Laser marked and laser welded moldings and their manufacture

Abstract

The present invention relates to a molded body comprising at least a first molded part and a second molded part, the first molded part being at least partially transparent to NIR radiation and the second molded part absorbing NIR radiation such that the first molded part and the second molded part are at least partially joined to one another by laser transmission welding, the first molded part having at least one partial area which is darkly colored and at least a part of the partial area has a lightly colored laser marking ... The molding material consists essentially of a molding material, which contains, based on the total weight of the molding material, A) more than 38.2% to 99.98% by weight of a thermoplastic polymer or a mixture of thermoplastic polymers, B) 0.01% to less than 0.8% by weight of titanium dioxide particles having an average primary particle size in the range of 0.5 nm to 25 nm, C) 0.01% to 1.0% by weight of one or more soluble dyes having absorption in the NIR range which enable partial transmission of NIR radiation of the first molded part, and D) 0 to 60% by weight of further additives. Furthermore, the present invention relates to a method for producing the molding as well as to the use of the molding material as a molded part having a laser marking portion in producing the molding.

Description

[Technical field]

[0001] The present invention relates to a molded body comprising at least a first molded part and a second molded part, the first molded part being at least partially transparent to NIR radiation and the second molded part absorbing NIR radiation such that the first molded part and the second molded part are at least partially joined to one another by laser transmission welding, the first molded part having at least one partial area which is darkly colored and at least a part of the partial area has a lightly colored laser marking ... The molding material consists essentially of a molding material, which contains, based on the total weight of the molding material, A) more than 38.2% to 99.98% by weight of a thermoplastic polymer or a mixture of thermoplastic polymers, B) 0.01% to less than 0.8% by weight of titanium dioxide particles having an average primary particle size in the range of 0.5 nm to 25 nm, C) 0.01% to 1.0% by weight of one or more soluble dyes having absorption in the NIR range which enable partial transmission of NIR radiation of the first molded part, and D) 0 to 60% by weight of further additives. Furthermore, the present invention relates to a method for producing the molding as well as to the use of the molding material as a molded part having a laser marking portion in producing the molding.

[0002] Plastic moldings, which are used, for example, as covers, electrical appliances, trims or exterior coatings in the automotive sector, are themselves often made up of different molded parts which must be permanently joined to one another.

[0003] There are many different methods for welding plastic molded parts (Kunststoffe 87, (1997), 11, 1632-1640). Laser welding or laser transmission welding is a method frequently used for permanently joining molded parts. The prerequisite for the use of laser transmission welding is that the radiation emitted by the laser first penetrates a first molded part that is sufficiently transparent to the laser light of the wavelength used and is then absorbed by the second molded part that is in contact with the first molded part, for example in a thin layer. The contact area melted in this way then solidifies, so that a permanent joining of the two adherends, i.e. the first and second molded parts, is possible. Usually, lasers that emit in the near IR (NIR) range are used here. The first molded part is therefore sometimes called a "NIR-transparent adherend" and the second molded part is sometimes called a "NIR-absorbing adherend".

[0004] Furthermore, there is the possibility of marking the molded parts by laser. In this case, for example, the adherends which also bring about the joining of the molded parts by laser welding can be marked. In this case, depending on the color of the molded parts, a contrasting appearance must be produced by the laser marking in order to produce a contrast. Often, the molded parts which bring about the welding are darkly colored in order to ensure the absorption of NIR radiation for the heat generation. In that case, light-colored characters must be produced by laser marking. Often, NIR laser radiation is also used for this purpose (for example, 1064 nm), but marking lasers working in the visible range (for example, 532 nm) or UV range (for example, 355 nm) are also widespread.

[0005] However, when the "NIR-transparent" adherend is darkly pigmented and nevertheless has a (light-colored) laser marking on the one hand and is welded to a further adherend on the other hand, no satisfactory solution is disclosed in the prior art.

[0006] WO 2020 / 118059 A1 describes a polyester molding material which comprises two soluble anthraquinone dyes as well as titanium dioxide. The problem of the patent is to provide a molding material with which packaging for photosensitive articles can be produced. The aim is that even with a small wall thickness (0.5 mm) the light transmission in the UV-VIS range (190-750 nm) is as low as possible (<1%). In the NIR range at 850 nm, still very low transmission values ​​(2.5%) are found. The primary particle size of the titanium dioxide is not mentioned. The use of the molding material as a component transparent to the NIR in laser transmission welding processes is not disclosed, nor is the laser markability mentioned in the patent.

