Plastic films for ID documents having improved properties for laser engraving and improved chemical resistance

Abstract

The present invention relates to plastic films with improved laser engraving capability, chemical resistance and mechanical stress, special embodiments of such films in the form of co-extrusion films, layer structures comprising such films, use of such films, as well as security documents, preferably identification documents, containing such films.

Claims

1. A film comprising at least one layer (i) containing at least one blend from at least one or several poly or co-polycondensate(s) of an aromatic and/or a cycloalkyl dicarbonic acid and aliphatic, cycloaliphatic and/or araliphatic dials with 2 to 16 carbon atoms with one or several poly or co-polycarbonates(s), and at least one laser-sensitive additive, wherein the portion of poly or co-polycarbonates(s) in the blend lies in a range from ≥50 wt.- % to ≤90 wt. - % and wherein the poly or co-polycondensate(s) of an aromatic and/or a cycloalkyl dicarbonic acid and aliphatic, cycloaliphatic and/or araliphatic dials with 2 to 16 carbon atoms have a portion of 1,4-cyclohexane dimethanol, 1,3-cyclohexane dimethanol and/or 2,2,4,4-tetramethyl-1,3-cyclobutanediol in a range from ≥20 to ≤80 mol % related to the diol components, wherein the laser-sensitive additive is a black pigment, in a quantity of from 40 to 180 ppm.

2. The film as claimed in claim 1, wherein the black pigment is carbon black.

3. The film as claimed in claim 1, wherein the aromatic and/or cycloalkyl dicarbonic acid comprises at least one compound selected from the group consisting of orthophthalic acid, teraphthalic acid, isophthalic acid, tert butylisophthalic acid, 3,3′-diphenyl dicarbonic acid, 4,4′-diphenyl dicarbonic acid, 4,4-benzophenone dicarbonic acid, 3,4′-benzophenone dicarbonic acid, 4,4′-diphenyl ether dicarbonic acid, 4,4′-diphenyl sulfone dicarbonic acid, 2,2-bis (4-carboxyphenyl)-propane, trimethyl-3-phenyl lindane-4,5′-dicarbonic acid, napthalene-1,4-dicarbonic acid, napthalene-1,5-dicarbonic acid, napthalene-2,6-dicarbonic acid, cyclohexane dicarbonic acid, and a reactive derivative of teraphthalic acid mentioned, napthalene-1,4-dicarbonic acid, napthalene-1,5-dicarbonic acid, napthalene-2,6-dicarbonic acid, isophthalic acid.

4. The film as claimed in claim 1, wherein the blend from at least one or several poly or co-polycondensate(s) of an aromatic and/or a cycloalkyl dicarbonic acid and aliphatic, cycloaliphatic and/or araliphatic dials with 2 to 16 carbon atoms with one or several poly or co-polycarbonates(s) comprises a blend from poly or co-polybutylene teraphthalate and/or glycol-modified poly or co-poly cyclohexylene dimethylene teraphthalate, provided that the portion of poly or co-polycarbonates(s) in this blend lies in a range from ≥50 wt.- % to ≤90 wt.- %, and wherein the poly or the co-polyterephthalate has a portion of 1,4-cyclohexane dimethanol, 1,3-cyclohexane dimethanol and/or tetramethyl-1,3-cyclobutanediol, in a range from ≥20 to ≤80 mol %, related to the dial components.

5. The film as claimed in claim 1, wherein the film comprises a further layer (ii) and this further layer contains one or several poly or co-polycondensate(s) of an aromatic and/or a cycloalkyl dicarbonic acid and aliphatic, cycloaliphatic and/or araliphatic dials with 2 to 16 carbon atoms.

6. The film as claimed in claim 5, wherein the film comprises a third layer (iii), this third layer comprising one or several poly or co-polycondensate(s) of an aromatic and/or a cycloalkyl dicarbonic acid and aliphatic, cycloaliphatic and/or araliphatic dials with 2 to 16 carbon atoms and the layers being arranged so that the two layers (ii) and (iii) form the outer layers of the film.

7. The film as claimed in claim 6, wherein the layer (ii) and/or the layer (iii) is free from poly and/or co-polycarbonate.

8. The film as claimed in claim 6, wherein the layer (ii) and/or the layer (iii) has a portion of 1,4-cyclohexane dimethanol, 1,3-cyclohexane dimethanol and/or 2,2,4,4-tetramethyl-1,3-butanediol, preferably 1,4-cyclohexane dimethanol and/or 1,3-cyclohexane dimethanol, in a range from ≥20 to ≤80 mol %, related to the dial components of one or several poly or co-polycondesate(s) of an aromatic and/or a cycloalkyl dicarbonic acid and aliphatic, cycloaliphatic and/or araliphatic dials with 2 to 16 carbon atoms.

