POLYMER BASED COMPOSITE SUITABLE FOR BOTH LASER MARKING AND PRINTING BY DYE DIFFUSION THERMAL TRANSFER PRINTING

Abstract

A polymer based composite contains (a) a polyamide component, (b) a (co)-polyamide based on ether units and amide units, and (c) carbon black. It has been found that (1) the (co)-polyamide (b) offers sufficient absorbency for the printing ink, and (2) the selection of the polyamide component, the (co)-polyamide, and the amount of the carbon black result in both sufficient transparency and sufficient absorption centers for the laser energy. A moulded article can be made of the polymer based composite. A layered structure can be made containing at least one layer made of the polymer based composite and a security and/or valuable document containing the layered structure.

Claims

1: A polymer based composite, comprising: (a) a polyamide component (a), (b) a (co)-polyamide (b) based on an ether unit and an amide unit, and (c) carbon black.

2: The polymer based composite of claim 1, wherein the polymer based composite comprises, based on the total weight thereof, 5-95% of the polyamide component (a), and 5-95% of the (co)-polyamide (b).

3: The polymer based composite of claim 1, wherein the (co)-polyamide (b) is selected from the group consisting of poly-ether-block-amide (PEBA) (co)-polymers comprising blocks of amide units and sequences of ether units.

4: The polymer based composite of claim 1, wherein the ether units of the (co)-polyamide (b) result from at least one polyalkylene ether polyol, and wherein the (co)-polyamide (b) comprises amide units which are residues of linear aliphatic monomers and polyether sequences of a PTMG, PPG or PEG type.

5: The polymer based composite of claim 3, wherein a number-average molecular weight of the polyamide blocks is 500-12,000 g/mol, and/or a number-average molecular weight of the sequences of ether units is 200-4,000 g/mol.

6: The polymer based composite of claim 3, wherein the (co)-polyamide (b) includes amide units for which the number of carbons per amide is on average at least equal to 9, and/or the amide units of the (co)-polyamide (b) represent 50-95% by weight of the (co)-polyamide (b).

7: The polymer based composite of claim 1, wherein the polyamide component (a) is selected from the group consisting of: (a1) a linear aliphatic polyamide of the AB type having 10-12 carbon atoms, produced by polymerizing a lactam having from 10-12 carbon atoms in the monomer unit or by polycondensing a ω-aminocarboxylic acid having from 10-12 carbon atoms in the monomer unit, (a2) a linear aliphatic polyamide of the AABB type, produced by polycondensing a diamine having 6-14 carbon atoms in the monomer unit and a dicarboxylic acid having 9-14 carbon atoms in the monomer unit, (a3) a cycloaliphatic polyamide, produced by polycondensing a cycloaliphatic diamine having 10-20 carbon atoms in the monomer unit and an aliphatic dicarboxylic acid having 8-18 carbon atoms in the monomer unit, optionally further produced by a lactam having 6-14 carbon atoms or a linear aliphatic ω-aminocarboxylic acid having 6-14 carbon atoms, (a4) a semi-aromatic polyamide based on a cycloaliphatic diamine having 10-20 carbon atoms and an aromatic dicarboxylic acid having 8-18 carbon atoms, optionally further produced by a lactam having 6-14 carbon atoms or a linear aliphatic ω-aminocarboxylic acid having 6-14 carbon atoms, (a5) a semi-aromatic polyamide based on an aliphatic diamine having 2-12 carbon atoms and an aromatic dicarboxylic acid having 8-18 carbon atoms, optionally further produced by a lactam having 6-14 carbon atoms or a linear aliphatic ω-aminocarboxylic acid having 6-14 carbon atoms, and a compound or a (co)-polymer thereof.

8: The polymer based composite of claim 1, wherein the linear aliphatic polyamide (a1) or (a2) is selected from the group consisting of: PA79, PA610, PA99, PA810, PA612, PA10, PA1010, PA812, PA614, PA11, PA1012, PA1210, PA913, PA139, PA814, PA12, PA1212, PA1113, PA1014, PA1410, and a compound thereof.

9: The polymer based composite of claim 1, wherein the cycloaliphatic polyamide (a3) and the semi-aromatic polyamide (a4) are selected from the group consisting of MACM10, MACM11, MACM12, MACM13, MACM14, MACM16, PACM10, PACMI 1, PACM12, PACM13, PACM14, PACM16, TMDC10, TMDC11, TMDC12, TMDC13, TMDC14, TMDC15, TMDC16, MACMI/12, MACMT/12, PACMI/12, PACMT/12 and a mixture or a (co)-polyamide based on these systems.

