EP1856199B1 - Plastic moulding with bidimensional or tridimensional image structures generated by inner laser engraving - Google Patents

Abstract

Plastic mouldings are disclosed with bidimensional or tridimensional image structures generated by inner laser engraving on their inside. The plastic mouldings are made of plastic materials with a content of nanoscale metal oxides having a particle size ranging from 1 to 500 nm. Both the plastic material and the metal oxide contained therein are transparent to the laser light used to generate the image structures. The plastic materials of which the mouldings are made contain, in particular, 0.001 to 0.1 % by weight metal oxides with a particle size ranging from 5 to 100 nm. Typical metal oxides are nanoscale indium tin oxide or antimony tin oxide.

Description

The invention relates to plastic moldings with two- or three-dimensional image structures produced internally by internal laser engraving, wherein the plastic moldings consist of plastic materials which have a content of nanoscale metal oxides with a particle size of 1 to 500 nm, and both the plastic material and the metal oxide contained the laser light used to generate the image structures is transparent.

The introduction of optical information in plastic materials by laser radiation is known per se. A distinction is made between laser marking and laser engraving.

The marking of plastics by laser marking acts on the object surface or in the near-surface region. Decisive here is the absorption of the laser energy in the plastic material by direct interaction with the polymer or with an additive added to the plastic material, such as an organic dye or an inorganic pigment which absorbs the laser radiation. In any case, the absorption of the laser energy causes a chemical change in the material and thus a visible local discoloration of the plastic.

The laser markability is dependent on the wavelength-specific absorption behavior of the plastic materials or of the polymers on which they are based, of the wavelength-specific Absorption behavior of any laser-sensitive additives as well as the wavelength and radiation power of the laser radiation to be used. In addition to CO ₂ and excimer lasers, Nd: YAG lasers (neodymium-doped yttrium-aluminum Garnet lasers) with the characteristic wavelengths of 1064 nm and 532 nm are increasingly being used in this technique.

Laser-markable plastic materials which contain laser-sensitive additives in the form of dyes and / or pigments generally have a more or less pronounced coloring and / or lack of transparency. Often, the equipment is to be set as laser-absorbing molding compounds by the introduction of carbon black.

Highly transparent plastic materials which can be made laser markable by adding nanoscale laser absorbing metal oxides are known in the art German utility model 20 2004 003362.3 and in the not pre-published German patent application 10 2004 010504.9 described.

For the technology of the interior engraving of transparent to laser radiation glasses and plastics by laser beams are exemplary the writings DE 44 07 547 and US 5,206,496 called.

In contrast to the laser marking, the laser engraving has to work in any depth of the material. This presupposes that the material is essentially transparent to the incident laser radiation, since otherwise it would already be absorbed in the surface region.

When focusing a laser beam of sufficiently high power density into the interior of the material which is transparent to the laser light, optical effects cause a limited development of thermal energy in the laser focus.

This heat development results in locally limited microcracking in the material. Such microcracks have a dot diameter of 25-40 microns. In visible light transparent glasses and plastics, the microcracks appear as bright spots due to the scattering of daylight at the crack edges.

By deflecting the laser radiation via mirrors and the movement of the workpiece as well as by a synchronization between the movement sequence and the laser pulses corresponding structures can be composed of individual microcracks in the workpiece.

The pulse repetition frequency of the lasers typically used in this case allows the generation of structures with up to about 1000 points per minute.

The starting point is a 3D representation of the later motif in a CAD program. The surface or the entire structure of the model is computationally resolved as a point cloud whose individual points are converted by the laser beam in the glass or plastic as microcracks. The denser the point cloud through which the object is displayed, the more accurate and clean the model is mapped.

In the laser engraving of plastics with laser light, for which the plastic is actually transparent, a marking is generated in the interior of the material in the form of microcracks by appropriate focusing of the laser beam. This can lead to uncontrolled cracking and crack propagation. This is a weakening of the material. Therefore, it should be attempted to minimize this weakening.

In glass, this cracking can even lead to a subsequent destruction of the molding, some of which only days or even weeks after the laser engraving occurs.

