 and 8 clearly showed that the embossed holograms in the inventive laminate from example 7 exhibit a better brightness. In addition, the details of the depicted shapes and the light refraction of the embossed hologram were virtually unchanged. The presence of an adhesive layer between the embossed hologram and the film 1 or 3 has no effect on the appearance of the embossed hologram.

[0193] FIGS. 1 to 8 show schematic diagrams of the layered structure of laminates 1 to 8 with the films employed in each case. The numerals on the left-hand side of the individual film layers indicate the surface structure of the corresponding film: Structuring of the film surfaces was achieved using a matt steel roller (no. 6 surface) and a finely matted rubber roller (no. 2 surface).