PLASTIC FILMS HAVING HIGH VICAT SOFTENING TEMPERATURE IN LAYERED STRUCTURES

Abstract

The present invention relates to layer composites comprising at least one opaque layer a) and at least one transparent layer b), wherein the Vicat softening temperature B/120 determined according to ISO 306:2004 (method B120 50N; 120° C.) of layer a) is ≥156° C., preferably from ≥156° C. to ≤250° C., particularly preferably from ≥156° C. to ≤230° C., and wherein the Vicat softening temperature B/120 determined according to ISO 306:2004 (method B120 50N; 120° C./h), of layer a) is higher than that of layer b), a method for producing such layer composites and security documents, preferably identification documents, comprising such a layer structure.

Claims

1. A layer construction comprising a) at least a one opaque layer a) containing one or more polycarbonates or copolycarbonates based on diphenols, wherein the at least one layer a) has a light transmission of ≥0.1% and ≤85%, determined according to ISO 13468-2:2006-07 and b) at least east one further transparent layer b) containing at least one thermoplastic, wherein the at least one further layer b) has a light transmission of ≥85% and ≤98%, determined according to ISO 13468-2:2006-07, wherein the one or more polycarbonates or copolycarbonates of layer a) have a Vicat softening temperature B/120 determined according to ISO 306:2004 (method B120 50N; 120° C./h) of ≥156° C., and wherein the Vicat softening temperature of the one or more polycarbonates or copolycaronates of layer a) is higher a Vicat softening temperature of the thermoplastic of layer b).

2. The layer construction as claimed in claim 1, wherein the at least one layer b) comprises a thermoplastic having a Vicat softening temperature of B/120 determined according to ISO 306 (50N; 50° /h) in a range from ≥135° C. to ≤155° C.

3. The layer construction as claimed in claim 1, wherein the one or more polycarbonates or copolycarbonates based on diphenols in the at least one layer a) comprise at least one carbonate structural unit of formula (I-1), (I-2), (I-3) or (I-4) ##STR00007## wherein R.sup.1 and R.sup.2 independently of one another represent hydrogen, halogen, C.sub.1-C.sub.8-alkyl, C.sub.5-C.sub.6-cycloalkyl, C.sub.6-C.sub.10-aryl, or C.sub.7-C.sub.12-aralkyl, m is an integer from 4 to 7, 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, and X represents carbon, with the provision that for at least one atom X, R.sup.3 and R.sup.4 both represent alkyl, ##STR00008## wherein R.sup.5 represents a C.sub.1- to C.sub.4-alkyl radical, aralkyl radical or aryl radical.

4. The layer construction as claimed in claim 3, wherein in the at least one layer a) the one or more polycarbonates or copolycarbonates based on diphenols comprises at least one carbonate structural unit of formula (I-1).

5. The layer construction as claimed in claim 1, wherein the at least one layer a) comprises at least one opening.

6. The layer construction as claimed in claim 1, wherein the at least one layer a) comprises a filler.

7. The layer construction as claimed in claim 1, wherein the at least one layer a) has a thickness of ≥10 to ≤300 μm.

8. The layer construction as claimed in claim 1, wherein the at least one layer b) comprises at least one thermoplastic selected from polymers of ethylenically unsaturated monomers and/or polycondensates of bifunctional reactive compounds.

9. The layer construction as claimed in claim 1, further comprising at least one further layer c) comprising at least one thermoplastic, the at least one further layer c) having a light transmission of ≥85% to ≤98%, determined according to ISO 13468-2:2006-07.

10. The layer construction as claimed in claim 1, further comprising at least one further layer c) containing one or more polycarbonates or copolycarbonates based on diphenols.

11. The layer construction as claimed in claim 1, further comprising at least one laser sensitive additive present in one or more of the at least one layer a), the at least one layer b), or at least one further layer c).

12. The layer construction as claimed in claim 1, wherein at least one electronic component, at last one volume hologram, at least one embossed hologram, or a combination thereof is arranged between the at least one layer a) and the at least one layer b).

13. A process for producing a layer composite comprising providing a layer construction as claimed in claim 1, optionally placing one or more electronic components, one or more volume holograms, one or more embossed holograms, or a combination thereof between the at least one layer a) and the at least one layer b), optionally stamping at least one opening in layer a), optionally providing at least one further layer c) comprising at least one thermoplastic, laminating the layer construction at a temperature of 120° C. to 210° C. and a pressure of 10 N/cm.sup.2 to 400 N/cm.sup.2.

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

15. A method of producing a window in a security document, comprising forming a security document from a layered construction comprising an opaque layer a) containing one or more polycarbonates or copolycarbonates based on diphenols having a light transmission of ≥0.1% and ≤85%, determined according to ISO 13468-2:2006-07, wherein the one or more polycarbonates or copolycarbonates of layer a) have a Vicat softening temperature B/120 determined according to ISO 306:2004 (method B120 50N; 120° C./h) of ≥156° C.