[0007] CN107163515 A describes lightly colored or colorless polyester molding materials that can be joined to one another by laser transmission welding. The absorbing adherends then contain NIR absorbers with a slight inherent color. NIR-transparent adherends should be provided with increased NIR transparency. The increase in NIR transparency is achieved by the addition of surface-modified titanium dioxide and / or zinc oxide particles and with low molecular weight alcohols. The oxide particles then have a size of 30-400 nm. Laser markability is not described in this patent.

[0008] WO 2006 / 042623 A1 describes a molding material that is transparent to NIR, which may be added with "laser scattering absorber" or "laser scattering additive". Laser scattering additives include TiO2, CaCO3, MgCO3 and glass beads. In the examples, the addition of laser scattering absorber leads to increased absorption in the transparent adherend, which is accompanied by a lower transmittance.

[0009] WO 2009 / 066232 A1 describes NIR-absorbing molding materials that can be used in laser welding processes. Various pigments, especially TiO2 pigments with an average particle size of 30 nm to 4.35 μm, are used to reduce the NIR transmission of plastics. Laser-transparent molding materials are not specifically described.

[0010] There is therefore a demand for mouldings, NIR-transparent moulded parts and moulding materials for such NIR-transparent moulded parts and corresponding methods, in which the "NIR-transparent" adherend is darkly pigmented and can nevertheless have laser markings on the one hand and can be welded to further adherends on the other hand.

[0011] It is therefore an object of the present invention to provide such a moulded body, a moulded part which is transparent in the NIR and a moulding material for such a moulded part which is transparent in the NIR.

[0012] The problem is to provide a molded body comprising at least a first molded part and a second molded part, the first molded part being at least partially transparent to NIR radiation and the second molded part absorbing NIR radiation such that the first molded part and the second molded part are at least partially joined to one another by laser transmission welding, the first molded part having at least one partial region which is darkly colored and at least a part of the partial region has a lightly colored laser marking, the first molded part at least partially consisting of a molding material which, based on the total weight of the molding material, respectively: A) more than 38.2% by weight to 99.98% by weight of a thermoplastic polymer or a mixture of thermoplastic polymers; B) 0.01% to less than 0.8% by weight of titanium dioxide particles having an average primary particle size in the range of 0.5 nm to 25 nm; C) 0.01% to 1.0% by weight of one or more soluble dyes having absorption in the NIR range that allow partial transmission of NIR radiation through the first molded part, and D) Further additives 0-60% by weight The problem is solved by a molded body comprising:

[0013] The problem is, a) joining the first molded part with the second molded part by laser transmission welding in the NIR range; b) marking the first molded part, in particular by laser marking in the UV / VIS range, where step b) is carried out before or after step a), preferably after step a); The problem is further solved by a method for producing a shaped body according to the present invention, which comprises:

[0014] The object is further achieved by the use of the molding materials described herein as laser-marked molded parts in the production of moldings.

[0015] It has surprisingly been found that by using a molding material containing titanium dioxide particles of a particular primary particle size and a soluble dye, it is possible to provide a deeply pigmented, laser markable and weldable NIR transparent adherend.

[0016] The molded body according to the present invention comprises at least a first molded part and a second molded part. The molded body itself can take a wide variety of forms and can be used in a correspondingly wide variety of ways. The molded body can essentially extend in one dimension, as is the case with filaments. An essentially two-dimensional extension is also possible, as is the case with films. However, typically, the molded body is a three-dimensional object, in particular a component that can be used as a cover, an electrical device, trim or outer coating, for example in the automotive field.

[0017] The molded body according to the invention may consist exclusively of the two (first and second) molded parts (adherends) or may have further molded parts, depending in particular on the intended use.

[0018] The first and second adherends are joined to one another, the bond being produced by means of a laser transmission welding method. The two adherends do not have to be completely welded to one another. Accordingly, it is sufficient that they are only partially welded. The welded area can be point-like (weld point), linear (weld seam) or two-dimensional (weld surface).

[0019] The laser transmission welding (also called laser beam welding or simply laser welding) is known in the prior art. In the case of the laser transmission welding, in particular laser light in the NIR range is used. The basic principles of laser transmission welding are described in the technical literature (see, for example, Kunststoffe 87, (1997) 3, 348-350; Kunststoffe 88, (1998), 2, 210-212; Kunststoffe 87 (1997) 11, 1632-1640; Plastverarbeiter 50 (1999) 4, 18-19; Plastverarbeiter 46 (1995) 9, 42-46).

