PLASTIC FILMS HAVING HIGH OPACITY AND LOW TRANSPARENCY FOR ID DOCUMENTS HAVING A TRANSPARENT WINDOW

Abstract

The present invention relates to a layered composite comprising at least one transparent layer a) containing a thermoplastic, this transparent layer having a light transmission in the range of from ≥85% to ≤98% determined according to ISO 13468-2:2006-07, and an opaque layer b) containing at least one thermoplastic, characterised in that the opaque layer b) has a light transmission in the range of from ≥0.1% to ≤25% determined according to ISO 13468-2:2006-07, a layer thickness in the range of from ≥20 μm to ≤70 μm, preferably from ≥20 μm to ≤60 μm, particularly preferably from ≥25 μm to ≤55 μm, and at least one opening.

Claims

1. A multi-layer film comprising at least a) a transparent layer a) containing a thermoplastic, wherein the transparent layer has a light transmission in a range from ≥85% to ≤98% determined according to ISO 13468-2:2006-07; and b) an opaque layer b) containing at least one thermoplastic, wherein the opaque layer b) has a light transmission in a range from ≥0.1% to ≤25% determined according to ISO 13468-2:2006-07, a layer thickness in a range from ≥20 μm to ≤70 μm, and has at least one opening.

2. The multi-layer film as claimed in claim 1, further comprising at least one further transparent layer c) containing a thermoplastic and having a light transmission in a range from ≥85% to ≤98% determined according to ISO 13468-2:2006-07, wherein the layer c) is identical to or different from layer a) and is arranged such that a layer sequence a) b) c) results in the multi-layer film.

3. The multi-layer film as claimed in claim 1, wherein layer b) contains at least one filler.

4. The multi-layer film as claimed in claim 1, wherein layers a), layer b) optionally a further transparent layer c), or a combination thereof independently of one another comprise at least one thermoplastic selected from the group consisting of a polymer of ethylenically unsaturated monomers a polycondensates of bifunctional reactive compounds, and combinations thereof.

5. The multi-layer film as claimed in claim 1, wherein the at least one opening in layer b) is not additionally filled with a thermoplastic material.

6. The multi-layer film as claimed in claim 1, wherein layer a), layer b), optionally a further transparent layer c), or a combination thereof comprises a laser-sensitive additive.

7. The multi-layer film as claimed in claim 1, wherein the layer a) has a thickness of ≥30 to ≤800 μm.

8. The multi-layer film as claimed in claim 2, wherein the at least one layer c) has a thickness of ≥30 to ≤700 μm.

9. The multi-layer film as claimed in claim 1, wherein the opening has a shape selected from the group consisting of star-shaped, square, triangular, rectangular, head-shaped, and a combination of at least two thereof.

10. The multi-layer film as claimed in claim 1, wherein the opening in layer b) is introduced into layer b) by means of laser radiation.

11. A process for producing a multi-layer film comprising providing at least one multi-layer film construction as claimed in claim 1, optionally providing further layers comprising at least one thermoplastic, optionally applying security features in such a way that layer b) at least partially covers these security features, laminating the multi-layer film construction at a temperature of 120° C. to 210° C. ° C. to and a pressure of 10 N/cm.sup.2 to 400 N/cm.sup.2.

12. The process as claimed in claim 11, wherein the multi-layer film construction is inscribed by laser radiation before and/or after lamination.

13. The process as claimed in claim 11, wherein the opening in layer b) is introduced into layer b) by laser radiation.

14. A security document, comprising at least one multi-layer film construction as claimed in claim 1.

15. A method of producing a window in a security document, comprising preparing a security document comprising an opaque layer comprising at least one thermoplastic, said opaque layer having a light transmission in a range from ≥0.1% to ≤25% determined according to ISO 13468-2:2006-07 and having a layer thickness in a range from ≥20 μm to ≤70 μm.

16. The multi-layer film as claimed in claim 4, wherein the at least one thermoplastic is selected from the group consisting of: one or more polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates, poly- or copolymers of styrene, polyurethanes, polyolefins, poly- or copolycondensates of terephthalic acid, poly- or copolycondensates of naphthalenedicarboxylic acid, poly- or copolycondensates of at least one cycloalkyldicarboxylic acid, polysulfones, and mixtures thereof.

17. The multi-layer film as claimed in claim 4, wherein the at least one thermoplastic is selected from the group consisting of: one or more polycarbonates or copolycarbonates based on diphenols, blends containing at least one polycarbonate, and copolycarbonate.

Description

EXAMPLES

[0094] Raw Materials Employed:

[0095] Makrolon™ 3108: high-viscosity, amorphous thermoplastic bisphenol A polycarbonate having an MVR of 6 g/10 min according to ISO 1133-1:2011 at 300° C. and 1.2 kg of applied weight from Covestro AG.

[0096] KRONOS™ 2230: titanium dioxide from Kronos for polycarbonate and other industrial thermoplastics having a TiO.sub.2 content ≥96%

Example 1: Compounding a Masterbatch for Production of the Layer Containing a Thermoplastic and a White Pigment as Filler

[0097] Production of the masterbatch for production of a white layer was carried out with a conventional twin-screw compounding extruder (ZSK 32) at processing temperatures customary for polycarbonate of 250° C. to 330° C.

[0098] A masterbatch having the following composition was compounded and subsequently granulated: [0099] 70% by weight of Makrolon™ 3108 polycarbonate [0100] 30% by weight of Kronos™ 2230 (titanium dioxide) as white pigment filler.