In plastics, in addition to the cracking, a local destruction of the material and carbonization may additionally occur, which is undesirable in the interior engraving of materials that are transparent in visible light because of the dark discoloration.

Another problem of laser engraving with methods and materials according to the prior art is the insufficient imaging accuracy in detailed, filigree patterns, both in glass and in plastics. Theoretically one can improve the imaging accuracy by increasing the dot cloud density. In practice, however, the dots run into each other at a certain point density due to the uncontrolled propagation of cracks and are no longer resolved, so that the imaging accuracy even suffers.

In US 5,761,111 describes a method for crack-free internal laser engraving by laser pulses in the femtosecond range. However, suitable lasers for technical use are not yet available and would also be very expensive.

In US 6,537,479 the problem of cracking is circumvented by performing the laser marking in the plasticized state of the material and either leaving the object in that state (enveloped by a solid protective wrapper) or subsequently curing it. This method is very complex and also limited in the case of subsequent curing on materials that show no shrinkage during curing, otherwise the filigree geometry of the laser engraving would be destroyed again. On the common in technical application polymer materials, this method is only conditionally applicable and then with considerable additional effort.

The present invention therefore an object of the invention to find plastic materials and to provide two-dimensional or three-dimensional image structures with significantly improved imaging accuracy by means of laser engraving while avoiding uncontrolled cracking and crack propagation. In this case, the commercially available commercially available laser sources should be used.

Surprisingly, it has been found that in the interior of plastic moldings, which consist of plastic materials which have a content of nanoscale metal oxides with a particle size of 1 to 500 nm, three-dimensional image structures of the highest fineness and detail can be produced by means of internal laser engraving, if laser light is used for that both the plastic material and the metal oxide contained is transparent, irradiated by imaging.

The invention thus relates to plastic moldings with two- or three-dimensional image structures produced in the interior by internal laser engraving, which are characterized in that the plastic moldings consist of plastic materials which have a content of nanoscale metal oxides with a particle size of 1 to 500 nm, wherein both the Plastic material and the metal oxide contained is transparent to the laser light used to generate the image structures.

The invention further relates to a process for the production of two- or three-dimensional image structures in the interior of plastic moldings by internal laser engraving, in which moldings consisting of plastic materials having a content of nanoscale metal oxides with particle size of 1 to 500 nm, with Laser light for which both the plastic material and the metal oxide contained is transparent, imagewise irradiated.

Transparent plastic materials should be understood as meaning those which are essentially transparent in a wavelength range of 300 to 1300 nm. On the one hand, the visible wavelength range of 400 to 800 nm is preferred. Corresponding materials are particularly suitable for introducing visually perceptible structures by internal laser engraving, for example in the form of art objects. On the other hand, plastic materials with laser transparency in the wavelength range from 800 to 1300 nm are preferred. Corresponding materials, which may also appear colored and / or opaque or completely opaque in their visual appearance, are suitable for introducing visually imperceptible structures by internal laser engraving. for example as bar codes or data matrix codes for, for example, security purposes.

The transmission of the plastic material in the selected wavelength range of typically commercially used, commercially available laser sources should be greater than 80%, preferably greater than 85% and particularly preferably greater than 90%. The haze in the wavelength range from 400 to 800 nm should be less than 5, preferably less than 2 and in particular less than 1%. The determination of transmission and haze is carried out according to ASTM D 1003.

Nanoscale metal oxides are understood as meaning all inorganic-metallic oxides, such as metal oxides, mixed metal oxides, complex oxides and mixtures thereof, which cause little or no absorption in the characteristic wavelength range of the laser to be used.

Overall, care must be taken to ensure that both the transparent molded plastic body and the nanoscale metal oxide are transparent to the laser light to be used.

By nanoscale is meant that the largest dimension of the discrete particles of these laser-sensitive metal oxides less than 1 pm, that is in the nanometer range. This size definition refers to all possible particle morphologies such as primary particles as well as any aggregates and agglomerates.