[0020] A prerequisite for the use of laser beam welding is that the radiation emitted by the laser first passes through a molded part that is sufficiently transparent to the laser light of the NIR wavelength used (also called NIR-transparent molded part). Preferably, the wavelength is in the range of 800 nm to 1200 nm.

[0021] Sufficient transparency is given when the first molded part is at least partially transparent to NIR radiation. This causes the NIR radiation to impinge on the second molded part to a sufficient extent to allow laser welding. Preferably, the first molded part at least partially has a transmission of at least 10% to NIR radiation. In this case, "at least partially" means that the stated transmission is obtained at least in the area corresponding to the welding area. Outside this welding area, the stated transmission of at least 10% is not necessary. However, preferably, the entire first molded part has a transmission of at least 10%.

[0022] The NIR radiation transmitted through the first molded part finally strikes the weld area where it is absorbed in a thin layer of the second molded part in contact with the NIR transparent molded part (NIR absorbing molded part). In the thin layer that absorbs the NIR laser light, the laser energy is converted to heat, which leads to melting in the weld area and ultimately bonding of the NIR transparent molded part and the NIR absorbing molded part.

[0023] For the laser transmission welding, lasers in the wavelength range of 800-1200 nm are usually used. Within the wavelength range of lasers used for the thermoplastic welding, Nd:YAG-lasers (1064 nm) or high-power diode lasers (800-1000 nm) are common.

[0024] Several laser welding variants are available, all based on the transmission principle. For example, contour welding is a sequential welding method, whereby either the laser beam is guided along a freely programmable seam contour or the components are moved relative to a fixedly installed laser. In simultaneous welding, the linearly emitted radiation of individual high-power diodes is positioned along the seam contour to be welded. Thus, melting and welding of the entire contour takes place simultaneously. Quasi-simultaneous welding is a combination of contour welding and simultaneous welding. The laser beam is guided along the weld seam contour at very high speeds of more than 10 m / s using a galvanometer mirror (scanner). Due to said high speeds, the joining area is gradually heated and melted. Compared to simultaneous welding, there is a high flexibility in changing the weld seam contour. Mask welding is a method in which a linear laser beam is moved across the parts to be joined. By means of a mask, the radiation is intentionally blocked and impinges on the joining surface only at the places to be welded. The method allows the production of very accurately positioned weld seams. These methods are known to the person skilled in the art and are described, for example, in "Handbuch Kunststoff-Verbindungstechnik" (GW Ehrenstein, Hanser, ISBN 3-446-22668-0) and / or in the DVS-Richtlinie 2243 "Laserstrahlschweissen thermoplastischer Kunststoffe".

[0025] Even if the NIR transparency of the different thermoplastics may differ as a result, conventional thermoplastics have a sufficiently high transparency in the NIR range that a laser welding process can be carried out if suitable process parameters are selected (thickness of the NIR-transparent adherend, intensity of the laser beam, speed of the welding method, etc.).

[0026] Due to the low NIR absorption of the thermoplastics, the laser-absorbing adherend is usually equipped with an NIR-absorbing additive. Pigments that have as high an absorption as possible in the wavelength range of the welding laser are particularly suitable for this purpose. Particularly suitable and widespread is the use of all kinds of carbon black as NIR-absorbing pigments. Therefore, the NIR-absorbing adherend is often colored dark to black.

[0027] If the NIR-transparent adherend has a similar color to the NIR-absorbing adherend, care must be taken that the coloring of the NIR-transparent adherend is carried out especially in the wavelength range perceptible by the human eye (approximately 380-750 nm) and that the NIR transmittance is as little impaired as possible.

[0028] For the coloring of plastics, two types of colorants are available in principle: pigments and soluble dyes (some simply referred to as "dyes"). The coloring of the above-mentioned NIR-transparent substrates with pigments is not the subject of the present invention, since conventional pigments have an average particle size in the range of 0.5 to 4 μm, which scatters NIR light and thus reduces the NIR transmittance and is disadvantageous for the laser welding process. Carbon blacks have a particularly adverse effect on the NIR transmittance, since even in very small amounts they significantly reduce the NIR transmittance by absorption.

[0029] Scattering of NIR light in colorants can be largely avoided when soluble dyes are used, since they can be distributed in the thermoplastic to the extent that they are molecularly dispersed, and therefore are not a scattering source for NIR light. Furthermore, the NIR absorption of the soluble dyes should be as low as possible.