16. The layer construction as claimed in claim 8, wherein the at least one thermoplastic comprises one or more polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylates and poly- or copolymethacrylates, poly- or copolymers of styrene, polyurethane(s) and polyolefin(s), poly- or copolycondensates of terephthalic acid, poly- or copolycondensates of naphthalenedicarboxylic acid, poly- or copolycondensates of at least one cycloalkyldicarboxylic acid, polysulfones, or mixtures thereof.

Description

EXAMPLES

Raw Materials Used

[0117] Makrolon™ 3108: high-viscosity amorphous thermoplastic bisphenol A polycarbonate from Covestro AG having an MVR of 6.5 g/10 min according to ISO 1133-1:2011 at 300° C. and 1.2 kg loading and a Vicat softening temperature (VST) according to ISO 306:2004 method B120 at 50 N; 120° C./h of 150° C. and a glass transition temperature T.sub.g according to ISO 11357-1,-2 of 149° C.

[0118] KRONOS™ 2230: titanium dioxide from Kronos for polycarbonate and other industrial thermoplastics having a TiO.sub.2 content ≥96%

Polycarbonate PC 1:

[0119] 149.0 g (0.65 mol) of bisphenol A (2,2-bis(4-hydroxyphenyl)propane), 107.9 g (0.35 mol) of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 336.6 g (6 mol) of KOH and 2700 g of water were dissolved with stirring in an inert gas atmosphere. A solution of 1.88 g of phenol in 2500 ml of methylene chloride was 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 was then added and the mixture stirred for 45 min. The bisphenoxide-free aqueous phase was removed and the organic phase acidified with phosphoric acid, neutralized by washing with water and freed of solvent. The polycarbonate showed a relative solution viscosity of 1.255 determined according to DIN EN ISO 1628-1:2009. The Vicat softening temperature of the polymer was determined as 183° C. according to ISO 306:2004 method B120 at 50 N; 120° C./h.

Polycarbonate PC 2:

[0120] Analogously to PC 1 a mixture of 91.6 g (0.40 mol) of bisphenol A and 185.9 g (0.60 mol) of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane was converted into the corresponding polycar-bonate 2. The polycarbonate showed a relative solution viscosity of 1.251 determined according to DIN EN ISO 1628-1:2009.

[0121] The Vicat softening temperature of the polymer was determined as 204° C. according to ISO 306:2004 method B120 at 50 N; 120° C./h.

Polycarbonate PC 3:

[0122] Analogously to PC 1 a mixture of 44.2 g (0.19 mol) of bisphenol A and 250.4 g (0.81 mol) of 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane was converted into the corresponding polycarbonate.

[0123] The polycarbonate showed a relative solution viscosity of 1.248 determined according to DIN EN ISO 1628-1:2009.

[0124] The Vicat softening temperature of the polymer was determined as 216° C. according to ISO 306:2004 method B120 at 50 N; 120° C./h.

Compounding a Batch for Production of a Layer Comprising a Thermoplastic and a White Pigment as Filler:

[0125] Production of the batches 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.

[0126] Batches were compounded with the compositions according to table 1 and subsequently pelletized:

TABLE-US-00001 TABLE 1 Composition of compounds for production of layers comprising thermoplastics Polycarbonate Kronos ™ 2230 Compound 1 85% by weight PC 1 10% by weight Compound 2 85% by weight PC 2 10% by weight Compound 3 85% by weight PC 3 10% by weight Compound 4 85% by weight Makrolon ™ 10% by weight 3108

General Production Procedure for Extrusion Films

[0127] The employed apparatus consists of [0128] an extruder having a screw of 105 mm in diameter (D) and a length of 41xD. The screw has a devolatilization zone; [0129] a crosshead; [0130] a slot die of 1500 mm in width; [0131] a three-roll smoothing calendar with horizontal roller orientation, wherein the third roller can swivel by +/−45° relative to the horizontal; [0132] a roller conveyor; [0133] an apparatus for double-sided application of protective film; [0134] a haul-off apparatus; [0135] a winding station.

[0136] 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 calender. 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 2.

TABLE-US-00002 TABLE 2 White opaque extrusion films Film layer Compound thickness Film 1a 100% compound 1 30 μm Film 1b 100% compound 1 100 μm Film 2 100% compound 2 30 μm Film 3 100% compound 3 30 μm Film 4a* 100% compound 4 30 μm Film 4b* 100% compound 4 100 μm Film 4c* 100% compound 4 150 μm *not according to the invention
Production of Identification Documents (ID card) Having Transparent Window:

Film 5 (Transparent Overlay Film of Card Construction):

[0137] A transparent polycarbonate film of 100 μm in thickness was produced as described hereinabove from 100% 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).

