IMPROVED METHOD FOR PARTIAL COLORING OF PLASTIC PARTS

Description

[0001] The present invention relates to an improved method for partially coloring, in particular for colored laser engraving, plastic parts, in particular thermoplastic parts, very particularly thermoplastic parts comprising a layer structure, a security document comprising a partially colored plastic part and a device for partially coloring plastic parts.

[0002] The ability to laser engrave plastic parts in color is of interest to the entire plastic parts manufacturing industry. Of interest here is the color laser engraving of three-dimensionally shaped plastic parts, for example, for the automotive industry. This allows switches, panels, etc. to be engraved with colored symbols. Plastic parts that have a coating for surface protection can also be laser engraved in color. The laser beam removes the coating and at the same time the dye migrates into the plastic surface at that point. Unprotected plastic surfaces can also be laser engraved in color and then painted to ensure the plastic parts have a consistent glossy appearance and offer protection against scratches and chemical damage.Until now, such colored symbols could be produced, for example, in a first production step using plastic injection molding with several colored components. In a second production step, the plastic parts must be coated with an opaque color. In a third production step, the colored layer must be laser engraved to expose the underlying plastic surface. Optionally, a protective coating can be applied in a fourth production step.

[0003] Alternatively, transparent plastic films can be engraved in color on the back and then back-injected with a thermoplastic, according to the film insert molding process, to obtain glossy or uniform-looking surfaces. This process is disclosed, for example, in EP-A 0691201, Example 1.

[0004] In the market for security and / or valuable documents, especially identification documents (ID documents), there is a need for color personalization of these documents using lasers. Personalizing ID documents that consist partially or entirely of polymer films using laser engraving is state of the art. However, the laser engraving processes currently available in ID documents only create images and text in various shades of gray. Colored elements cannot be created using laser engraving. Only in combination with previously applied color layers, which are subsequently modified using a laser, is it possible to generate color images in or on plastic parts or ID documents.

[0005] In recent years, processes have been developed, particularly in the field of security and / or valuable documents, especially ID documents, that allow the creation of colored elements in these documents, which are constructed entirely or partially from polymer films. These processes are described, for example, in WO-A 03 / 056507, EP-A 2752302, or JP-A 2012-011688, but involve considerable technical effort. All processes involve a printing process to implement the coloring.

[0006] WO-A 2017 / 167651 discloses a method for the partial coloring, in particular for colored laser engraving, of plastic parts, in particular thermoplastic parts, especially plastic films.

[0007] The unpublished patent application LU-A100327 discloses an improved process for the partial coloring, in particular for colored laser engraving, of plastic parts, especially thermoplastic parts, and especially plastic films. In the process according to LU-A100327, the plastic parts comprise additives that exhibit an absorption maximum in the wavelength range of the focused non-ionizing electromagnetic radiation used, or the plastic part is coated with an additive in the form of a coating agent.

[0008] However, the disadvantage of both processes is the intensity, sharpness and positional accuracy of the resulting partial coloring, especially the resulting colored laser engraving.

[0009] Therefore, the object of the present invention was to provide an improved method for partial coloring, in particular for colored laser engraving, of plastic parts, preferably thermoplastic parts, very particularly thermoplastic parts comprising a layer structure, such as plastic films and / or film layer composites, so that a positionally accurate, sharp and uniformly intensive partial coloring, in particular colored laser engraving, results.

[0010] This problem was surprisingly solved by the method defined in claim 1.

[0011] In the context of this invention, "essentially" is understood to mean that a colored element is created only at the areas irradiated in step ii), which is clearly recognizable to the eye as a visible colored element.

[0012] Immersion in step i) refers to at least partially wetting the surface of the plastic part (A) with the dye bath (B) containing at least one colorant. Immersion in step i) can also be achieved by otherwise wetting the surface of the plastic part (A) using a dye layer b).

[0013] In the context of this invention, constant temperature of the dyeing bath (B) is understood to mean that the temperature of the dyeing bath can deviate from the selected temperature of the dyeing bath (B) by a maximum of 10 °C upwards or downwards, preferably by a maximum of 8 °C upwards or downwards, particularly preferably by a maximum of 5 °C upwards or downwards, during the duration of the process.

[0014] Alternatively, the dyeing bath (B) may experience a variation in temperature of more than 10 °C, preferably up to 20 °C, further preferably up to 50 °C, particularly preferably up to 100 °C, during the duration of the process.

[0015] The method according to the invention is characterized in that the partial coloring of the plastic part, in particular the thermoplastic part, very particularly the thermoplastic part comprising a layer structure, takes place essentially at the areas irradiated in step ii) with improved intensity and improved sharpness of the coloring. The remaining plastic part (A) has no or only very weak coloring in the non-irradiated areas. Thus, it is possible to color specific areas of the plastic part in order to apply, for example, an image, personalization, logo, symbol, or lettering to this plastic part using the method according to the invention. These cannot be easily removed from the plastic surface. Thus, the method according to the invention is particularly suitable for the production of security and identification documents.

[0016] Particularly when irradiated with laser radiation, these colored elements achieve particularly high resolutions of 5000 dpi and possibly even higher. The process according to the invention requires neither a high-precision printing technology nor the use of different laser strengths, for example, lasers emitting at different wavelengths, provided the irradiation in step ii) is carried out with laser radiation. Furthermore, the process according to the invention, as described further below, is suitable for applying colored elements both to two- and / or three-dimensional plastic parts (A) and to thermoplastic parts (A) comprising a layer structure containing one or more layers of a thermoplastic.

[0017] Highly focused laser systems can produce continuous colored lines, a feature of security printing, with a width of 10 µm. This is not possible with any of the printing processes available today.

[0018] The plate (D) can be placed in the dye bath (B) in such a way that a constant distance between the surface of the plastic part (A) and the plate (D) results throughout the entire process. This distance between the surface of the plastic part (A) and the plate (D) is also referred to as the immersion depth. Within the immersion depth range, the focused non-ionizing electromagnetic radiation (C) penetrates the dye bath (B) before reaching the surface of (A).

[0019] Thus, the immersion depth can be precisely adjusted throughout the entire process and can thus also be kept constant throughout the entire process to achieve partial coloring of high intensity and sharpness. In one embodiment, the immersion depth can be ≤ 120 mm, preferably ≥ 0.01 to ≤ 100 mm, particularly preferably ≥ 0.1 to ≤ 20 mm, and most preferably ≥ 0.1 to ≤ 5.0 mm.

[0020] For two-dimensionally shaped plastic parts (A), in particular thermoplastic parts comprising a layered structure containing one or more layers of a thermoplastic, a preferably flat plate (D) can be used. Preferably, the plate (D) is arranged parallel to the surface of (A). In another embodiment for the laser engraving of two-dimensionally shaped plastic parts (A), a plate (D) of the size of the partial coloring of the plastic part to be achieved can be used in the process according to the invention.

[0021] For three-dimensional molded plastic parts (A), a correspondingly three-dimensionally shaped plate (D) can be used to achieve a consistent immersion depth. Preferably, a plate (D) is used that is the size of the desired partial coloring in the plastic part (A). This can reduce the shape complexity of the plate (D). Preferably, the plate (D) is arranged parallel to the tangent of the three-dimensional shape (A) that is to be described in color.

[0022] In a preferred embodiment of the method according to the invention, (C) is irradiated perpendicular to the plate (D).

[0023] In the process according to the invention, the focused non-ionizing electromagnetic beam (C), preferably a laser beam, passes through the plate (D) comprising one or more radiation-outcoupling materials. To minimize the loss of intensity of (C) and also the scattering of (C) on the plate (D), the radiation-outcoupling material of the plate (D) is preferably selected from materials with a high surface quality and radiation permeability.Radiation-outcoupling materials of the plate (D) can have a scratch-dig value, determined according to ISO 10110-8, of ≥ 80-50 to ≤ 10-10, preferably of ≥ 60-40 to ≤ 20-10, a surface roughness Rq, determined according to ISO 10110-8, of ≥ 0.5 to ≤ 500 nm, preferably of ≥ 0.7 to ≤ 100 nm, particularly preferably of ≥ 1 nm to ≤ 10 nm, and a radiation transmittance for the selected radiation, determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025, of ≥ 50% to ≤ 99.95%, preferably of ≥ 60% to ≤ 99.9%, particularly preferably of ≥ 70% to ≤ 99.89%.

[0024] In one embodiment, one or more radiation-outcoupling materials of the plate (D) can comprise at least one or more compounds from the group of glass, such as non-oxide glasses, in particular halide glasses or chalcogenide glasses, oxide glasses, in particular phosphate-containing glasses, silicate-containing glasses, borate glasses, aluminosilicate glasses, lead silicate glasses, alkali silicate glasses, borosilicate glasses, alkali borate glasses, alkali-alkaline earth silicate glass, quartz glass, organic glasses, radiation-permeable plastic, mineral glass, synthetic glass, radiation-permeable ceramic material (e.g. Perlucor™< from CeramTec GmbH or fine-crystalline spinel ceramics from the Fraunhofer Institute for Ceramic Technologies and Systems IKTS, or radiation-permeable glass ceramic Robax™< from Schott AG) and / or mixtures of at least two of the above compounds.Preferably glass, radiolucent plastic and / or synthetic glass.

[0025] The dyeing bath (B) has a temperature of ≤ 99°C to ≥ -60°C, preferably from ≤ 99°C to ≥ 0°C, preferably from ≤ 70°C to ≥ 10°C, most preferably from ≤ 50°C to ≥ 15°C, and maintains a constant temperature throughout the process. In a preferred embodiment of the invention, the temperature of the dyeing bath (B) between the surface of the plastic part (A) and the plate (D) maintains a constant temperature throughout the process.