The particle size of the laser-sensitive metal oxides is preferably from 1 to 500 nm and in particular from 5 to 100 nm. If the particle size is below 100 nm, the metal oxide particles are no longer visible per se and do not impair the transparency of the plastic matrix.

In the plastic material, the content of inorganic nanoparticles is suitably 0.0001 to 0.1 wt.%, Preferably 0.0005 to 0.05 wt.% And particularly preferably 0.001 to 0.01 wt.%, Based on the plastic material. In this concentration range, a controlled crack formation and thus a visible depth marking with high imaging accuracy is usually and for all eligible plastic materials effected.

With a suitable choice of particle size and concentration in the specified ranges, an impairment of the intrinsic transparency is excluded even in the case of highly transparent matrix materials in the visible wavelength range. Thus, it is expedient for nanoparticles with particle sizes above 100 nm to choose the lower concentration range, while at particle sizes below 100 nm, higher concentrations can also be selected.

Suitable inorganic nanoparticles for the production of laser-deep-markable plastic materials are preferably doped indium oxide, doped tin oxide, doped zinc oxide, doped aluminum oxide, doped antimony oxide and corresponding mixed oxides.

Even with opaque plastic materials, which are irradiated in the wave range between 800 and 1300 nm nano particles with particle sizes of less than 100 nm are usefully used, since a homogeneous distribution of the metal oxides in the polymer matrix can be achieved, which is crucial for controlled crack formation.

Particularly suitable inorganic nanoparticles are indium tin oxide (ITO) or antimony tin oxide (ATO) and doped indium or antimony tin oxides. Indium tin oxide is particularly preferred, and in turn, the "blue" indium tin oxide obtainable by a partial reduction process. The unreduced "yellow" indium tin oxide may cause a visually perceptible slightly yellowish hue of the plastic material at higher concentrations and / or particle sizes at the top, while the "blue" indium tin oxide will not cause any discernible color change. At most, a faint blueness is observed, which is regarded by the viewer but rather as high quality, as a yellow cast.

The inorganic nanoparticles to be used according to the invention are known per se and are also commercially available in nanoscale form, that is to say with particle sizes of less than 1 μm, and in particular in the size range preferred here, often in the form of dispersions. As supplied, the inorganic nanoparticles are generally agglomerated. The agglomerates, whose particle size is between 1 .mu.m and several mm, can be broken down into nanoscale particles by means of strong shearing. The determination of the Agglomerationagrades takes place in the sense of DIN 53206 (from August 1972).

Nanoscale metal oxides can be prepared, for example, by pyrolytic processes. Such methods are for example in EP 1 142 830 A . EP 1 270 511 A or DE 103 11 645 described. Furthermore, inorganic nanoparticles can be prepared by precipitation processes, such as in DE 100 22 037 described.

The nanoscale metal oxides can be incorporated into virtually any plastic system to impart laser markability. Typical are plastic materials in which the plastic matrix on poly (meth) acrylate, polyamide, polyurethane, polyolefins, styrene polymers and styrene copolymers, polycarbonate, silicones, polyimides, polysulfone, polyethersulfone, polyketones, polyether ketones, PEEK, polyphenylene sulfide, polyester (such as PET, PEN, PBT ), Polymethylene oxide, polyurethane, polyolefins or fluorine-containing polymers (such as PVDF, EFEP, PTFE). It is also possible to incorporate them into blends containing the above-mentioned plastics as components, or into polymers derived from these classes which have been modified by subsequent reactions. These materials are widely known and commercially available. The advantage of the inorganic nanoparticles according to the invention is in particular in highly transparent plastic systems such as polycarbonates, transparent polyamides (for example Grilamid® TR55, TR90, Trogamid® T5000, CX7323), polyethylene terephthalate, polysulfone, polyethersulfone, cycloolefin copolymers (Topas®, Zeonex®), polymethyl methacrylate and their copolymers because they do not affect the transparency of the material. Furthermore, transparent polystyrene and polypropylene are to be mentioned, furthermore all semicrystalline plastics which can be processed by the use of nucleating agents or special processing conditions to transparent moldings.