[0101] General Production Procedure for Extrusion Films

[0102] The employed apparatus consists of [0103] an extruder having a screw of 105 mm in diameter (D) and a length of 41×D. The screw has a devolatilization zone; [0104] a crosshead; [0105] a slot die of 1500 mm in width; [0106] a three-roll smoothing calendar with horizontal roller orientation, wherein the third roller can swivel by +/−45° relative to the horizontal; [0107] a roller conveyor; [0108] an apparatus for double-sided application of protective film; [0109] a haul-off apparatus; [0110] a winding station.

[0111] The pellet material was supplied to the extruder hopper. The respective material was melted and conveyed in the respective barrel/screw plasticizing system. The material melt was supplied to the nozzle. The melt passed from the nozzle onto the smoothing calendar. On the smoothing calendar the material is subjected to final shaping and cooling. Structuring of the film surfaces was achieved using a matted steel roller (no. 4 surface) and a matted rubber roller (no. 4 surface). The film was subsequently transported through a haul-off and then the film was wound up. The corresponding white opaque extrusion films were produced in this way according to table 1.

TABLE-US-00001 TABLE 1 White opaque films Compound Layer thickness Example 2 100% compound from example 1  30 μm Example 3  50% compound from example 1;  30 μm (noninventive)  50% Makrolon ™ 3108 Example 4 100% compound from example 1  50 μm Example 5  50% compound from example 1 + 100 μm (noninventive)  50% Makrolon ™ 3108

[0112] Light Transmission and Breaking Elongation of the White Opaque Films

[0113] Thin films are particularly sensitive to agglomerates, i.e. non-homogeneously distributed titanium dioxide. The dispersion of the titanium dioxide in the film and the homogeneity of the film thickness were assessed visually and the light transmission of the films determined. The dispersion of the titanium dioxide in the film and the mechanical strength may further be assessed by determining breaking elongation.

[0114] Light transmission was determined according to ISO 13468-2:2006-07 using a Byk Haze Gard Plus measuring instrument. Tensile tests were performed according to ISO 527-1:1996. The tensile rod type employed was ISO 527-1:1996 type 1B.

TABLE-US-00002 TABLE 2 Light transmission and breaking elongation of the white opaque films Light transmission Breaking elongation Film % DR % Example 2 9.5  60.9 Example 3 34.3 not determined (noninventive) Example 4 8.5 101.8 Example 5 8.8 not determined (noninventive)

[0115] Production of Identification Documents (ID Card) Having Transparent Window

[0116] Films for the Layer Construction:

[0117] Films of Examples 2-5

[0118] Example 6: A polycarbonate film of 100 μm in thickness was produced as described hereinabove from Makrolon™ 3108 polycarbonate by extrusion at a melt temperature of about 280° C. Structuring of the film surfaces was achieved using a matted steel roller (no. 6 surface) and a matted rubber roller (no. 2 surface).

[0119] Example 7: A film as per film 6 was produced but with a thickness of 540 μm.

[0120] Stamped into each of the white opaque films was a hole of 10 mm in diameter and, next to it, a second hole of 20 mm in diameter.

[0121] Layer constructions according to table 3 were produced. A symmetrical layer construction of the card was selected to avoid bending of the card. To this end, respective stacks were formed from the films in the orders shown in table 3 and lamination was carried out with the following parameters on a Bürkle lamination press.

[0122] Conditions [0123] Preheating the press to 170-180° C. [0124] pressing for 8 minutes at a pressure of 15 N/cm.sup.2 [0125] pressing for 2 minutes at a pressure of 200 N/cm.sup.2 [0126] cooling the press to 38° C. and opening the press.

TABLE-US-00003 TABLE 3 Layer construction of the ID cards having a transparent window Layer (1) Layer (2) Layer (3) Layer (2) Layer (1) Exam- Example 6 Example 2 Example 7 Example 2 Example 6 ple 8 (100 μm)  (30 μm) (540 μm)  (30 μm)  100 μm Exam- Example 6 Example 3* Example 7 Example 3* Example 6 ple 9 * (100 μm)  (30 μm) (540 μm)  (30 μm) (100 μm) Exam- Example 6 Example 4 Example 7 Example 4 Example 6 ple 10 (100 μm)  (50 μm) (540 μm)  (50 μm) (100 μm) Exam- Example 6 Example 5* Example 7 Example 5* Example 6 ple 11* (100 μm) (100 μm) (540 μm) (100 μm) (100 μm) * noninventive

[0127] The openings in the films of the layers (2) were each arranged symmetrically in the film stack.

[0128] Results of the Laminations

[0129] For all cards opacity was assessed visually and the stamping of the round transparent window was assessed for air bubbles and sink marks.

[0130] In noninventive example 11 a sink mark in the region of the transparent window and also an air bubble were apparent. This defect was avoidable only by inserting a transparent filler material prior to lamination. This results in increased complexity in the production of ID documents.

[0131] Both laminates of examples 8 and 10 according to the invention exhibited no sink marks and no bubble formation and so flawless laminate quality was obtainable. In addition, light transmission was very low due to the high opacity of the films. To the extent that printed images, antennae or IC chips are incorporated into the layer construction these are not apparent in the laminates according to the invention.

[0132] No sink marks and no bubble formation were observable in noninventive example 9 but the laminate from example 9 had a high light transmission. As a result of the high light transmission, printed images, antennae or IC chips may therefore be apparent to the extent these are incorporated into the layer construction.