[0026] Alternatively, the temperature of the dyeing bath (B) can be varied during the duration of the process in a temperature range from 0 °C to 100 °C, preferably from 5 °C to 80 °C, further preferably from 10 °C to 60 °C, more preferably from 15 °C to 40 °C, particularly preferably from 20 °C to 30 °C.

[0027] In a further embodiment, the temperature of the dyeing bath (B), in particular the temperature of the dyeing bath (B) between the surface of the plastic part (A) and the plate (D), can be kept constant by appropriate temperature control devices, in particular cooling devices.

[0028] In another embodiment, the dye bath (B) can be continuously passed through the gap between the surface of the plastic part (A) and the plate (D) so that no heat build-up occurs between the surface of (A) and (D) and so the temperature between the surface of (A) and (D) is kept constant in the selected temperature range.

[0029] In the process according to the invention, a variety of plastic parts (A), in particular thermoplastic parts, very particularly thermoplastic parts comprising a layered structure, can be used. The preferably thermoplastic parts, very particularly thermoplastic parts comprising a layered structure, can particularly preferably be a thermoplastic selected from polymers of ethylenically unsaturated monomers and / or polycondensates of bifunctional reactive compounds and / or polyaddition products of bifunctional reactive compounds. For certain applications, such as in the field of identification documents, it may be advantageous and therefore preferred to use a transparent thermoplastic, preferably in the form of plastic films.

[0030] Particularly suitable thermoplastics are one or more polycarbonates or copolycarbonates based on diphenols, poly- or copolyacrylate(s) and poly- or copolymethacrylate(s) such as, for example and preferably, polymethyl methacrylate or poly(meth)acrylate (PMMA), poly- or copolymer(s) with styrene such as, for example and preferably, polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), or polystyrene-acrylonitrile (SAN), thermoplastic polyurethane(s), and polyolefin(s), such as, for example and preferably, polypropylene types or polyolefins based on cyclic olefins (e.g.TOPAS ®< , Hoechst), poly- or copolycondensate(s) of terephthalic acid, such as, by way of example and with preference, 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) ), polyamide (PA), poly- or copolycondensate(s) of naphthalenedicarboxylic acid, such as, by way of example and with preference, polyethylene glycol naphthalate (PEN), poly- or copolycondensate(s) of at least one cycloalkyldicarboxylic acid, such as, by way of example and with preference, polycyclohexanedimethanolcyclohexanedicarboxylic acid (PCCD), polysulfones (PSU), mixtures of at least two of the aforementioned or blends thereof.

[0031] Particularly preferred thermoplastics are one or more polycarbonates or copolycarbonates based on diphenols or blends containing at least one polycarbonate or copolycarbonate. Very particular preference is given to blends comprising at least one polycarbonate or copolycarbonate and at least one poly- or copolycondensate of terephthalic acid, of naphthalenedicarboxylic acid or of a cycloalkyldicarboxylic acid, preferably of cyclohexanedicarboxylic acid. Very particular preference is given to polycarbonates or copolycarbonates, in particular having average molecular weights Mw of 500 to 100,000, preferably of 10,000 to 80,000, particularly preferably of 15,000 to 40,000, or blends thereof with at least one poly- or copolycondensate of terephthalic acid having average molecular weights Mw of 10,000 to 200,000, preferably of 21,000 to 120,000.

[0032] In preferred embodiments of the invention, polyalkylene terephthalates are suitable as poly- or copolycondensates of terephthalic acid. Suitable polyalkylene terephthalates include, for example, reaction products of aromatic dicarboxylic acids or their reactive derivatives (e.g., dimethyl esters or anhydrides) and aliphatic, cycloaliphatic, or araliphatic diols, and mixtures of these reaction products.

[0033] Preferred polyalkylene terephthalates can be prepared from terephthalic acid (or its reactive derivatives) and aliphatic or cycloaliphatic diols with 2 to 10 C atoms by known methods (Kunststoff-Handbuch, Vol. VIII, p. 695 ff, Karl-Hanser-Verlag, Munich 1973).

[0034] Preferred polyalkylene terephthalates contain at least 80 mol%, preferably 90 mol% of terephthalic acid residues, based on the dicarboxylic acid component, and at least 80 mol%, preferably at least 90 mol% of ethylene glycol and / or 1,4-butanediol and / or 1,4-cyclohexanedimethanol residues, based on the diol component.

[0035] The preferred polyalkylene terephthalates may contain, in addition to terephthalic acid residues, up to 20 mol% of residues of other aromatic dicarboxylic acids having 8 to 14 C atoms or aliphatic dicarboxylic acids having 4 to 12 C atoms, such as, for example, residues of phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, 4,4'-diphenyldicarboxylic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, cyclohexanediacetic acid.

[0036] The preferred polyalkylene terephthalates can contain, in addition to ethylene or butanediol-1,4-glycol residues, up to 80 mol% of other aliphatic diols having 3 to 12 C atoms or cycloaliphatic diols having 6 to 21 C atoms, e.g. B. residues of propanediol-1,3, 2-ethylpropanediol-1,3, neopentyl glycol, pentane-diol-1,5, hexanediol-1,6, cyclohexanedimethanol-1,4, 3-methylpentanediol-2,4, 2-methylpentanediol-2,4, 2,2,4-trimethylpentanediol-1,3 and 2-Ethylhexanediol-1,6, 2,2-Diethylpropanediol-1,3, Hexanediol-2,5, 1,4-Di-([beta]-hydroxyethoxy)-benzene, 2,2-Bis-(4-hydroxycyclohexyl)-propane, 2,4-Dihydroxy-1,1,3,3-tetramethylcyclobutane, 2,2-Bis-(3-[beta]-hydroxyethoxyphenyl)-propane and 2,2-Bis-(4-hydroxypropoxyphenyl)-propane (see DE-OS 24 07 674, 24 07 776, 27 15 932).

[0037] The polyalkylene terephthalates can be branched by incorporating relatively small amounts of tri- or tetrahydric alcohols or tri- or tetrabasic carboxylic acids, as described, for example, in German Offenlegungsschrift 19 00 270 and US Pat. No. 3,692,744. Examples of preferred branching agents are trimesic acid, trimellitic acid, trimethylolethane and propane, and pentaerythritol.

[0038] Preferably, not more than 1 mol% of the branching agent is used, based on the acid component.

[0039] Particularly preferred are polyalkylene terephthalates which have been prepared solely from terephthalic acid and its reactive derivatives (e.g. its dialkyl esters) and ethylene glycol and / or 1,4-butanediol and / or 1,4-cyclohexanedimethanol residues, and mixtures of these polyalkylene terephthalates.

[0040] Preferred polyalkylene terephthalates are also copolyesters made from at least two of the above-mentioned acid components and / or from at least two of the above-mentioned alcohol components; particularly preferred copolyesters are poly(ethylene glycol / butanediol-1,4) terephthalates.

[0041] The polyalkylene terephthalates preferably used as components preferably have an intrinsic viscosity of approximately 0.4 to 1.5 dl / g, preferably 0.5 to 1.3 dl / g, each measured in phenol / o-dichlorobenzene (1:1 parts by weight) at 25°C.

[0042] In particularly preferred embodiments of the invention, the blend of at least one polycarbonate or copolycarbonate with at least one poly- or copolycondensate of terephthalic acid is a blend of at least one polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate. Such a blend of polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate can preferably be one with 1 to 90 wt.% polycarbonate or copolycarbonate and 99 to 10 wt.% poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate, preferably with 1 to 90 wt.% polycarbonate and 99 to 10 wt.% polybutylene terephthalate or glycol-modified polycyclohexanedimethylene terephthalate, wherein the proportions are 100 wt.-%. Particularly preferably, such a blend of polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexane dimethylene terephthalate can be one with 20 to 85 wt.% polycarbonate or copolycarbonate and 80 to 15 wt.% poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexane dimethylene terephthalate, preferably with 20 to 85 wt.% polycarbonate and 80 to 15 wt.% polybutylene terephthalate or glycol-modified polycyclohexane dimethylene terephthalate, where the proportions add up to 100 wt.%. Most preferably, such a blend of polycarbonate or copolycarbonate with poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate can be one with 35 to 80 wt.% polycarbonate or copolycarbonate and 65 to 20 wt.-% poly- or copolybutylene terephthalate or glycol-modified poly- or copolycyclohexanedimethylene terephthalate, preferably with 35 to 80 wt.% polycarbonate and 65 to 20 wt.% polybutylene terephthalate or glycol-modified polycyclohexanedimethylene terephthalate, the proportions adding up to 100 wt.%. In particularly preferred embodiments, the above-mentioned compositions can be blends of polycarbonate and glycol-modified polycyclohexanedimethylene terephthalate.

[0043] In preferred embodiments, aromatic polycarbonates or copolycarbonates are particularly suitable as polycarbonates or copolycarbonates.

[0044] The polycarbonates or copolycarbonates can be linear or branched in a known manner.

[0045] These polycarbonates can be produced in a known manner from diphenols, carbonic acid derivatives, optionally chain terminators, and optionally branching agents. Details of the production of polycarbonates have been documented in numerous patents dating back about 40 years. As examples, reference is made here to Schnell, "Chemistry and Physics of Polycarbonates", Polymer Reviews, Volume 9, Interscience Publishers, New York, London, Sydney 1964, to D. Freitag, U. Grigo, PR Müller, H. Nouvertne', BAYER AG, "Polycarbonates" in Encyclopedia of Polymer Science and Engineering, Volume 11, Second Edition, 1988, pages 648-718 and finally to Drs. U. Grigo, K. Kirchner and PR Müller "Polycarbonate" in Becker / Braun, Kunststoff-Handbuch, Volume 3 / 1, Polycarbonates, Polyacetals, Polyesters, Celluloseesters, Carl Hanser Verlag Munich, Vienna 1992, pages 117-299.