The transparent polyamides of the invention are generally prepared from the building blocks: branched and unbranched aliphatic (6 C to 14 C atoms), alkyl-substituted or unsubstituted cycloaliphatic (14 C to 22 C atoms), araliphatic diamines (C14 - C22) and aliphatic and cycloaliphatic dicarboxylic acids (C6 to C44); The latter can be partly due to aromatic Dicarboxylic acids are replaced. In particular, the transparent polyamides can additionally consist of monomer units with 6 C atoms, 10 C atoms, 11 C atoms or 12 C atoms, which are derived from lactams or ω-aminocarboxylic acids.

Preferably, but not exclusively, the transparent polyamides of the invention are prepared from the following building blocks: laurolactam or ω-aminododecanoic acid, azelaic acid, sebacic acid, dodecanedioic acid, fatty acids (C18-C36, eg under the trade name Pripol®), cyclohexanedicarboxylic acids, partial or partial replacement thereof aliphatic acids by isoterephthalic acid, terephthalic acid, naphthalenedicarboxylic acid, tributylisophthalic acid. Furthermore, the use of decanediamine, dodecanediamine, nonanediamine, hexamethylenediamines branched, unbranched or substituted, as well as representatives of the class of alkyl-substituted / unsubstituted cycloaliphatic diamines bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) - methane, bis (4-aminocyclohexyl) propane, bis (aminocyclohexane), bis (aminomethyl) cyclohexane, isophoronediamine or substituted pentamethylenediamines.

Examples of corresponding transparent polyamides are approximately in EP 0 725 100 and EP 0 725 101 described.

Highly transparent plastic systems based on polymethyl methacrylate, bisphenol A polycarbonate, polyamide and so-called cycloolefin copolymers of norbornene and α-olefins which can be made laser-marked with the aid of the inorganic nanoparticles according to the invention without impairing the transparency of the material are particularly preferred.

Of course, the nanoscale metal oxides can also be used in colored high-transparency systems become. Here is particularly advantageous that the neutral color of these additives allows a free choice of color.

The transparent plastic materials which can be structured according to the invention by internal laser engraving can be present as plates, shaped bodies, semi-finished products or molding compositions. In this case, only a part of the plates, moldings, semi-finished products and molding compounds can be set laser-engravable inside.

The production of the laser-engravable plastic materials is carried out in a conventional manner according to common in plastics production and processing techniques and methods. It is possible to enter the nanoparticulate additives before or during the polymerization or polycondensation into individual starting materials or Eduktgemische or even during the reaction, wherein the known in the art specific manufacturing process for the plastics in question are used. In the case of polycondensates such as polyamides, for example, incorporation of the additive into one of the monomer components can take place. This monomer component can then be subjected to a polycondensation reaction in the customary manner with the other reaction partners. Furthermore, after the formation of macromolecules, the resulting high molecular weight intermediates or end products can be mixed with the nanoparticulate additives, it also being possible in this case for all methods familiar to the person skilled in the art to be used.

Depending on the formulation of the plastic matrix material liquid, semi-liquid and solid formulation ingredients or monomers and optionally required additives such as polymerization initiators, stabilizers (such as UV absorbers, heat stabilizers), optical brighteners, Anstistatika, plasticizers, mold release agents, lubricants, dispersing aids, antistatic agents but also Fillers and reinforcing agents or impact modifiers, etc. in customary devices and equipment such as reactors, stirred tanks, mixers, roll mills, extruders, etc. blended and homogenized, optionally shaped and then cured. The nanoscale metal oxides are introduced into the material at the appropriate time and homogeneously incorporated. Particularly preferred is the incorporation of the nanoscale metal oxides in the form of a concentrated masterbatch with the same or a compatible plastic material.

It is advantageous if the incorporation of the nanoscale metal oxides in the plastic matrix takes place under high shear in the plastic matrix. This can be done by appropriate adjustment of the mixer, roller mills, extruder. This effectively prevents any agglomeration or aggregation of the nanoscale metal oxide particles into larger units; any larger particles that are present are comminuted. The skilled worker is familiar with the corresponding techniques and the respective process parameters to be selected.