Film 6 (Core of Card Construction):

[0138] A film as per film 5 was produced but with a thickness of 540 μm.

Provision of the Window:

[0139] Stamped into each of the white opaque films 1 to 4a was a hole of 10 mm in diameter and, next to it, a second hole of 20 mm in diameter.

Provision of the Layer Construction of ID Cards

[0140] 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, one stack was formed in each case from the films in the order shown in Table 3 and lamination was carried out with the following parameters on a Bürkle lamination press.

Conditions

[0141] Preheating the press to 170-180° C.

[0142] Pressing for 8 minutes at a pressure of 15 N/cm.sup.2

[0143] Pressing for 2 minutes at a pressure of 200 N/cm.sup.2

[0144] Cooling the press to 38° C. and opening the press.

TABLE-US-00003 TABLE 3 Layer construction of the ID cards having a window Layer (1) Layer (2) Layer (3) Layer (2) Layer (1) Example 1 Film 5 Film 1a Film 6 Film 1a Film 5 (100 μm) (30 μm) (540 μm) (30 μm) (100 μm) Example 2 Film 5 Film 2  Film 6 Film 2  Film 5 (100 μm) (30 μm) (540 μm) (30 μm) (100 μm) Example 3 Film 5 Film 3  Film 6 Film 3  Film 5 (100 μm) (30 μm) (540 μm) (30 μm) (100 μm) Example 4* Film 5 Film 4a Film 6 Film 4a Film 5 (100 μm) (30 μm) (540 μm) (30 μm) (100 μm) *not according to the invention

Window Diameter of the ID Cards Before and After Lamination

[0145] The diameters of the openings in films 1 to 4a were determined before and after lamination. Before lamination the opening was measured in films 1 to 4a and after lamination the opening was measured in the laminate.

TABLE-US-00004 TABLE 4 Diameters of transparent windows before and after lamination Opening ø 10 mm Opening ø 10 mm Opening ø 20 mm Opening ø 20 mm before lamination after lamination before lamination after lamination Example 1 10.1 mm 9.90 mm 20.2 mm 19.65 mm Example 2 10.07 mm 9.88 mm 20.2 mm 19.7 mm Example 3 10.1 mm 9.80 mm 20.2 mm 19.7 mm Example 4 * 10.1 mm 9.70 mm 20.2 mm 19.40 mm * not according to the invention

[0146] All cards according to the invention comprising the white films according to the invention 1-3 (examples 1 to 3) showed a smaller change in diameter and thus better contour stability of the stamped pattern compared to example 4. This is particularly advantageous when more complex geometries are used for transparent windows.

Production of Identification Documents (ID Card) With Installed Antenna:

Film 7:

[0147] A transparent polycarbonate film of 100 μm in thickness was produced as described hereinabove from 99.9994% Makrolon™ 3108 polycarbonate and 0.0006% (6 ppm) Vulcan XC 72 from Cabot 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).

[0148] Layer constructions according to table 5 were produced. To this end, one stack was formed in each case from the films in the order shown in Table 5 and lamination was carried out with the following parameters on a Bürkle lamination press.

[0149] For the 250 μm-thick layer 4 a film 4b and a film 4c were superposed. A wire antenna was placed on film 4b in such a way that this wire antenna was in contact with layer 3.

Lamination Conditions

[0150] Preheating the press to 170-180° C.

[0151] Pressing for 8 minutes at a pressure of 15 N/cm.sup.2

[0152] Pressing for 2 minutes at a pressure of 200 N/cm.sup.2

[0153] Cooling the press to 38° C. and opening the press.

TABLE-US-00005 TABLE 5 ID documents with installed antenna between layers 3 and 4 Layer (1) Layer (2) Layer (3) Layer (4) Layer (5) Layer (6) Example 5 Film 5 Film 7 Film 1b Film 4b + 4c Film 7 Film 5 100 μm 100 μm 100 μm 250 μm 100 μm 100 μm Example 6* Film 5 Film 7 Film 4b Film 4b + 4c Film 7 Film 5 100 μm 100 μm 100 μm 250 μm 100 μm 100 μm *not according to the invention

[0154] The card in which the film according to the invention 1b adjoined the layer comprising film 4b upon which the wire antenna was placed exhibited a straight surface between the film according to the invention 1b and the wires after visual inspection (example 5). In example 6* (not according to the invention) in which the film 4b (layer 3) adjoins the layer of film 4b the antenna wires push through, i.e. there was distortion of the layers above and thus visibility of the wire antennas in the card.