[0046] Suitable diphenols can be, for example, dihydroxyaryl compounds of the general formula (I), HO-Z-OH (I) wherein Z is an aromatic radical having 6 to 34 C atoms, which may contain one or more optionally substituted aromatic nuclei and aliphatic or cycloaliphatic radicals or alkylaryls or heteroatoms as bridge members.

[0047] Examples of suitable dihydroxyaryl compounds are: dihydroxybenzenes, dihydroxydiphenyls, bis-(hydroxyphenyl)-alkanes, bis-(hydroxyphenyl)-cycloalkanes, bis-(hydroxyphenyl)-aryls, bis-(hydroxyphenyl)-ethers, bis-(hydroxyphenyl)-ketones, bis-(hydroxyphenyl)-sulfides, bis-(hydroxyphenyl)-sulfones, bis-(hydroxyphenyl)-sulfoxides, 1,1'-bis-(hydroxyphenyl)-diisopropylbenzenes, and their nuclear alkylated and nuclear halogenated compounds.

[0048] These and other suitable dihydroxyaryl compounds are described, for example, in DE-A 3 832 396, FR-A 1 561 518, in H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York 1964, p. 28 ff.; p. 102 ff. and in DG Legrand, JT Bendler, Handbook of Polycarbonate Science and Technology, Marcel Dekker, New York 2000, p. 72 ff.

[0049] Bevorzugte Dihydroxyarylverbindungen sind beispielsweise Resorcin, 4,4'-Dihydroxydiphenyl, Bis-(4-hydroxyphenyl)-methan, Bis-(3,5-dimethyl-4-hydroxyphenyl)-methan, Bis-(4-hydroxyphenyl)-diphenyl-methan, 1,1-Bis-(4-hydroxyphenyl)-1-phenyl-ethan, 1,1-Bis-(4-hydroxyphenyl)-1-(1-naphthyl)-ethan, 1,1-Bis-(4-hydroxyphenyl)-1-(2-naphthyl)-ethan, 2,2-Bis-(4-hydroxyphenyl)-propan, 2,2-Bis-(3-methyl-4-hydroxyphenyl)-propan, 2,2-Bis-(3,5-dimethyl-4-hydroxyphenyl)-propan, 2,2-Bis-(4-hydroxyphenyl)-1-phenyl-propan, 2,2-Bis-(4-hydroxyphenyl)-hexafluor-propan, 2,4-Bis-(4-hydroxyphenyl)-2-methyl-butan, 2,4-Bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutan, 1,1-Bis-(4-hydroxyphenyl)-cyclohexan, 1,1-Bis-(3,5-dimethyl-4-hydroxyphenyl)-cylohexan, 1,1-Bis-(4-hydroxyphenyl)-4-methyl-cylohexan, 1,3-Bis-[2-(4-hydroxyphenyl)-2-propyl]-benzol, 1,1'- Bis-(4-hydroxyphenyl)-3-diisopropyl-benzol, 1,1'-Bis-(4-hydroxyphenyl)-4-diisopropyl-benzol, 1,3-Bis-[2-(3,5-dimethyl-4-hydroxyphenyl)-2-propyl]-benzol,Bis-(4-hydroxyphenyl) ether, bis-(4-hydroxyphenyl) sulfide, bis-(4-hydroxyphenyl) sulfone, bis-(3,5-dimethyl-4-hydroxyphenyl) sulfone and 2,2',3,3'-tetrahydro-3,3,3',3'-tetramethyl-1,1'-spirobi-[1H-indene]-5,5'-diol or dihydroxydiphenylcycloalkanes of the formula (Ia), wherein R 1< and R 2< are independently of one another hydrogen, halogen, preferably chlorine or bromine, C 1 -C 8 alkyl, C 5 -C 6 cycloalkyl, C 6 -C 10 aryl, preferably phenyl, and C 7 -C 12 aralkyl, preferably phenyl-C 1 -C 4 alkyl, in particular benzyl, m is an integer from 4 to 7, preferably 4 or 5, R 3< and R 4< can be selected individually for each X, independently of one another hydrogen or C 1 -C 6 alkyl and X is carbon, with the proviso that on at least one atom X, R 3< and R 4< are simultaneously alkyl. In the formula (Ia), one or two atom(s) X, in particular only on one atom X 3< and R 4< are simultaneously alkyl.

[0050] The preferred alkyl radical for the radicals R 3 and R 4 in formula (Ia) is methyl. The X atoms in the alpha position to the diphenyl-substituted C atom (C-1) are preferably not dialkyl-substituted; however, alkyl disubstitution in the beta position to C-1 is preferred.

[0051] Particularly preferred dihydroxydiphenylcycloalkanes of the formula (Ia) are those having 5 and 6 ring C atoms X in the cycloaliphatic radical (m = 4 or 5 in formula (Ia)), for example the diphenols of the formulas (Ia-1) to (Ia-3),

[0052] A particularly preferred dihydroxydiphenylcycloalkane of formula (Ia) is 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane (formula (Ia-1) with R 1< and R 2< equal to H).

[0053] Such polycarbonates can be prepared from dihydroxydiphenylcycloalkanes of formula (Ia) according to EP-A 359 953.

[0054] Particularly preferred dihydroxyaryl compounds are resorcinol, 4,4'-dihydroxydiphenyl, bis-(4-hydroxyphenyl)-diphenyl-methane, 1,1-bis-(4-hydroxyphenyl)-1-phenyl-ethane, bis-(4-hydroxyphenyl)-1-(1-naphthyl)-ethane, bis-(4-hydroxyphenyl)-1-(2-naphthyl)-ethane, 2,2-bis-(4-hydroxyphenyl)-propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)-propane, 1,1-bis-(4-hydroxyphenyl)-cyclohexane, 1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane, 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane, 1,1'-bis-(4-hydroxyphenyl)-3-diisopropylbenzene and 1,1'-bis-(4-hydroxyphenyl)-4-diisopropylbenzene.

[0055] Particularly preferred dihydroxyaryl compounds are 4,4'-dihydroxydiphenyl and 2,2-bis-(4-hydroxyphenyl)-propane.

[0056] Both a single dihydroxyaryl compound can be used to form homopolycarbonates and various dihydroxyaryl compounds can be used to form copolycarbonates. Both a single dihydroxyaryl compound of formula (I) or (Ia) can be used to form homopolycarbonates, and several dihydroxyaryl compounds of formula (I) and / or (Ia) can be used to form copolycarbonates. The various dihydroxyaryl compounds can be linked to one another either randomly or blockwise.In the case of copolycarbonates of dihydroxyaryl compounds of formula (I) and (Ia), the molar ratio of dihydroxyaryl compounds of formula (Ia) to the other dihydroxyaryl compounds of formula (I) optionally to be used is preferably between 99 mol% (Ia) to 1 mol% (I) and 2 mol% (Ia) to 98 mol% (I), preferably between 99 mol% (Ia) to 1 mol% (I) and 10 mol% (Ia) to 90 mol% (I) and in particular between 99 mol% (Ia) to 1 mol% (I) and 30 mol% (Ia) to 70 mol% (I).

[0057] A particularly preferred copolycarbonate can be prepared using 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane and 2,2-bis-(4-hydroxyphenyl)-propane dihydroxyaryl compounds of formula (Ia) and (I).

[0058] Suitable carbonic acid derivatives can be, for example, diaryl carbonates of the general formula (II), wherein R, R' and R" independently of one another are identical or different and represent hydrogen, linear or branched C 1 -C 34 alkyl, C 7 -C 34 alkylaryl or C 6 -C 34 aryl, R can also represent -COO-R‴, where R‴ represents hydrogen, linear or branched C 1 -C 34 alkyl, C 7 -C 34 alkylaryl or C 6 -C 34 aryl.

[0059] Bevorzugte Diarylcarbonate sind beispielsweise Diphenylcarbonat, Methylphenyl-phenylcarbonate und Di-(methylphenyl)-carbonate, 4-Ethylphenyl-phenyl-carbonat, Di-(4-ethylphenyl)-carbonat, 4-n-Propylphenyl-phenyl-carbonat, Di-(4-n-propylphenyl)-carbonat, 4-iso-Propylphenyl-phenyl-carbonat, Di-(4-iso-propylphenyl)-carbonat, 4-n-Butylphenyl-phenyl-carbonat, Di-(4-n-butylphenyl)-carbonat, 4-iso-Butylphenyl-phenyl-carbonat, Di-(4-iso-butylphenyl)-carbonat, 4-tert-Butylphenyl-phenyl-carbonat, Di-(4-tert-butylphenyl)-carbonat, 4-n-Pentylphenyl-phenyl-carbonat, Di-(4-n-pentylphenyl)-carbonat, 4-n-Hexylphenyl-phenyl-carbonat, Di-(4-n-hexylphenyl)-carbonat, 4-iso-Octylphenyl-phenyl-carbonat, Di-(4-iso-octylphenyl)-carbonat, 4-n-Nonylphenyl-phenyl-carbonat, Di-(4-n-nonylphenyl)-carbonat, 4-Cyclohexylphenyl-phenyl-carbonat, Di-(4-cyclohexylphenyl)-carbonat, 4-(1-Methyl-1-phenylethyl)-phenyl-phenyl-carbonat, Di-[4-(1-methyl-1-phenylethyl)-phenyl]-carbonat, Biphenyl-4-yl-phenyl-carbonat,Di-(biphenyl-4-yl)-carbonat, 4-(1-Naphthyl)-phenyl-phenyl-carbonat, 4-(2-Naphthyl)-phenyl-phenyl-carbonat, Di-[4-(1-naphthyl)-phenyl]-carbonat, Di-[4-(2-naphthyl)phenyl]-carbonat, 4-Phenoxyphenyl-phenyl-carbonat, Di-(4-phenoxyphenyl)-carbonat, 3-Pentadecylphenyl-phenyl-carbonat, Di-(3-pentadecylphenyl)-carbonat, 4-Tritylphenyl-phenyl-carbonat, Di-(4-tritylphenyl)-carbonat, Methylsalicylat-phenyl-carbonat, Di-(methylsalicylat)-carbonat, Ethylsalicylat-phenyl-carbonat, Di-(ethylsalicylat)-carbonat, n-Propylsalicylat-phenyl-carbonat, Di-(n-propylsalicylat)-carbonat, iso-Propylsalicylat-phenyl-carbonat, Di-(iso-propylsalicylat)-carbonat, n-Butylsalicylat-phenyl-carbonat, Di-(n-butylsalicylat)-carbonat, iso-Butylsalicylat-phenyl-carbonat, Di-(iso-butylsalicylat)-carbonat, tert-Butylsalicylat-phenyl-carbonat, Di-(tert-butylsalicylat)-carbonat, Di-(phenylsalicylat)-carbonat und Di-(benzylsalicylat)-carbonat.,

[0060] Particularly preferred diaryl compounds are diphenyl carbonate, 4-tert-butylphenyl phenyl carbonate, di-(4-tert-butylphenyl) carbonate, biphenyl 4-yl phenyl carbonate, di-(biphenyl 4-yl) carbonate, 4-(1-methyl-1-phenylethyl) phenyl phenyl carbonate, di-[4-(1-methyl-1-phenylethyl) phenyl] carbonate, and di-(methyl salicylate) carbonate. Diphenyl carbonate is most preferred.