Plastic moldings and semi-finished products are obtainable by injection molding or extruding from molding materials or by casting from the monomers and / or prepolymers.

The polymerization is carried out by methods known to the person skilled in the art, for example by adding one or more polymerization initiators and inducing the polymerization by heating or irradiation. For the complete conversion of the monomer or monomers, an annealing step can follow the polymerization.

After production of plastic moldings from the nano-scale metal oxides containing plastic materials can be marked by irradiation with laser light.

Laser engraving may be performed on a commercially available laser marking device, e.g. Cerion (Cerion X2, compact, green 532 nm) with a writing speed of 300 to 1000 points / s, a pulse frequency of 3 kHz and a pulse energy of 1 to 2 mJ are performed. The shaped bodies to be engraved are placed in the device and, after irradiation with a focused laser beam, obtain white to dark gray image structures with sharp contours and high contrast. The required settings can be determined in individual cases without further ado.

• Ti:Al203 (Wellenlänge einstellbar von 680 bis 1100 nm)
• Yb:YAG (Wellenlänge 1030 nm, 1. Oberschwingung: 515 nm, 2. Oberschwingung: 343 nm)
• Nd: YAG und Nd:Ce:Tb:YAG (Wellenlänge 1064 nm, 1. Oberschwingung: 532 nm, 2. Oberschwingung: 355 nm)
• Ho:Cr:Tm:YAG (Wellenlänge 2097 nm, 1. Oberschwingung: 1048,5 nm, 2. Oberschwingung: 699 nm)
• Er:YAG (Wellenlänge 2940 nm, 1. Oberschwingung: 1470 nm, 2. Oberschwingung: 980 nm)

As laser crystals, for example, the following materials may also be used:

• Ti: Al 2 O 3 (wavelength adjustable from 680 to 1100 nm)
• Yb: YAG (wavelength 1030 nm, 1st harmonic: 515 nm, 2nd harmonic: 343 nm)
• Nd: YAG and Nd: Ce: Tb: YAG (wavelength 1064 nm, 1st harmonic: 532 nm, 2nd harmonic: 355 nm)
• Ho: Cr: Tm: YAG (wavelength 2097 nm, 1st harmonic: 1048.5 nm, 2nd harmonic: 699 nm)
• Er: YAG (wavelength 2940 nm, 1st harmonic: 1470 nm, 2nd harmonic: 980 nm)

Of course, diode lasers emitting at wavelengths of 808, 940 and 980 nm can also be used.

According to the invention, the transparent plastic materials can be used very advantageously for the production of plastic moldings having three-dimensional image structures produced below the surface by internal laser engraving. In addition to technical applications, in particular, artistic objects can be realized.

The transparent polymers can also be colored. It makes sense to use colors that match the laser light do not absorb. The coloring can be transparent, translucent but also covered.

Particularly interesting art objects are obtained when fluorescent dyes are used. By illuminating the edges of such art objects particularly valuable appearing art objects can be produced.

In the following, the preparation of the nanoparticles / plastic mixtures and the performance of the internal engraving by laser depth marking will be explained by way of example on polymethyl methacrylate and polyamide systems.

Example 1: Production of a cast polymethyl methacrylate block (PLEXIGLAS® GS) with 100 ppm indium tin oxide 1. Dispersion of indium tin oxide Nano® ITO IT-05 C5000 from Nanogate in PMMA molding compound PLEXIGLAS® 7N on a two-roll mill Polymix 110 L from Schwabenthan:

90g PMMA molding compound PLEXIGLAS® 7N are melted on the preheated two-roll mill. The roller temperature is 166 ° C at the front roller and 148 ° C at the rear roller. An additional 90 g of PLEXIGLAS® 7N PMMA molding compound are premixed with 20 g of Nano® ITO IT-05 C5000 and applied to the rollers with about 5 g of stearic acid. The rear roller is rotated a little faster, creating a friction. Within 6 minutes, the rolled sheet is pulled off the roll 10 times, folded and returned to the roll. Then you pull the roller skin from the roller, allowed to cool and crushed.