10: The polymer based composite of claim 9, wherein the cycloaliphatic polyamide (a3) and the semi-aromatic polyamide (a4) are selected from the group consisting of PACM10, PACM11, PACM12, PACM13, PACM14, and PACM16, having a content of trans, trans isomer of 30-70%.

11: The polymer based composite of claim 7, wherein the cycloaliphatic polyamide (a3) is transparent with a haze of less than 3%, where both properties are determined according to ASTM D1003 on injection moulded test specimens of 2 mm in thickness.

12: The polymer based composite of claim 1, wherein the carbon black has a particle size of 10 nm-10 μm, and/or is present in an amount of 50-300 ppm, based on the total weight of the polymer based composite.

13: The polymer based composite of claim 1, wherein the composite further comprises up to 20% by weight, of one or more additional ingredients, selected from the group consisting of: stabilizers, lubricants, colorants, plasticizers, nucleants, antioxidants, impact modifiers and UV absorbers.

14: A moulded article made of the polymer based composite of claim 1.

15: A method for producing a moulding, the method comprising: moulding the polymer based composite of claim 1 to obtain a moulding which can be marked with the aid of a laser.

16: A layered structure, comprising: (A) at least one Layer (A) comprising a thermoplastic plastic, and (B) at least one Layer (B) produced from the polymer based composite of claim 1.

17: The layered structure of claim 16, wherein the thermoplastic plastic of Layer (A) is selected from cellulose acetate propionate, cellulose acetate butyrate, polyesters, polyamides, polycarbonates, polyimides, polyolefins, polyvinylchlorides, polyvinylacetals, polyethers and polysulphonamides.

18: The layered structure of claim 16, wherein Layer (A) is a white or translucent layer, and/or Layer (A) is between two Layers (B), and/or between Layer (A) and the Layer(s) (B), the layered structure has at least one further layer comprising at least one thermoplastic plastic.

19: A process for the production of the layered structure of claim 16, the process comprising: bonding films of plastic to one another by a process selected from the group consisting of lamination, coextrusion, in mould labeling, and direct gluing.

20: A security document and/or valuable document, comprising: the layered structure of claim 16.

Description

DRAWINGS

[0078] FIGS. 1-6 are the scanned images of samples of sandwich structures (EC1-EC6) after both laser engraving and D2T2 printing. Each of FIGS. 1-6 comprises two portraits of the same woman and two lines of letters. The left portraits are printed by D2T2. The right portraits and the letters are inscribed by laser engraving.

EXAMPLES

Material

[0079] TROGAMID® CX7323: PA PACM12, a polyamide produced from bis(4-aminocyclohexyl)methane and dodecanedioic acid; η.sub.rel=1.8; commercially available from Evonik Resource Efficiency GmbH;

[0080] VESTAMID® L2101F: a base-unit PA12 with η.sub.rel=2.2, commercially available from Evonik Resource Efficiency GmbH;

[0081] VESTAMID® E58-S4: a polyether-block-amide which is a (co)-polymer consisting of PA12 segments and polyether segment with η.sub.rel=1.8. (PA12 elastomer), commercially available from Evonik Resource Efficiency GmbH;

[0082] Ti-Pure™ R-105: Titanium dioxide, commercially available from the Chemours Company;

[0083] Ultranox® 626: Phosphite commercially available from Addivant Germany GmbH;

[0084] Lamp black 101: Carbon black with an average particle of 95 nm, commercially available from Orion Engineered Carbons GmbH.

Preparation of Masterbatches

[0085] Masterbatch granules having the compositions and the weight percentages as indicated in the following table 1 were prepared in a twin-screw compounding extruder (Coperion ZSK-26mc) at conventional processing temperatures for TROGAMID® CX7323 of 260-300° C. or for VESTAMID® L2101F of 250-300° C.

TABLE-US-00001 TABLE 1 Masterbatch MB1 MB2 TROGAMID ® 99.88% CX7323 VESTAMID ® 99.88% L2101F Lampblack 101  0.12%  0.12%

Preparation of the Polymer Based Composites and the Films Made Thereof

[0086] Polyamide compounds having the compositions and the weight percentages of the examples (EA1-EA2 and EB1-EB6) as indicated in the following table 2 were prepared in a twin-screw compounding extruder (Coperion ZSK-26mc) at conventional processing temperatures for TROGAMID® CX7323 of 260-300° C. or for VESTAMID® L2101F of 250-300° C.