[0061] Either one diaryl carbonate or different diaryl carbonates can be used.

[0062] To control or modify the end groups, one or more monohydroxyaryl compounds can be used as chain terminators, for example, which were not used in the preparation of the diaryl carbonate(s). These can be those of the general formula (III), where RA< represents linear or branched C 1 -C 34 alkyl, C 7 -C 34 alkylaryl, C 6 -C 34 aryl or - COO-RD<, where RD< represents hydrogen, linear or branched C 1 -C 34 alkyl, C 7 -C 34 alkylaryl or C 6 -C 34 aryl, and RB< , RC< independently of one another, identical or different, represent hydrogen, linear or branched C 1 -C 34 alkyl, C 7 -C 34 alkylaryl or C 6 -C 34 aryl.

[0063] Such monohydroxyaryl compounds are, for example, 1-, 2- or 3-methylphenol, 2,4-dimethylphenol, 4-ethylphenol, 4-n-propylphenol, 4-iso-propylphenol, 4-n-butylphenol, 4-isobutylphenol, 4-tert-butylphenol, 4-n-pentylphenol, 4-n-hexylphenol, 4-iso-octylphenol, 4-n-nonylphenol, 3-pentadecylphenol, 4-cyclohexylphenol, 4-(1-methyl-1-phenylethyl)phenol, 4-phenylphenol, 4-phenoxyphenol, 4-(1-naphthyl)phenol, 4-(2-naphthyl)phenol, 4-tritylphenol, methyl salicylate, Ethyl salicylate, n-propyl salicylate, Isopropyl salicylate, n-butyl salicylate, isobutyl salicylate, tert-butyl salicylate, phenyl salicylate, and benzyl salicylate. Preferred are 4-tert-butylphenol, 4-isooctylphenol, and 3-pentadecylphenol.

[0064] Suitable branching agents can be compounds with three or more functional groups, preferably those with three or more hydroxyl groups.

[0065] Suitable compounds with three or more phenolic hydroxyl groups are, for example, phloroglucinol, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptene-2, 4,6-dimethyl-2,4,6-tri-(4-hydroxyphenyl)-heptane, 1,3,5-tri-(4-hydroxyphenyl)-benzene, 1,1,1-tri-(4-hydroxyphenyl)-ethane, tri-(4-hydroxyphenyl)-phenylmethane, 2,2-bis-(4,4-bis-(4-hydroxyphenyl)-cyclohexyl]-propane, 2,4-bis-(4-hydroxyphenyl-isopropyl)-phenol and tetra-(4-hydroxyphenyl)-methane.

[0066] Other suitable compounds with three or more functional groups are, for example, 2,4-dihydroxybenzoic acid, trimesic acid trichloride, cyanuric acid trichloride and 3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole.

[0067] Preferred branching agents are 3,3-bis-(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole and 1,1,1-tri-(4-hydroxyphenyl)ethane.

[0068] The plastic part containing the aforementioned thermoplastic polymers can be extruded, co-extruded, cast, three-dimensionally printed and / or injection-molded. The plastic part can also be a three-dimensional plastic part. Furthermore, it is possible for the plastic part to also be a plastic part comprising a layer structure such as films, film layer composites and / or sheets, as well as combinations thereof, e.g. back-injected films containing the aforementioned polymers. The plastic part is particularly preferably a film, film layer composite and / or a sheet containing the aforementioned polymers, which are produced by extrusion and / or coextrusion.

[0069] In one embodiment, the plastic part (A), in particular a thermoplastic plastic part, very particularly a thermoplastic plastic part comprising a layer structure, comprises at least one additive which has an absorption maximum in the wavelength range of the focused non-ionizing electromagnetic radiation used, or (A) is coated with at least one additive in the form of a coating agent which has an absorption maximum in the wavelength range of the focused non-ionizing electromagnetic radiation used.

[0070] In principle, all laser-sensitive additives, so-called laser marking additives, are suitable as additives, i.e., those containing an absorber in the wavelength range of the radiation to be used (C). The additive preferably comprises at least one or more organic and / or inorganic IR absorbers, preferably inorganic IR absorbers. Such additives and their use in molding compounds are described, for example, in WO-A 2004 / 50766 and WO-A 2004 / 50767 and are offered commercially by DSM under the brand name Micabs™.

[0071] Suitable organic IR absorbers include compounds that exhibit the highest possible absorption between 700 and 2500 nm (near infrared = NIR). Suitable examples include known infrared absorbers, such as those described by substance class in M. Matsuoka, Infrared Absorbing Dyes, Plenum Press, New York, 1990. Particularly suitable are infrared absorbers from the substance classes of azo, azomethine, methine, anthraquinone, indanthrone, pyranthrone, flavanthrone, benzanthrone, phthalocyanine, perylene, dioxazine, thioindigo, isoindoline, isoindolinone, quinacridone, pyrrolopyrrole, or quinophthalone pigments, as well as metal complexes of azo, azomethine, or methine dyes or metal salts of azo compounds. Phthalocyanines and naphthalocyanines are particularly suitable. Due to their improved solubility in thermoplastics, phthalocyanines and naphthalocyanines with bulky side groups are preferable.

[0072] Suitable inorganic IR absorbers are, for example, mixed oxides of metals such as phosphorus-containing tin-copper mixed oxides, as described, for example, in WO-A 2006 / 042714, those from the group of borides and / or tungstates and mixtures thereof, preferably at least one or more IR absorbers from the group of borides and / or tungstates and mixtures thereof, particularly preferably at least one or more IR absorbers from the group of tungstates.

[0073] Examples of inorganic IR absorbers from the boride group are compounds of the type M x B y (M = La, Ce, Pr, Nd, Tb, Dy, Ho, Y, Sm, Eu, ER, Tm, Yb, Lu, Sr, Ti, Zr, Hf, V, Ta, Cr, Mo, W and Ca; and x and y are an integer from 1 to 6) where lanthanum hexaboride (LaB 6 ), praseodymium boride (PrB 6 ), neodymium boride (NdB 6 ), cerium boride (CeB 6 ), terbium boride (TbB 6 ), dysprosium boride (DyB 6 ), holmium boride (HoB 6 ), yttrium boride (YB 6 ), samarium boride (SmB 6 ), europium boride (EuB 6 ), erbium boride (ErB 6 ), Thulium boride (TmB 6 ), ytterbium boride (YbB 6 ), lutetium boride (LuB 6 ), strontium boride (SrB 6 ), calcium boride (CaB 6 ), titanium boride (TiB 2 ), zirconium boride (ZrB 2 ), hafnium boride (HfB 2 ), vanadium boride (VB 2 ), tantalum boride (TaB 2 ), chromium boride (CrB and CrB 2 ), molybdenum boride (MoB 2 , Mo 2 B 5 and MoB), tungsten boride (W 2 B 5 ), or combinations of these borides are suitable.

[0074] Examples of inorganic IR absorbers from the group of tungstates are those from the group of tungsten compounds of the type W y O z (W = tungsten, O = oxygen; z / y = 2.20 - 2.99) and / or M x W y O z (M = H, He, alkali metal, alkaline earth metal, metal from the group of rare earths, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi; x / y = 0.001-1.000; z / y = 2.2-3.0), where M is the element H, Cs, Rb, K, Tl, In, Ba, Li, Ca, Sr, Fe, and Sn are preferred, with Cs being particularly preferred. Particular preference is given to Ba 0.33 WO 3 , Tl 0.33 WO 3 , K 0.33 WO 3 , Rb 0.33 WO 3 , Cs 0.33 WO 3 , Na 0.33 WO 3 , Na 0.75 WO 3 , and mixtures thereof. In a particular embodiment of the present invention, the sole use of Cs 0.33 WO 3 as the inorganic IR absorber is particularly preferred.Cs / W ratios of 0.20 and 0.25 are also preferred.

[0075] Among the inorganic IR absorbers, woframates are preferable to borides due to their low inherent coloration, provided that the process according to the invention is to be carried out on plastic parts which have a radiation transmittance of ≥ 10% to ≤ 99%, preferably of ≥ 30% to ≤ 95%, particularly preferably ≥ 40% to ≤ 93% for the selected radiation, determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025 .