2. Preparation of a stock solution with the rolled skin:

Weigh into a 11 wide mouth bottle: 50.0 g 10% rolled skin (from 1.) 87.5 g Dispersant (eg PLEX® 8684 F from AG / Röhm) DEGUSSA 750.0 g MMA 750.0 g MMA / PMMA syrup with 25% PMMA with MW of 170000

To loosen the roller skin and the polymeric dispersant, the bottle is closed and rolled on a roll bar for 50 hours.

3. Preparation of the polymerization batch:

Preparation of the polymerization batch of 1000 g with 0.01% Nano® ITO IT-05 C5000. 34.50 g stock solution 0.80 g Initiator (2,2'-azobis (2,4-dimethylvaleronitrile) 0.20 g up to 1.0 g release agent (lecithin) 960.00 g MMA / PMMA syrup with 25% PMMA with MW of 170000

The polymerization mixture is stirred for 30 min, allowed to stand for 10 min, filled into the polymerization and then immediately placed in a water bath.

4. Polymerization in a polymerization chamber

From two 6mm thick float glass panes, a spacer cord and some metal clips, a polymerization chamber size of 10 x 200 x 200 mm size is built. The polymerization is set up vertically, allowed to run slowly the polymerization mixture and sealed the chamber. The filled polymerization chamber is placed horizontally in the heated to 45 to 50 ° C water bath and left so long until the polymerization is polymerized to a solid mass. After removal of the clamps and the Distanzierschnur the polymerization is 4h end polymerized in a pre-heated to 115 ° C tempering, then allowed to cool in a tempering and removed from the mold.

Visible light transmission is 90% and Haze 1%.

The material was laser-marked with a frequency-doubled Nd: YAG laser (emission wavelength 532 nm power level 3, duration 4 min).

Comparative Example 2: Production of an undoped cast polymethyl methacrylate block (PLEXIGLAS® GS)

The procedure is analogous to the procedure of Example 1. Only the process steps 3 and 4 are carried out. On the production of a rolled sheet can be omitted. The appropriate amount of stock solution from step 3 can be replaced by an appropriate amount of MMA / PMMA syrup.

Visible light transmission is 90% and Haze 1%.

The material was laser-marked with a frequency-doubled Nd: YAG laser (emission wavelength 532 nm, power level 3, duration 4 min).

Example 3: Production of a polyamide / ITO compound

Trogamid® CX 7323, a commercial product of Degussa AG, Business Unit High Performance Polymers, Marl, is coated with nanoscale indium tin oxide Nano®ITO IT-05 C5000 from Nanogate in a concentration of 0.01% by weight on a Berstorff ZE 2533 D extruder Compounded at 300 ° C and granulated. From the granules plates were produced by injection molding with the dimensions 10 x 100 x 100 mm.

The light transmission in the visible range is 90% and the Haze 1.5%.

The material was laser-marked with a frequency-doubled Nd: YAG laser (emission wavelength 532 nm, power level 4, duration 1 min).

Comparative Example 4 Production of undoped polyamide plates

From Trogamid® CX 7323, a commercial product of Degussa AG, Business Unit High Performance Polymers, Marl, plates with the dimensions 10 x 100 x 100 mm were produced by injection molding.

The light transmission in the visible range is 90% and the Haze 1.5%.

The material was laser-marked with a frequency-doubled Nd: YAG laser (emission wavelength 532 nm, power level 4, duration 1 min).

Example 5: Results of the laser depth marking on PMMA compounds

The following images were prepared from internally engraved molded articles using a frequency-doubled Nd: YAG laser (emission wavelength 532 nm).

illustration 1 shows the result with the material of Example 1. In ITO-doped polymer material, a clear line pattern was produced.

Figure 2 shows the result with the undoped polymer material from Example 2. A line structure is difficult to recognize. The differences in the imaging accuracy are clearly visible.

Even when writing letters a significantly better imaging accuracy of the doped PMMA samples can be seen.

Figure 3 shows the result with the material from example 1. With the doped material every single point in the letter is clearly visible. All points are separated. A confluence of dots due to uncontrolled cracking is not observed.