[0087] The installation used consisted of an extruder (Dr. Collin E20M) with a screw of 20 mm diameter (D) and length of 25×D and T-die head with 25 mm slot width.

[0088] The films were prepared according to the following process:

[0089] The granules of the polyamide compounds were dried and fed into the hopper. The granules were then melted and in situ extruded out from the die. The melt of the polymer compounds came out from the die and dropped at the polishing calender. Final shaping and cooling of the films took place on the polishing calender consisting of three rolls. The films made of the polymer compounds with a thickness of 0.1 mm were obtained.

TABLE-US-00002 TABLE 2 Recipe of polyamide compounds the films made thereof EB1 EB2 EB3 EB4 EBS EBG EA1 EA2 TROGAMID ® 35%   42.5% 65%   84.8% CX7323 VESTAMID ® 35%   42.5% 68%   84.8% L2101F VESTAMID ® 50% 50% 20% 50% 50% 17% E58-S4 Masterbatch 15%   7.5% 15% of MB1 Masterbatch 15%   7.5% 15% of MB2 Ti-Pure ™ 15% 15% R-105 Ultranox ® 626   0.2%   0.2% Matrix TROGAMID ® 50% 50% 80% 100%  CX7323 VESTAMID ® 50% 50% 83% 100%  L2101F VESTAMID ® 50% 50% 20% 50% 50% 17% E58-S4 Fillers Carbon black 180 90 180 180 90 180 content (Ppm) White 15% 15% pigment content

Preparation of Samples of Sandwich Structure

[0090] Sandwich structures having two outer layers and five core layers as following were prepared: two outer layers: a film of EB1-EB6;

five core layers: a film of EA-EA2 which has the same polyamide as the outer layers.

[0091] The films of the individual layers of the sandwich structure were stacked in a mold for lamination. The mold was then transferred to a plate press machine (Collin P 300P). The films were heated to 160-200° C. for 15 min, then laminated under a pressure of 5-35 bar and cooled to 23° C. Samples of the sandwich structure had a thickness of 0.78-0.82 mm were obtained and then cut to have a dimension of 53.98 mm×85.60 mm as ID cards. The final structure of the samples is indicated in the following Table 3.

TABLE-US-00003 TABLE 3 The sandwich structures EC1 EC2 EC3 EC4 EC5 EC6 Outer layers EB1 EB2 EB3 EB4 EB5 EB6 Core layers EA1 EA2

Printing of the Samples of the Sandwich Structure by Dye Diffusion Thermal Transfer Printing (D2T2 Printing)

[0092] Printing experiments were carried out on the samples of the sandwich structure on an installation from Datacard® CD800 Card Printer with the following parameters:

[0093] Colour ribbon: Datacard 535000-003 YMCKT Colour Ribbon

[0094] Resolution: 300×600 dpi

[0095] A coloured image of a woman's portrait was printed on the left part of one outer layer of the sandwich structure. Image quality was assessed. The result is indicated in FIGS. 1-6 and Table 4.

TABLE-US-00004 TABLE 4 Performance of D2T2 printing on the examples EC1 EC2 EC3 EC4 EC5 EC6 Image +++ +++ + +++ +++ ++ quality

[0096] It can be seen that the image quality can be improved by the polyether-block-amide (e.g. VESTAMID® E58-S4) added to the plastic material.

[0097] Image quality is graded as following:

[0098] Poor (−): outline of the portrait is difficult to recognize, colours are barely transferred on the substrate from the ribbon;

[0099] Low (+): the outline of the portrait can be reorganized but without clearly defined facial features;

[0100] Medium (++): the outline of the portrait can be reorganized, facial features can be clearly observed but with some colour distortion;

[0101] High (+++): the outline of the portrait can be reorganized, facial features can be clearly observed with high colour intensity.

Laser Engraving of the Samples of the Sandwich Structure

[0102] Laser engraving was carried out on the samples of EC1-EC6 on a TruMark 3130 (TRUMPF) machine with the following parameters:

Laser medium: Nd: YVO.sub.4

Wavelength: 1064 nm

Power: 10.5 W

Voltage: 220 V

DPI: 600

Frequency: 45000 Hz

[0103] In the laser engraving, a black-and-white portrait of a woman and letters were inscribed the right part and bottom part respectively in one outer layer of the individual samples of EC1-EC6. As also indicated in FIGS. 1-6, an excellent contrast and very good graduation of the greyscales were achieved in EC1-EC6.