[0076] To produce such tungstates, tungsten trioxide, tungsten dioxide, a hydrate of a tungsten oxide, tungsten hexachloride, ammonium tungstate or tungstic acid and optionally further salts containing the element M, such as cesium carbonate, are mixed in certain stoichiometric ratios, so that the molar ratios of the individual components are represented by the formula M x W y O z This mixture is then treated at temperatures between 100 °C and 850 °C in a reducing atmosphere, e.g. an argon-hydrogen atmosphere, and finally the resulting powder is annealed at temperatures between 550 °C and 1200 °C under an inert gas atmosphere. To produce the inorganic IR absorber nanoparticles according to the invention, the IR absorber can be mixed with the dispersants described below and further organic solvents, such as toluene, benzene or similar aromatic hydrocarbons, and milled in suitable mills, such asBall mills, with the addition of zirconium oxide (e.g., with a diameter of 0.3 mm) are used to produce the desired particle size distribution. The nanoparticles are obtained in the form of a dispersion. After grinding, additional dispersants can be added if desired. The solvent is removed at elevated temperatures and reduced pressure. Nanoparticles with an average size of less than 200 nm, particularly preferably less than 100 nm, are preferred. The size of the particles can be determined using transmission electron spectroscopy (TEM). Such measurements on IR absorber nanoparticles are described, for example, in Adachi et al., J. Am. Ceram. Soc. 2008, 91, 2897-2902.

[0077] The preparation of the tungstates according to the invention is described in more detail in EP-A 1 801 815, for example, and they are commercially available, for example, from Sumitomo Metal Mining Co., Ltd. (Japan) under the name YMDS 874.

[0078] For example, for their use in plastic parts (A) comprising transparent thermoplastics with a radiation transmittance for the selected radiation of ≥ 10% to ≤ 99%, preferably of ≥ 30% to ≤ 95%, particularly preferably ≥ 40% to ≤ 93%, determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025, the particles thus obtained are dispersed in an organic matrix, e.g. in an acrylate, and optionally ground as described above in a mill using suitable auxiliaries such as zirconium dioxide and optionally using organic solvents such as toluene, benzene or similar hydrocarbons.

[0079] Suitable polymer-based dispersants are primarily dispersants that have a high transmission, such as polyacrylates, polyurethanes, polyethers, polyesters or polyester urethanes and polymers derived therefrom.

[0080] Preferred dispersants are polyacrylates, polyethers, and polyester-based polymers, with polyacrylates such as polymethyl methacrylate and polyester being particularly preferred as high-temperature-stable dispersants. Mixtures of these polymers or even acrylate-based copolymers can also be used. Such dispersing aids and methods for preparing tungstate dispersions are described, for example, in JP 2008214596 and in Adachi et al. J. Am. Ceram. Soc. 2007, pp. 4059-4061. Suitable dispersants are commercially available.

[0081] Polyacrylate-based dispersants are particularly suitable. Suitable dispersants of this type are available from Ciba Specialty Chemicals under the trade names EFKA™<, e.g., EFKA™< 4500 and EFKA™< 4530. Polyester-containing dispersants are also suitable. They are available, for example, under the trade names Solsperse™<, e.g., Solsperse™< 22000, 24000SC, 26000, 27000 from Avecia. Polyether-containing dispersants are also known, for example, under the trade names Disparlon™< DA234 and DA325 from Kusumoto Chemicals. Polyurethane-based systems are also suitable. Polyurethane-based systems are available from Ciba Specialty Chemicals under the trade names EFKA™< 4046 and EFKA™< 4047. Texaphor™< P60 and P63 are corresponding trade names of Cognis.

[0082] The amount of IR absorber in the dispersant can be from 0.2 wt.% to 50.0 wt.%, preferably from 1.0 wt.% to 40.0 wt.%, more preferably from 5.0 wt.% to 35.0 wt.%, and most preferably from 10.0 wt.% to 30.0 wt.%, based on the dispersion of the inorganic IR absorber used according to the invention. In addition to the pure IR absorber substance and the dispersant, the overall composition of the ready-to-use IR absorber formulation can also contain other auxiliaries such as zirconium dioxide, as well as residual solvents such as toluene, benzene, or similar aromatic hydrocarbons.

[0083] There are no restrictions regarding the amount of the inorganic IR absorbers according to the invention, particularly preferably those from the group of tungstates, in the polymer compositions of the plastic parts. Typically, the inorganic IR absorbers, in particular the tungstates, can be used in an amount of ≥ 0.7% by weight to ≤ 4.5% by weight, preferably ≥ 0.6% by weight to ≤ 2% by weight, and particularly preferably ≥ 0.7% by weight to ≤ 1.5% by weight, calculated as the solids content of inorganic IR absorber, in the overall polymer composition.

[0084] In this context, the solid content of inorganic IR absorber, in particular tungstate, means the inorganic IR absorber, in particular the tungstate, as a pure substance and not a dispersion, suspension or other preparation containing the pure substance, whereby the following information on the content of IR additive, in particular the tungstate content, always refers to this solid content, unless explicitly stated otherwise.

[0085] In a further embodiment, additional IR absorbers can optionally be used in addition to the tungstates as IR absorbers, although their proportion in such a mixture is in each case lower than that of the tungstates described above. For mixtures, compositions containing two to five, and particularly preferably two or three, different IR absorbers are preferred. The additional IR absorber is preferably selected from the group of borides and tin oxides, particularly preferably LaB6 or antimony-doped tin oxide or indium tin oxide.

[0086] Such mixtures of IR absorbers are predominantly used in applications where an inherent coloration of the component up to a Delta E of 20, preferably up to a Delta E of 15, can be accepted compared to the plastic part without IR absorber.

[0087] In an alternative embodiment of the invention, the plastic part can be coated with an additive in the form of a coating agent that exhibits an absorption maximum in the wavelength range of the focused non-ionizing electromagnetic radiation used. These coating agents preferably comprise an IR absorber that absorbs in the wavelength range from ≥ 0.70 µm to ≤ 1000 µm, preferably in the range from ≥ 1.0 µm to ≤ 50 µm, particularly preferably in the range from ≥ 1.0 µm to ≤ 2.5 µm. These coating agents are commercially available, for example, under the Clearweld™ brand name LD920, LD930, or LD940.

[0088] The at least one additive which has an absorption maximum in the wavelength range of the focused non-ionizing electromagnetic radiation used can be contained in the plastic part.

[0089] The dyeing bath (B) may comprise at least one colorant, preferably at least one dye, particularly preferably at least one dye from the group of solvent dyes and / or disperse dyes according to the Colour Index classification, or mixtures of these dyes.

[0090] The Colour Index (CI) of the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists uniquely characterises all colourants by the group name and the numbers for the chemical composition or chemical structure.

[0091] Dyes belonging to the solvent dye group according to the Color Index classification can include, for example, the so-called Macrolex™< dyes from Lanxess AG, Germany. Examples include Macrolex™< Blue 3R, Macrolex™< Red H, Macrolex™< Yellow 6G (Solvent Yellow 179 according to CI), Macrolex™< Violet Red R (Disperse Violet 31 according to CI), Macrolex™< Orange R (Solvent Orange 107 according to CI), or mixtures of these dyes.

[0092] Dyes in the Disperse Dye group according to the Colour Index classification can be, for example, diazo, diphenylamine, and anthraquinone compounds, acetate dyes, disperse dyes, and / or disperse dyes, and include Disperse Blue #3, Disperse Blue #14, Disperse Yellow #3, Disperse Red #134, and Disperse Red #7. The classification and designation of the dyes cited above are consistent with "The Colour Index," 3rd edition, jointly published by the Society of Dyes and Colors and the American Association of Textile Chemists and Colorists (1971). The dyes can generally be used either as the sole dye component or as a component of a mixture, depending on the desired color. Thus, the term "dye" used here also includes the dye mixture.

[0093] Suitable dyes include water-insoluble diazodiphenylamine and anthraquinone compounds. Particularly suitable are acetate dyes, dispersed acetate dyes, disperse dyes, and dispersol dyes, as disclosed in the Colour Index, 3rd Edition, Volume 2, The Society of Dyers and Colourists, 1971, pp. 2479 and 2187-2743, respectively.

[0094] The preferred dispersed dyes include Dystar's Palanil Blue E-R150 (anthraquinone / disperse blue), DIANIX Orange E-3RN (azo dye / Cl Disperse Orange 25) and the above-mentioned Macrolex™< dyes as solvent dyes.

[0095] In one embodiment, the dye bath comprises: a) Solvent and / or dispersant, preferably water and / or organic solvent, particularly preferably water b) Colorant, preferably a dye, particularly preferably a dye from the solvent dyes and / or disperse dyes according to the Colour Index classification.

[0096] Dyeing baths suitable for uniformly dyeing polycarbonate plastic parts at temperatures > 80 °C have proven advantageous. These are described, for example, in WO-A 03 / 040461, EP-A 2050866, and WO-A 03 / 083207. Under the conditions of the process according to the invention, the plastic part is essentially partially dyed in the irradiated areas, so that an intensive engraving becomes visible precisely at these locations.

[0097] In a further embodiment of the invention, the dye bath therefore comprises, in addition to the components a) and b) already mentioned, c) at least one further solvent according to the structural formula (IV) R-[(O-(CH 2 ) m ) n -]OH (IV), wherein R is an ethyl, propyl or butyl radical, m is 2, 3 or 4 and n is 1, 2 or 3, with the proviso that when R is butyl, m is 2 or 4, d) at least one levelling agent according to the structural formula (V): H-[(O-(CH 2 ) m ) n -]OH (V), wherein m is 2, 3 or 4 and n is 1, 2 or 3.

[0098] Components a) to d) may be contained in the following amounts based on the total weight of the dye bath: a) 50.0 to 99.99 wt.%, preferably 62.5 to 90.0 wt.%, particularly preferably 65.0 to 85.0 wt.%, b) 0.01 to 15.0 wt.%, preferably 0.1 to 5.0 wt.%, particularly preferably 0.2 to 4.0 wt.%, c) 0 to 35.0 wt.%, preferably 1.0 to 30.0 wt.%, particularly preferably 5.0 to 25.0 wt.%, d) 0 to 30.0 wt.%, preferably 1.0 to 20.0 wt.%, particularly preferably 3.0 to 15.0 wt.%.