[0030] Within the scope of the present invention, the molded body according to the invention has at least the first molded part and the second molded part. As already explained above, the first molded part is at least partially transparent to NIR radiation in order to enable laser welding. The second molded part absorbs NIR radiation so that the first molded part and the second molded part are at least partially joined to each other by laser transmission welding. The required absorption capacity for NIR radiation can be achieved, for example, by adding pigments, for example carbon black.

[0031] The first molded part furthermore has at least one part region which is darkly colored and at least a part of the part region has a lightly colored laser marking. Here, the terms "dark" and "light" mean that the laser marking can be distinguished from the part region of the first molded part which has the marking, and which is lighter in color. The first molded part does not have to be completely darkly colored, only the part region which has the marking is sufficient. This part region is usually not completely covered by the letter, but is occupied by a part of the part region. It is self-evident within the scope of the present invention that the darkly colored part region is selected in such a way that it is permeable by NIR radiation to enable the laser welding and on the other hand is available for laser marking.

[0032] It is not necessary, but preferred, that the entire first moulded part is darkly coloured. Preferably, the partial area of ​​the first moulded part having a light-coloured laser marking has a light intensity of at most 50 cd / m 2 , preferably at most 30 cd / m 2 More preferably, the contrast value between the background luminance of a partial region of the first molded part having a light-colored laser-marked portion and the luminance of the laser-marked portion is at least 80%.

[0033] Within the scope of the present invention, the term "laser marking" does not mean marking with characters in the narrower sense, but rather refers to the use of signs in a wide variety of ways, such as letters, numbers, special characters, bar codes and QR codes, pictograms, etc.

[0034] Methods for laser marking of plastic moldings are known in the prior art. The laser marking is a fast and contactless method for providing an optically recognizable marking on a plastic part. This may be a human-readable or machine-readable marking. Machine-readable markings are, for example, bar codes, QR codes or data matrix codes. Such codes are often used to include important information characterizing the marked plastic part (e.g. manufacturer, date of manufacture, model number, batch number, etc.). In modern production processes, the mechanical reading of such codes must be reliable and successful, for which there are standardized test methods for assessing the quality of codes (e.g. ISO IEC 15 / TR29158). An important criterion is then the contrast (brightness difference) between the marking and the background. Depending on the coloring of the plastic, two marking cases can be distinguished in which high contrast values ​​can be achieved: 1. Plastic color = light color and text color = dark color (i.e. color change from light to dark by laser) 2. Plastic color = dark and text color = light (i.e. color change from dark to light by laser).

[0035] The colour change from light to dark (not within the scope of the present invention) can be achieved for example by carbonisation, and from dark to light by decolourisation or foaming, for example. The underlying mechanisms are described in the technical literature, for example in Kunststoffe 2006 / 10 p.199 - 203, Kunststoffe 2009 / 06 p.66 - 69 or Journal of Materials Processing Technology 1994 / 42 p.95 - 133.

[0036] Commercially available marking devices work with laser light from the UV to the IR range. The most widespread are Nd:YAG and Nd:YVO4 lasers and marking wavelengths of 1064, 532 and 355 nm.

[0037] Within the scope of the present invention, it is preferred if laser radiation in the UV / VIS range (<800 nm, preferably 100 nm to 780 nm, in particular in the UV range from 100 nm to 380 nm) is used for the laser marking.

[0038] In order to be able to achieve good marking contrast and homogeneous, finely resolved markings, the plastics to be marked must at least partially absorb the light of the laser. Since a great many plastics barely absorb light in the range of the wavelengths described, they must be mixed with additives that take over these functions. In the visible range, these can be colorants, whereas absorbers for the UV and NIR range can appear colorless. It has often proven to be advantageous if the absorbers are of pigment type and are not present in the plastic in dissolved form (unlike the soluble dyes mentioned above). All kinds of carbon black are such pigment-type absorbers and are suitable for the entire UV to NIR range.

[0039] When two plastic moldings are joined together by laser transmission welding, one of the adherends is NIR-absorbing, as described above.Therefore, in principle, it is easily possible to apply laser markings to the NIR-absorbing adherend, for example with a 1064 nm marking laser.Due to lack of space or unfavorable geometrical shape of the components, it is advantageous not to apply the laser markings to the NIR-absorbing adherend.Then, as within the scope of the present invention, it may be necessary to apply the laser markings to an adherend that is transparent to NIR.