9. The film as claimed in claim 1, wherein the film has a total coating thickness in the range of ≥30 to ≤145 μm.

10. The film as claimed in claim 6, wherein the outer layers ii) and iii) are the same in their composition.

11. The film as claimed in claim 5, wherein the film is produced by means of coextrusion.

12. A layer structure, comprising at least one film as claimed in claim 1.

13. A security document, containing at least one film as claimed in claim 1.

14. A method comprising utilizing the film as claimed in claim 1 as surface layer in a security document.

15. The film as claimed in claim 1, wherein the film has a surface resistance of from 10.sup.7 to 10.sup.13Ω determined in accordance with DIN IEC 60093 (1993).

Description

EXAMPLES

(1) Raw Materials Used:

(2) Makrolon™ 3108 (M.3108): Very viscous amorphous, thermoplastic bisphenol A-polycarbonate with an MVR of 6 g/10 min according to ISO 1133 at 300° C. and 1.2 kg supplied by Covestro AG

(3) Eastar™ DN 010 (DN 010): Poly or co-polycondensate of a teraphthalic acid from 54.9 wt.-% teraphthalic acid, 9.3 wt.-% (38 mol % related to the diol components) ethylene glycol and 35.8 wt.-% (62 mol % related to the diol components) cyclohexane dimethanol-1,4, with an inherent viscosity of 0.74 dl/g (measured in a 1:1 mixture from phenol and tetrachlorethane at 25° C.) supplied by the Eastman Chemical company.

(4) Eastar™ GN 001 (GN 001): Poly or co-polycondensate of a teraphthalic acid from 60.2 wt.-% teraphthalic acid, 18.0 wt.-% (65 mol % related to the diol components) ethylene glycol, 1.5 wt.-% diethylene glycol (3 mol % related to the diol components) and 20.3 wt.-% (32 mol % related to the diol components) cyclohexane dimethanol-1,4, with an inherent viscosity of 0.74 dl/g (measured in a 1:1 mixture from phenol and tetrachlorethane at 25° C.) supplied by the Eastman Chemical company.

(5) Pocan™ B 1600 (PBT 1600): Unmodified polycondensation product of the teraphthalic acid and butanediol-1,4 as diol components with a melt rate of 14 g/10 min according to ISO 1133 at 260° C. and 2.16 kg supplied by Lanxess AG.

(6) Pentacard™ PVC M 278/01 (PVC laserable): Laser writable PVC film supplied by the Klöckner company Pentaplast in a thickness of 100 μm.

(7) Pentacard™ PETG MG0ST00 (PETG laserable): Laser writable PETG film supplied by the Klöckner company Pentaplast in a thickness of 150 μm, polycondensation product of a teraphthalic acid from 60.6 wt.-% (100 mol % related to the diol components) teraphthalic acid, 18.8 wt.-% ethane diol and 20.6 wt.-% cyclohexane dimethanol-1,4 with an inherent viscosity of >/=0.78 dL/g.

(8) Pentacard™ PETG (white core film) (PETG white): White opaque tinted PETG film supplied by the Klöckner company Pentaplast in a thickness of 300 μm for card cores.

(9) Pentacard™ PVC (white core film) (PVC white): White opaque tinted PVC film supplied by the Klöckner company Pentaplast in a thickness of 280 μm for card cores.

(10) Master Batch 1: Compounding of a Highly Concentrated Master Batch Containing a Laser-Sensitive Additive

(11) The production of the master batch was used for the production of the laserable layer(s), took place with a conventional twin-screw compounder extruder (ZSK 32) at processing temperatures usual for polycarbonate from 250 to 330° C.

(12) A master batch with the following composition was compounded and then granulated: 99.9 wt.-% Makrolon™ 3108 polycarbonate 0.1 wt.-% (1000 ppm) lamp black 101 (carbon black supplied by the Degussa company) with average particle size of 95 nm.

(13) Master Batch 2: Compounding of a Master Batch Containing a White Pigment as Filler

(14) The production of the master batch for the production of a white layer took place with a conventional twin-screw compounder extruder (ZSK 32) at processing temperatures usual for polycarbonate from 250 to 330° C.

(15) A master batch with the following composition was compounded and then granulated: 70 wt.-% Makrolon™ 3108 polycarbonate 30 wt.-% titanium dioxide (Kronos™ 2230 supplied by the Kronos Titanium company) as white pigment filler.

(16) Master Batch 3: Compounding of a Master Batch Containing a Laser-Sensitive Additive

(17) The production of the master batch was used for the production of the laserable layer(s), took place with a conventional twin-screw compounder extruder (ZSK 32) at processing temperatures usual for polycarbonate from 250 to 330° C.