[0099] Preferably, components a) to d) are contained in the dyeing bath in the following amounts, based on the total weight of the dyeing bath: a) 50.0 to 99.99 wt.%, preferably 62.5 to 90.0 wt.%, particularly preferably 65.0 to 85.0 wt.%, b) 0.01 to 25 wt.%, preferably 0.1 to 20 wt.%, particularly preferably 0.2 to 18 wt.%, c) 0 to 35.0 wt.%, preferably 1.0 to 30.0 wt.%, particularly preferably 5.0 to 25.0 wt.%, d) 0 to 30.0 wt.%, preferably 1.0 to 20.0 wt.%, particularly preferably 3.0 to 15.0 wt.%.

[0100] In a further embodiment of the process according to the invention, the dyeing bath comprises a dye and / or a dye mixture selected from the group of disperse dyes according to the Colour Index classification, very particularly a dye selected from the group consisting of azo, diphenylamine and anthraquinone compounds.

[0101] In another preferred embodiment of the process according to the invention, the dyeing bath comprises a dye and / or a dye mixture from the group of solvent dyes according to the Colour Index classification, very particularly preferably a dye and / or dye mixture of the Makrolex™ dyes.

[0102] Water and / or organic solvents can be used as solvent and / or dispersant a). Water is preferred.

[0103] All common solvents that do not attack the plastic part upon contact can be used as organic solvents. Examples include butyl alcohol, butylene glycol, diethylene glycol, ethyl alcohol, ethylene glycol, heptane, hexane, pentane, propargyl alcohol, propyl alcohol, or mixtures of the above.

[0104] Preferably, water and c) are used in the process according to the invention.

[0105] The irradiation of the plastic part (A) in step ii) is carried out with focused non-ionizing electromagnetic radiation, wherein the wavelength range of the focused non-ionizing electromagnetic radiation is selected such that the dye bath has a radiation transmittance of ≥ 2% to ≤ 99%, preferably ≥ 30% to ≤ 95%, particularly preferably ≥ 40% to ≤ 93% for the selected radiation, determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025

[0106] In an advantageous embodiment of the invention, the irradiation in step ii) is carried out with laser radiation having a wavelength in the range from ≥ 0.1 µm to ≤ 1000 µm, preferably from ≥ 1.0 µm to ≤ 50 µm, particularly preferably from ≥ 1.0 µm to ≤ 2.5 µm.

[0107] If laser irradiation is used, this can be done in continuous wave mode (CW laser). Pulsed laser radiation is particularly preferred for irradiating plastic parts. A laser pulse duration of just a fraction of a second is sufficient to color the plastic part at the laser-irradiated areas. Pulse durations of 10 -18 to 10 -1 seconds are preferred, with pulse durations of 10 -9 to 10 -2 seconds particularly preferred, and pulse durations of 10 -6 to 10 -3 seconds most preferred.

[0108] By varying the power of the laser beam used for irradiation in step ii), the intensity of the coloring at the lasered areas can be influenced, depending on the requirements of the desired application. The higher the laser power used, the more intense the coloring at the lasered areas of the plastic part. Sufficiently good colored engravings can be achieved with the medium power range of a 7.5-watt marking laser. Pulsed operation allows significantly higher power levels and thus more intense coloring in the plastic part.

[0109] By varying the frequency of the laser beam used for irradiation in step ii), it is possible to control whether the plastic surface is to be carbonized, and thus the creation of gray or black engravings, or whether the engraving should be in color, e.g. blue, magenta, yellow. NdYAG lasers (neodymium-doped yttrium aluminum garnet lasers) are preferably used in the process according to the invention to engrave plastic parts made of polycarbonate. At a pulse frequency of up to 25 kHz, gray engravings can still be achieved in plastic parts made of polycarbonate. At higher frequencies (> 25 kHz) and thus lower energy densities, the laser energy is no longer sufficient to achieve black or gray colors, but engraving in blue, magenta, or yellow can still be achieved at these energy densities.

[0110] NdYAG lasers (neodymium-doped yttrium aluminum garnet lasers) are preferably used in the process according to the invention. The shorter the pulses, the higher the peak pulse powers. With pulse lengths of 15 ns to 400 ns, pulse peaks of 100 kJ can be achieved. However, laser types suitable for engraving and welding plastics can also be used for color laser engraving of plastic parts. For example, a CO2 laser can also be used. This allows engraving to be performed preferably in blue, magenta, and yellow.

[0111] The color concentration of the dye bath can also influence the intensity of the partial coloring of the plastic part after irradiation. A colorant, preferably dye, concentration of 0.01 to 25 wt.%, preferably 0.1 to 20 wt.%, particularly preferably 0.2 to 18 wt.%, based on the total weight of the dye bath is preferred.

[0112] In one embodiment of the method according to the invention, a molded part made of plastic is used, which is produced in an injection mold according to known methods such as, for example, the in-mold decoration (IMD), film insert molding (FIM) or high-pressure forming (HPF) method.

[0113] In a further embodiment of the process according to the invention, the plastic part is a layered structure comprising at least one layer of a thermoplastic selected from polymers of ethylenically unsaturated monomers and / or polycondensates of bifunctional reactive compounds, preferably one or more polycarbonate(s) or copolycarbonate(s) based on diphenols, poly- or copolyacrylate(s) and poly- or copolymethacrylate(s), poly- or copolymer(s) with styrene, polyurethane(s), and polyolefin(s), poly- or copolycondensate(s) of terephthalic acid, poly- or copolycondensate(s) of naphthalenedicarboxylic acid, poly- or copolycondensate(s) of at least one cycloalkyldicarboxylic acid, or mixtures thereof, particularly preferably one or more polycarbonate(s) or copolycarbonate(s) based on diphenols or blends comprising at least one polycarbonate or copolycarbonate.

[0114] Most preferably, the at least one layer containing at least one thermoplastic is a film. This film preferably has a layer thickness of ≥ 1 µm to ≤ 1000 µm, preferably ≥ 5 to ≤ 800 µm, most preferably ≥ 10 to ≤ 500 µm.

[0115] To avoid repetition, reference is made below to the above statements on the thermoplastic material with regard to preferred embodiments, material, composition and additives.

[0116] In a further embodiment, the layer structure comprises at least one layer containing at least one thermoplastic as described above, and at least one further layer containing at least one thermoplastic as described above and at least one laser-sensitive additive, preferably a black pigment, particularly preferably carbon black. Such layer structures are known, for example, from WO-A 2010 / 089035 and are suitable for black-and-white laser engraving, in particular for the personalized laser engraving of security documents, and especially identification documents.

[0117] In another embodiment of the layer structure according to the invention, at least one layer containing at least one thermoplastic material can also comprise at least one filler. The filler is preferably at least one color pigment and / or at least one other filler for creating translucency in the filled layers, particularly preferably a white pigment, most preferably titanium dioxide, zirconium dioxide, or barium sulfate, and in a preferred embodiment, titanium dioxide.

[0118] Filling a layer containing at least one thermoplastic with at least one such filler improves the visibility of the applied inscription or image(s), thereby further increasing the perception of the improved sharpness and resolution. This layer structure is known from WO-A 2010 / 089035 and is described in detail therein.

[0119] In a further embodiment of the layer structure according to the invention, the layer structure can comprise at least one layer of a thermoplastic material and at least one additive which has an absorption maximum in the wavelength range of the focused non-ionizing electromagnetic radiation used, and wherein this at least one layer of a thermoplastic material has a radiation transmittance of ≥ 10% to ≤ 99%, preferably ≥ 30% to ≤ 95%, particularly preferably ≥ 40% to ≤ 93%, for the selected radiation, determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025, preferably an inorganic IR absorber, particularly preferably an inorganic IR absorber from the group of tungstates. This layer preferably forms an outer layer of the layer structure, which is ultimately also laser engraved in color.

[0120] In a further embodiment of the layer structure according to the invention, this comprises at least one outer layer of a thermoplastic containing at least one additive which has an absorption maximum in the wavelength range of the focused non-ionizing electromagnetic radiation used, and wherein this at least one layer of a thermoplastic has a radiation transmittance of ≥ 10% to ≤ 99%, preferably of ≥ 30% to ≤ 95%, particularly preferably ≥ 40% to ≤ 93%, for the selected radiation, determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025, preferably an inorganic IR absorber, particularly preferably an inorganic IR absorber from the group of tungstates, and a further layer containing at least one thermoplastic and at least one laser-sensitive additive, preferably black pigment,particularly preferably carbon black and optionally a further layer of a thermoplastic comprising a filler, preferably a white pigment, particularly preferably titanium dioxide, zirconium dioxide or barium sulfate, most preferably titanium dioxide.

[0121] This embodiment makes it possible, for example, to combine the colored laser engraving according to the invention with black laser engraving. For this purpose, the plastic part (A), comprising the layer structure described above, can be irradiated with C) either before step i) and / or after step ii) in the absence of the coloring bath (B) as in step ii). Ideally, the same radiation (C) can be used for this further irradiation. By irradiating with (C) in the absence of the coloring bath (B), a black engraving can be applied to the surface, preferably in underlying transparent and / or white layers of the layer structure at the desired location. The high laser reactivity of these layer structures leads to blackening at the laser-irradiated areas when laser engraved outside the coloring bath.If the layer structure is in the dyeing bath, the intensity of the laser beam is reduced by the dyeing bath so that only coloring occurs at the irradiated areas, but no blackening of the surface of the layer structure is caused.

[0122] In an alternative to the dyeing bath not according to the invention, the partial dyeing of the plastic part (A) can also be carried out by means of a dyeing layer b) containing at least one colorant, which is produced in a first step i').