Figure 4 shows the result with the undoped polymer material from Example 2. Here, the letter "a" is traversed by cracks and the edge appears very blurred.

In comparison to lead crystal glass, which is commonly used for the production of art objects by laser engraving, the superiority of the imaging accuracy of doped PMMA in laser engraving is clearly visible.

While at Figure 5 (Material of Example 1) the dot cloud pattern can be seen with high imaging accuracy, a very blurred line pattern is obtained in lead crystal glass. Figure 6 shows the result of the interior engraving in lead crystal glass (same point cloud file as in Figure 5 ).

The outstanding imaging accuracy of the doped PMMA is also observed in the third dimension.

Figure 7 shows the side view of the letter "S" Figure 5 (Material from Example 1). A line pattern of approximately 10 lines that are completely separated from each other can be observed.

Figure 8 shows the same picture structure in the lead crystal block. The approximately 10 lines are much wider and more offset than the lines in Figure 7 ,

Claims (15)

1. Plastic moulded bodies having two- or three-dimensional image structures produced in the interior through laser subsurface engraving, characterized in that the plastic moulded bodies consist of plastic materials including a content of nanoscale metal oxides having a particle size from 1 to 500 nm, wherein not only the plastic material but also the included metal oxide is transparent to the laser light used for producing the image structures.
2. Plastic moulded bodies according to Claim 1, characterized in that the particle size of the metal oxides included in the plastic material is 5 to 100 nm.
3. Plastic moulded bodies according to Claims 1 or 2, characterized in that the content of metal oxides is 0.0001% to 0.1% by weight, preferably 0.001% to 0.01% by weight, relative to the plastic material.
4. Plastic moulded bodies according to Claims 1 to 3, characterized in that doped indium oxide, doped tin oxide, doped zinc oxide, doped aluminium oxide or doped antimony oxide is included in the plastic material as nanoscale metal oxide.
5. Plastic moulded bodies according to Claim 4, characterized in that indium-tin oxide, antimony-tin oxide or doped indium- or antimony-tin oxides are included in the plastic material as nanoscale metal oxide.
6. Plastic moulded bodies according to Claim 5, characterized in that blue indium-tin oxide is included in the plastic material as nanoscale metal oxide.
7. Plastic moulded bodies according to Claims 1 to 6, characterized in that the plastic matrix is based on poly(meth)acrylate, polyamide, polyurethane, polyolefins, styrene polymers and styrene copolymers, polycarbonate, silicones, polyimides, polysulphone, polyether sulphone, polyketones, polyether ketones, polyphenylene sulphide, polyesters, polyethylene oxide, polyurethane, polyolefins and chlorinated or fluorinated polymers.
8. Plastic moulded bodies according to Claims 1 to 7, characterized in that the plastic matrix is based on polymethyl methacrylate.
9. Plastic moulded bodies according to Claims 1 to 7, characterized in that the plastic matrix is based on bisphenol A polycarbonate.
10. Plastic moulded bodies according to Claims 1 to 7, characterized in that the plastic matrix is based on polyamide.
11. Plastic moulded bodies according to Claims 1 to 7, characterized in that the plastic matrix is based on cyclo-olefinic copolymers made of norbornene and α-olefins.
12. Plastic moulded body according to Claims 1 to 11, characterized in that the plastic moulded body is transparent to laser light with a wavelength of 300 to 1300 nm.
13. Plastic moulded body according to Claim 12, characterized in that the plastic moulded body is transparent to laser light with a wavelength of 400 to 800 nm.
14. Plastic moulded body according to Claim 12, characterized in that the plastic moulded body is transparent to laser light with a wavelength of 800 to 1300 nm.
15. Process for producing two- or three-dimensional image structures in the interior of plastic moulded bodies through laser subsurface engraving, characterized in that moulded bodies consisting of plastic materials having a content of nanoscale metal oxides with particle size from 1 to 500 nm are imagingly irradiated with laser light to which not only the plastic material but also the included metal oxide is transparent.

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