(18) A master batch with the following composition was compounded and then granulated: 99.994 wt.-% Makrolon™ 3108 polycarbonate 0.006 wt.-% (60 ppm). Lamp black 101 (carbon black supplied by the Degussa company) with average particle size of 95 nm

(19) General Production Standard for Extrusion and Co-Extrusion Films

(20) The plant used consists of an extruder with a screw of 105 mm in diameter (D) and a length of 41×D. The screw has a degassing zone; a coextruder for applying the surface layer with a screw of the length 25 D and a diameter of 35 mm a reversing head; a special coextrusion nozzle 1500 mm in width; a triple roller polishing calendar with horizontal roller arrangement, whereby the third roller is tiltable by +/−45° relative to the horizontal; a roller race; a machine for reciprocal application of protective plastic film; a take-off machine; a spooling station.

(21) Granulates of the base material were fed to the main extrusion hopper. Melting and conveying of the respective material took place in the respective cylinder/screw plastifier system. Both material melts came together in the coextrusion nozzle. The melt arrived at the polishing calendar from the nozzle. Final shaping and cooling of the material took place on the polishing calendar. Two polished chrome rollers (1st and 1st surface) were used for structuring the film surfaces. Subsequently the film was transported by a take off machine, the protective plastic film applied on both sides, and afterwards the film was spooled.

(22) The compositions of the example films are described in tables 1 and 2.

(23) TABLE-US-00001 TABLE 1 composition of the single layer extrusion films (examples 1 to 4) Recipe Melt temperature Example 1 M.3108 65% 260° C. 50 μm mono film, DN 010 25% transparent, not PBT 1600 10% laserable Example 2 M.3108 47% 260° C. 50 μm mono film, Master batch 3 18% transparent, DN 010 25% laserable PBT 1600 10% Example 3 M.3108 54% 260° C. 100 μm mono Master batch 3 11% film, transparent, DN 010 25% laserable PBT 1600 10% Example 4 M.3108 15% 260° C. 100 and 200 μm Master batch 2 50% mono film, white DN 010 25% opaque, not PBT 1600 10% laserable

(24) TABLE-US-00002 TABLE 2 composition of the triple layer co-extrusion films (examples 5 to 8) Thickness Thickness Thickness Layer (ii) [μm] Layer (i) [μm] Layer (iii) [μm] Example 5 100 wt. 20 82 wt.-% M.3108 18 60 100% wt-% 20 (comparison) % GN wt % master batch 3 GN 001 001 11 ppm laser-sensitive additive Example 6 100 wt. 10 90 wt.-% M.3108 30 100 wt.-% 10 (comparison) % GN 10 wt.-% master GN 001 001 batch 1 100 ppm laser- sensitive additive Example 7 100 wt. 10 95 wt.-% M.3108 5 30 100 wt.-% 10 (comparison) % GN wt.-% master batch 1 Eastar GN 001 001 50 ppm laser-sensitive additive Example 8 100 wt. 10 55 wt.-% M.3108 30 100 wt.-% 10 % GN 25 wt.-% DN 010 GN 001 001 10 wt.-% PBT 1600 10 % master batch 1 100 ppm laser- sensitive additive

(25) Production of Laser-Writable Identification Documents (ID Card)

(26) Films used for the ID card layer structure (beside the films of examples 1 to 8):

(27) Film 1-1: White Filled Film for the Core of the Card Structure

(28) A polycarbonate film 300 μm thick of Makrolon™ 3108 polycarbonate and master batch 2 in the ratio 1:1 was made at a mass temperature of approx. 280° C. by means of extrusion.

(29) Film 1-2: White Filled Film for the Core of the Card Structure

(30) A film with the same composition as film 1-1 of thickness 350 μm was produced.

(31) Film 2; Transparent Film as Non-Laserable Overlay Film

(32) A polycarbonate film of thickness 50 μm was produced on the basis of Makrolon™ 3108 polycarbonate at a mass temperature of approx. 280° C. by means of extrusion.

(33) The laser-writable ID-documents were laminated as follows in accordance with the layer structure of tables 3 and 4:

(34) A symmetrical layer structure of the card was selected, in order to avoid bending of the card. In addition a pile in the sequence specified above was formed from the films and the lamination was carried out in each case on a laminating press of the Bürkle company with the following parameters. Card structures under the laminating conditions A and B were produced:

(35) Conditions A Preheating the press to 170-180° C. Pressing for 8 minutes at a pressure of 15 N/cm.sup.2 Pressing for 2 minutes at a pressure of 200 N/cm.sup.2 Cooling of the press to 38° C. and opening of the press.