[0123] Such an alternative method not according to the invention for the partial coloring, in particular colored laser engraving, of plastic parts, preferably of thermoplastic parts, most preferably of thermoplastic parts comprising a layer structure, comprises at least the steps: i') producing an at least partially covered colored layer b) on a plastic part (A); ii') irradiating the plastic part (A) from i') with non-ionizing electromagnetic radiation (C), wherein the partial coloring takes place essentially only at the locations covered with the colored layer b) in step i') or at the locations irradiated in step ii'), wherein the wavelength range of the non-ionizing electromagnetic radiation (C) is selected such that the colored layer b) has a radiation transmittance of ≥ 0.1% to ≤ 99%, preferably of ≥ 0.5% to ≤ 95%, particularly preferably ≥ 0.9% to ≤ 93% for the selected radiation, determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025.Before, during or after the irradiation in step ii), the plastic part (A) has a temperature in a range from ≤ 99 °C to ≥ -60 °C, preferably from ≤ 70 °C to ≥ -40 °C, particularly preferably from ≤ 50 °C to ≥ -15 °C, wherein the temperature of the plastic part (A) can vary within a temperature range of 100 °C during the duration of the process. The coloring layer b) preferably has a thickness of 0.001 mm to 10 mm, particularly preferably from 0.005 mm to 5 mm, very particularly preferably from 0.01 mm to 1 mm. The focused non-ionizing electromagnetic radiation (C) preferably passes through a plate (D) comprising one or more radiation-coupling materials before impinging on the plastic part (A).

[0124] Preferably, the non-ionizing electromagnetic radiation (C) is laser radiation having a wavelength in the range of ≥ 0.1 µm µm to ≤ 1000 µm, preferably in the range of ≥ 1.0 µm to ≤ 50 µm, particularly preferably in the range of ≥ 1.0 µm to ≤ 2.5 µm.

[0125] In step i') of the alternative process not according to the invention, the coloring layer b) is preferably applied as a solid or a liquid layer to the plastic part (A), such that the plastic part (A) is at least partially wetted with the coloring layer b). A solid layer can be produced by drying the liquid-applied coloring layer b). To apply a liquid layer to the plastic part (A), a process is preferably used selected from the group consisting of spraying, coating, pouring, dipping and printing, such as inkjet, screen printing, offset printing, gravure printing, doctor blade coating, gravure printing, pad printing or a combination of at least two thereof. In this alternative process, the partial coloring is achieved by applying colorant in the form of the color layer b) only at specific locations on the plastic part (A).The irradiation in step ii') can be carried out over part of the surface or the entire surface, depending on whether the colorant is applied to the entire surface or to part of the surface of the plastic part (A). Thus, if the colorant is applied in step i') in the form of the at least partially applied color layer b), the irradiation in step ii') is carried out over part of the surface. If the colorant is applied partially to the plastic part (A) in the form of the at least partially applied color layer b), the irradiation in step ii') can also be carried out over the entire surface. The colorant and its composition have already been described in connection with the first method according to the invention.

[0126] When the coloring layer b) is applied over the entire surface of the plastic part (A) in step i') and partially irradiated in step ii'), the non-irradiated portion of the coloring layer b) is preferably removed after step ii'). The removal of the coloring layer b) can be carried out, for example, in a water bath, assisted by ultrasonic cleaning, or by mechanical cleaning devices such as sponges or brushes, which can also be driven by a motor (rotation, oscillation, vibration, etc.).

[0127] The preferred ranges and embodiments for (A) to (E) described above in connection with the process according to the invention also apply, if present, to the alternative process not according to the invention and are equally applicable thereto. Therefore, reference is made to the above to avoid repetition.

[0128] The color concentration of the coloring layer can also influence the intensity of the partial coloring of the plastic part after irradiation. Coloring layer b) preferably has a colorant, preferably dye, concentration of 0.01 to 98 wt. %, preferably 0.1 to 50 wt. %, particularly preferably 0.2 to 25 wt. %, based on the total weight of coloring layer b).

[0129] The ink layer thickness is preferably precisely adjusted throughout the entire process and is preferably kept constant throughout the entire process to achieve partial coloring of high intensity and sharpness. The ink layer thickness is preferably 0.001 mm to 10 mm, more preferably 0.005 mm to 5 mm, and most preferably 0.01 mm to 1 mm.

[0130] A further subject matter of the invention is the security document defined in claim 15. In particular, the security documents personalized or color-engraved according to the method according to the invention are characterized by the high level of forgery security of the applied personalized or color-engraved information. Using the method according to the invention, blank documents can be personalized in color in a decentralized and forgery-proof manner. In addition, it is possible to create tactile laser engravings in color, which was previously only possible in black.

[0131] Plastic articles, in particular security and / or valuable documents, especially identification documents, can also be obtained using the alternative process not according to the invention. These documents are also characterized by a high level of forgery security due to the personalized or color-engraved information applied.

[0132] Another object of the invention is the device defined in claim 16.

[0133] In a preferred embodiment of the device, the temperature can vary during the duration of the process within a temperature range of 100°C, preferably 80°C, particularly preferably 50°C, further preferably 30°C, and more preferably 20°C. If the temperature does not vary by more than 10°C, it is considered a constant temperature.

[0134] The preferred ranges and embodiments described above for (A) to (E) also apply to the device. Therefore, reference is made to the above to avoid repetition. Figure 1 shows a possible embodiment of the device according to the invention for the partial coloring of two-dimensional plastic parts. Figure 2shows a possible embodiment of the device according to the invention for the partial coloring of three-dimensional plastic parts.

[0135] The reference symbols in Figures 1 and 2 are as follows: A-1: two-dimensional plastic part, preferably thermoplastic plastic part, particularly preferably thermoplastic plastic part comprising a layer structure A-2: three-dimensional plastic part, preferably thermoplastic three-dimensional plastic part B: dyeing bath or dyeing layer in liquid form C: focused non-ionizing electromagnetic radiation D: plate comprising one or more radiation-coupling materials E: radiation source for generating focused non-ionizing electromagnetic radiation b: immersion depth or dye layer thickness

[0136] In Figure 1a dyeing bath B is shown schematically, into which a two-dimensional plastic part A-1 is immersed such that at least one of its surfaces comes into contact with the colorant located in the dyeing bath B. Above the surface of the two-dimensional plastic part A-1 located in the dyeing bath B, at a well-defined distance b, also called immersion depth or dye layer thickness, there is a plate D comprising one or more radiation-coupling materials. During the method according to the invention, focused non-ionizing electromagnetic radiation C is directed from a radiation source for generating focused non-ionizing electromagnetic radiation E onto the surface of the plastic part A-1 in order to partially color the plastic part A-1.The dye bath B may have an outlet and an inlet for the dye so that fresh dye can be continuously introduced into the dye bath B, for example, to keep the dye bath B at a substantially constant temperature. The radiation source E may be arranged to be movable in at least two dimensions relative to the plastic part A-1 and the plate D so that different areas on the surface of the plastic part A-1 can be irradiated.

[0137] In the alternative process not according to the invention, the plate D is optional and the dyeing bath B can be in contact with the plastic part A-1 in such a way that only parts of the surface of the plastic part A-1 are covered with colorant.

[0138] In Figure 2 is a schematic diagram of an arrangement with a dye bath B, as in Figure 1which is suitable for irradiating a three-dimensional plastic part A-2. In contrast to the arrangement in Figure 1 Both the radiation source E and the plate D are arranged to be movable relative to the surface of the plastic part A-2, so that the radiation source E with the plate D can be moved in three dimensions relative to the plastic part A-2 in order to be able to carry out engravings on the three-dimensional plastic part A-2. Examples

[0139] Slide 1: Makrofol ™< ID4-4 opaque white, made of polycarbonate in a thickness of 300 µm from Covestro Deutschland AG.

[0140] Slide 2: Transparent polycarbonate film with IR absorber in a thickness of 100 µm was manufactured as follows: Masterbatch: Compounding of a highly concentrated IR masterbatch

[0141] The masterbatch for the production of film 2 was produced using a conventional twin-screw compounding extruder (ZSK 32) at processing temperatures of 250 to 330°C, which are typical for polycarbonate.

[0142] A master batch with the following composition was compounded and then granulated: 94.69 wt.% polycarbonate Makrolon ™< 3108 from Covestro Deutschland AG 0.75 wt.% YMDS 874 IR absorber from Sumitomo 4.5 wt.% Makrolon ™< 3108 powder from Covestro Deutschland AG 0.006 wt.% (60 ppm) lamp black 101 (carbon black from Evonik-Degussa GmbH) with an average particle size of 95 nm Production of extrusion film 2

[0143] The equipment used to produce the extruded film includes: an extruder for extruding the layer containing at least one polycarbonate with a screw of 60 mm diameter (D) and a length of 33 D. The screw has a venting zone; a melt pump; a deflection head; a slot die with a width of 450 mm; a three-roll smoothing calender with a horizontal roll arrangement, the third roll being pivotable by + / - 45° relative to the horizontal; a roller conveyor; a thickness measurement device; a device for applying protective film to both sides; a take-off device; a winding station.