(36) Conditions B

(37) Preheating the press to 155° C. Pressing for 8 minutes at a pressure of 15 N/cm.sup.2 Pressing for 2 minutes at a pressure of 200 N/cm.sup.2 Cooling of the press to 38° C. and opening of the press.

(38) TABLE-US-00003 TABLE 3 Layer structure of the ID cards from films of examples 1 to 8: ID-3 ID-4 ID-1 ID-2 (comparison) (comparison) Layer (1) 50 μm film 100 μm film 100 μm PETG 100 μm PVC ex. 2 ex. 3 laserable laserable Layer (3) 700 μm film 600 μm film PETG white PVC white (core ex. 4 (2 × 350 ex. 4 (2 × 300 (2 × 300 μm) 2 × 280 μm layer) μm ex. 4) μm ex. 4) Layer 50 μm film 100 μm film 100 μm PETG 100 μm PVC (1′) ex. 2 ex. 3 laserable) laserable Ex.: Example

(39) TABLE-US-00004 TABLE 4 Layer structure of the ID cards from films of examples 5 to 8: ID-5 ID-6 ID-7 (comparison) (comparison) (comparison) ID-8 Layer (1) 100 μm film 50 μm film 50 μm film 50 μm film ex. 5 ex. 6 ex. 7 ex. 8 Layer (3) 600 μm 700 μm 700 μm 700 μm film core layer film 1-1 film 1-2 film 1-2 1-2 (2 × 350 (2 × 300 μm) (2 × 350 μm) (2 × 350 μm) μm) Layer (1′) 100 μm film 50 μm film 50 μm film 50 μm film ex. 5 ex. 6 ex. 7 ex. 8 Ex.: Example

(40) Results of the Laminations

(41) All cards could be laminated under the condition A in a bulge-free manner. The laminates could also already be laminated at 155° C. (condition B). A very good adhesion of the films of examples 1, 2 and 3 to the inlay film example 4, but in addition to the films 1-1 or 1-2 was obtained. The laminates of the comparison examples ID-3 and ID-4 were laminated with the same material in the core.

(42) For examining the stability of the ID cards, card bending tests were carried out in accordance with ISO/IEC 7810 AMD 2 (2012) and ISO/IEC 10373-1 AMD 1 (2012) with the corresponding ID cards. The results are given in tables 5 and 6.

(43) TABLE-US-00005 TABLE 5 Results of the card bending tests with artificial skin oil (supplied by Wfk Testgewebe GmbH, Germany) and acetone of examples ID-1 to ID-4 ID-3 ID-4 ID-1 ID-2 (comparison) (comparison) Alternate bending 20000 25000 15000 11500 cycles (skin oil) Alternate bending 17500 17500 14000 <15000 cycles (acetone)

(44) TABLE-US-00006 TABLE 6 Results of the card bending tests with artificial skin oil (supplied by Wfk Testgewebe GmbH, Germany) and acetone of examples ID-5 to ID-8 ID-5 ID-6 ID-7 (comparison) (comparison) (comparison) ID-8 Alternate bending 20000 17500 17500 17500 cycles (skin oil) Alternate bending 25000 25000 25000 25000 cycles (acetone)

(45) Laser Engraving of the Laser-Writable Identification Documents ID-1 to ID-8

(46) On the ID cards a laser engraving was carried out on a laser machine made by the Foba company with the following parameters:

(47) Laser medium: Nd:YAG

(48) Wave-length: 1064 nm

(49) Power: 40 Watt

(50) Current: 30 Amp

(51) Pulse frequency: 14 KHz

(52) Feed rate: 200 mm/sec

(53) During the laser engraving the information was only written on one of the laser-writable film layers of the ID card. As information a greyscale wedge was written by means of laser engraving into the laser-writable layer.

(54) FIG. 1 shows the intensity of the black colouring dependent on the intensity of the laser power during the laser printing of the ID cards containing single-layer films (ID-1 to ID-4). The cards of the comparison versions ID-3 and ID-4 showed a non pure-white basic colouring and remained very pale with little colour intensity in its contrast when written by laser. In comparison to this cards ID-1 and ID-2 according to the invention were pure white, high-contrast and intensely black in their colouring when written by laser.

(55) FIG. 2 shows the intensity of the black colouring dependent on the intensity of the laser power during the laser printing of the ID cards containing multi-layer films (ID-5 to ID-8). ID-5 on the one hand showed decreased laser engraving capacity and clearly worse contrasts than the card according to the invention ID-8. Although ID-6 (comparison) and ID-7 (comparison) showed good laser printing, the black colouring reached the saturation region too soon, so that differentiation is no longer possible in the laser-marked region. It is however particularly disadvantageous that the basic colouring of the card is too much (too grey). In FIG. 2 this effect is demonstrated by a high grey value as zero value.