[0144] The master batch granules were conveyed from the dryer into the extruder's hopper. The material was melted and conveyed in the extruder's barrel / screw plasticizing system. From the slot die, the melt flowed onto the smoothing calender. The film was finally shaped and cooled on the smoothing calender (consisting of three rolls). A textured steel roll (6-side) and a textured silicone rubber roll (2-side) were used to emboss the surfaces. The rubber roll used for structuring the film surface is disclosed in US Pat. No. 4,368,240, issued to Nauta Roll Corporation. The film was then transported through a take-off and then wound up. Lamination of films 1 and 2 to laminate A or A':

[0145] Lamination was performed on a Bürckle Model 50 / 100 laminating press. Films 1 and 2 were laminated using the following press settings: Preheat the press to 170-180 °C Press for 8 minutes at a pressure of 15 N / cm 2< Press for 2 minutes at a pressure of 100 N / cm 2< Cool the press to 38 °C and open the press. Composition of the dye bath for Example 1 and 2

[0146] 69.31 wt% water 0.99 wt% Macrolex™< Blue 3R (dye, from Lanxess AG Germany) 19.8 wt% ethylene glycol butyl ether (EGBE), (solvent, The Dow Chemical Company) 9.9 wt% parts diethylene glycol (DEG), (leveling agent, Merck KGaA) Composition of the staining solution for producing the staining layer

[0147] 30 wt% water 20 wt% Macrolex ™< Blue 3R (dye, from Lanxess AG Germany) 50 wt% isopropanol) Example 1 (comparison):

[0148] The laminate A was placed (transparent side (foil 2) facing upwards) in the dyeing bath (B) of the above composition.

[0149] For laser irradiation, a NdYAG laser from Foba, model D84, with a laser power of approximately 7.5 watts, a laser frequency of 8 kHz in pulsed mode, and a current of 30 A was used. The feed speed of the laser, immersion depth, and the temperature of the dye bath (B) are given in Table 1.

[0150] The dye bath containing the film was placed on the workpiece carrier of a Foba D84S laser system. The laser focus (E) was adjusted to the film surface. The immersion depth is shown in Table 1. For the purposes of this invention, immersion depth refers to the penetration depth of the radiation used into the dye bath down to the surface of the plastic part to which the partial dyeing was to be applied. The part was irradiated with the laser beam. Table 1: Conditions of color laser engraving Temperature of the dye bath 40 °C Diving depth 1 mm feed rate 100 mm / s

[0151] After laser irradiation (E), laminate A was removed from the dye bath, and the quality of the laser engraving was visually assessed. The engraving was uneven in terms of color intensity and sharpness of the typeface. Example 2 (according to the invention according to the process according to claim 1 (laminate A) or according to the alternative process (laminate A'))

[0152] Laminate A (A-1) was placed (transparent side (film 2) facing up) in the dye bath (B) of the above-mentioned composition. Laminate A' was coated with a dye layer by printing.

[0153] A 3 mm thick silicate glass plate (D) was placed on top of laminate A. Spacers were used to maintain a distance of 1 mm (immersion depth) between laminate A and glass plate (D). The dye bath (B) was filled so that the top surface of the glass plate (B) remained free of dyeing fluid.

[0154] The laminate A' was clamped into a holder.

[0155] For laser irradiation, a NdYAG laser from Foba, model D84, with a laser power of approximately 7.5 watts, a laser frequency of 8 kHz for laminate A or 30 kHz for laminate A' in pulsed mode, and a current of 30 A was used. The feed speed of the laser, immersion depth or ink layer thickness (b), and the temperature of the dye bath (B) are given in Table 2.

[0156] The focus of the laser (E) was adjusted through the glass plate onto the film surface of laminate A'. For the purposes of this invention, the immersion depth or color layer thickness (b) refers to the penetration depth of the radiation used into the coloring bath (B) or into the coloring layer (b) down to the surface of the plastic part to which the partial coloring was to be applied. The part was irradiated with the laser beam. Table 2: Conditions of color laser engraving Temperature of the dye bath for laminate A or the dye layer for laminate A' 40 °C Immersion depth or paint layer thickness 1 or 0.3 mm defined by the distance between laminate and glass plate or thickness of the dye layer Feed rate in the method according to claim 1 or alternative method 100 or 50 mm / s

[0157] After laser irradiation, laminate A was removed from the dye bath (B), and the unexposed ink layer of laminate A' was removed in a water bath using a sponge. The quality of the laser engraving was then visually assessed. The engraving of both laminate A and laminate A' was significantly more uniform in terms of color intensity and sharpness of the typeface compared to Example 1.

Claims

1. Process for partial colouring of plastic parts, comprising the steps of i) immersing a plastic part (A) in a colouring bath (B), ii) irradiating the plastic part (A) from i) with focused nonionizing electromagnetic radiation (C), wherein the partial colouring is effected substantially only at the sites irradiated in step ii), wherein the wavelength range of the focused nonionizing electromagnetic radiation (C) is chosen such that the colouring bath (B) has a radiation permeability of ≥ 2% to ≤ 99%, preferably of ≥ 30% to ≤ 95%, particularly preferably of ≥ 40% to ≤ 93%, for the chosen radiation determined by the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025, wherein the colouring bath (B) has a temperature of ≤ 99°C to ≥ -60°C, preferably of ≤ 99°C to ≥ 0°C, more preferably of ≤ 70°C to ≥ 10°C, particularly preferably of ≤ 50°C to ≥ 15°C, wherein the temperature of the colouring bath (B) preferably has a constant temperature over the duration of the process, characterized in that the focused nonionizing electromagnetic radiation (C) passes through a sheet (D) comprising one or more radiation-decoupling materials before impacting the plastic part (A).

2. Process according to Claim 1, wherein the focused nonionizing electromagnetic radiation (C) is laser radiation having a wavelength in the range from ≥ 0.1 µm to ≤ 1000 µm, preferably in the range from ≥ 1.0 µm to ≤ 50 µm, particularly preferably in the range from ≥ 1.0 µm to ≤ 2.5 µm.

3. Process according to Claim 1 or 2, wherein the distance of the sheet (D) from the surface of the plastic part (A) is ≤ 120 mm, preferably ≥ 0.01 to ≤ 100 mm, particularly preferably ≥ 0.1 to ≤ 20 mm and very particularly preferably ≥ 0.1 to ≤ 5.0 mm.

4. Process according to any of Claims 1 to 3, wherein the radiation-decoupling material(s) of the sheet (D) exhibit(s) a scratch-dig value of ≥ 80-50 to ≤ 10-10, preferably of ≥ 60-40 to ≤ 20-10, determined according to ISO10110-8, a surface roughness Rq determined according to ISO 10110-8 of ≥ 0.5 to ≤ 500 nm, preferably of ≥ 0.7 to ≤ 100 nm, particularly preferably of ≥ 1nm to ≤ 10 nm, and a radiation permeability of ≥ 50% to ≤ 99.95%, preferably of ≥ 60% to ≤ 99.9%, particularly preferably of ≥ 70% to ≤ 99.89%, for the chosen radiation determined according to the UV-VIS-NIR-MIR method according to DIN EN ISO / IEC 17025.

5. Process according to any of Claims 1 to 4, wherein the radiation-decoupling material(s) of the sheet (D) comprise(s) at least one or more compounds from the group of glass, radiation-permeable plastic, mineral glass, synthetic glass, radiation-permeable ceramic material and / or mixtures of at least two of the abovementioned compounds.

6. Process according to any of Claims 1 to 5, wherein the plastic part (A) contains a thermoplastic plastic selected from polymers of ethylenically unsaturated monomers and / or polycondensates of bifunctional reactive compounds and / or polyaddition products of bifunctional reactive compounds.

7. Process according to any of Claims 1 to 6, wherein the plastic part (A) comprises at least one additive which has an absorption maximum in the wavelength range of the employed focused nonionizing electromagnetic radiation or wherein the plastic part is coated with at least one additive in the form of a coating composition which has an absorption maximum in the wavelength range of the employed focused nonionizing electromagnetic radiation.

8. Process according to Claim 7, wherein the additive comprises at least one or more organic and / or inorganic IR absorbers.

9. Process according to any of Claims 1 to 8, wherein the colouring bath (B) comprises at least one colorant, preferably at least one dye, or mixtures thereof.

10. Process according to any of Claims 1 to 9, wherein the colouring bath (B) comprises at least one dye from the group of solvent dyes and / or disperse dyes according to the Colour Index classification or mixtures of these dyes.

11. Process according to any of Claims 1 to 10, wherein the colouring bath (B) comprises: a) solvent and / or dispersant, preferably water and / or organic solvent, b) at least one colorant, preferably at least one dye, particularly preferably at least one dye from the solvent dyes and / or disperse dyes according to the Colour Index classification or a mixture of the abovementioned dyes.

12. Process according to any of Claims 1 to 11, wherein the plastic part (A) contains a layer construction, wherein this layer construction comprises at least one layer of a thermoplastic plastic.

13. Process according to Claim 12, wherein the layer construction comprises at least one layer containing at least one thermoplastic plastic and at least one further layer containing at least one thermoplastic plastic and at least one black pigment, preferably carbon black.

14. Process according to Claim 13, wherein said process comprises irradiating with focused nonionizing electromagnetic radiation (C) as in step ii) in the absence of the colouring bath before step i) and / or after step ii).

15. Security document comprising a plastic part partially coloured by the process according to any of Claims 1 to 14.

16. Apparatus for performing the process according to any of Claims 1 to 14 comprising a colouring bath (B), a sheet (D) comprising one or more radiation-decoupling materials and a radiation source (E) for producing a focused nonionizing electromagnetic radiation (C), wherein the colouring bath (B) preferably has a temperature of ≤ 99°C to ≥ -60.0°C, more preferably of ≤ 99°C to ≥ 0.0°C, preferably of ≤ 70°C to ≥ 10°C, particularly preferably of ≤ 50°C to ≥ 15°C, wherein the temperature may vary in a temperature range of 100°C or remains constant upon startup of the apparatus, characterized in that the focused nonionizing electromagnetic radiation (C) passes through the sheet (D) comprising one or more radiation-decoupling materials before impacting the plastic part (A).

17. Apparatus according to Claim 16, wherein the colouring bath (B) has a temperature of ≤ 99°C to ≥ - 60°C, preferably of ≤ 99°C to ≥ 0°C, more preferably of ≤ 70°C to ≥ 10°C, particularly preferably of ≤ 50°C to ≥ 15°C, wherein the temperature preferably remains constant upon startup of the apparatus.