[0040] The first molded part is at least partially made of a molding material, the molding material each comprising, based on the total weight of the molding material: A) more than 38.2% by weight to 99.98% by weight of a thermoplastic polymer or a mixture of thermoplastic polymers; B) 0.01% to less than 0.8% by weight of titanium dioxide particles having an average primary particle size in the range of 0.5 nm to 25 nm; C) 0.01% to 1.0% by weight of one or more soluble dyes having absorption in the NIR range that allow partial transmission of NIR radiation through the first molded part, and D) Further additives 0-60% by weight Contains:

[0041] Advantageously, the first molded part is formed exclusively from the molding material. It contains the components A) to D). Preferably, it consists of these components. In this case, the component D) is not included as an essential component (0%), and preferably, the component D) is included, for example, in an amount of at least 0.01% by weight based on the total weight of the molding material. Preferably, the molding material contains 43.8% to 89.96% by weight of A), 0.02% to 0.65% by weight of B, 0.02% to 0.55% by weight of C, and 10% to 55% by weight of D, based on the total weight of the molding material. More preferably, the molding material contains 44.1% by weight to 89.9% by weight of A, 0.05% by weight to 0.35% by weight of B, 0.05% by weight to 0.55% by weight of C, and 10% by weight to 55% by weight of D, based on the total weight of the molding material.

[0042] As component A), the molding material comprises a thermoplastic polymer or a mixture of thermoplastic polymers. Suitable thermoplastic polymers are, for example, polyethene (PE), polypropene (PP), polystyrene (PS), styrene copolymers (SAN, ASA), polyvinyl chloride (PVC), polyamide (PA), polyester (PES), polycarbonate (PC), polyphenylene sulfide (PPS) and polyacrylate. Mixtures of two or more of these polymers of one type (e.g. two different PE polymers) or different types (e.g. one PE and one PP) can also be used.

[0043] polyester Preference is given to the following polyesters and also to mixtures thereof (names according to DIN EN ISO 1043-1): Polybutylene terephthalate (PBT) Polyethylene terephthalate (PET) Polytrimethylene terephthalate (PTT) Polycyclohexylene dimethylene terephthalate (PCT) Polyethylene naphthalate (PEN) Polybutylene Naphthalate (PBN) Polybutylene succinate (PBS) Polybutylene succinate adipate (PBSA) Polycyclohexylenedimethylenecyclohexanedicarboxylate (PCCE) Polyethylene succinate (PES) Polyhydroxyalkanoates (PHAs) Poly(3-hydroxybutyrate) (PHB) Polycaprolactone (PCL).

[0044] In addition to the structural units named above, small amounts of further structural units may also occur in the respective polymers, which may be derived from other diols and / or dicarboxylic acids.

[0045] Further examples of diols are: 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol and neopentyl glycol or mixtures thereof.

[0046] Further examples of dicarboxylic acids are: Terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,5-furandicarboxylic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid and cyclohexanedicarboxylic acid.

[0047] Preferably, the proportion of further monomers, based on the respective main component, is less than 20 mol %, particularly preferably less than 10 mol %.

[0048] In addition to (predominantly) homopolymers which may be derived primarily from dicarboxylic acids and diols, copolymers in which structural units occur in greater amounts which may be derived from several diols and / or dicarboxylic acids are also preferred.

[0049] Particularly preferred are polybutylene terephthalate (PBT) and polyethylene terephthalate (PET), and mixtures thereof.

[0050] PBT can be produced from 1,4-butanediol (BDO) and terephthalic acid by polycondensation, in which water is formed in addition to PBT. The polycondensation is usually started with an excess of BDO. The excess BDO is then separated off together with the water, so that BDO and terephthalic acid are finally again present in the PBT in a molar ratio of approximately 1:1. By selecting the process conditions, the average molar mass and the ratio of alcohol end groups and acid end groups can be adjusted as required.

[0051] Most commercially available PBT polymers contain more alcohol end groups than acid end groups. Preferred are polyesters with an acid end group content of less than 100 mmol / kg, preferably less than 50 mmol / kg and especially less than 40 mmol / kg.

[0052] The progress of the polycondensation reaction is usually accelerated by the addition of a catalyst. Conventional catalysts are alkyl orthotitanates. These catalysts remain in the polymer, mostly in part hydrolyzed form. Therefore, in commercial PBT polymers, titanium contents of 20 to 200 ppm can usually be detected by analysis. Residual titanium contents of less than 150 ppm are preferred. Residues of titanium-based catalysts are not active in the sense of the present invention.

[0053] The preparation of PBT from BDO and dimethyl terephthalate (DMT) can be carried out similarly, with methanol being formed instead of water as the condensation product other than PBT.

[0054] The viscosity number of the PBT is generally 50 to 220 cm 3 / g, preferably 80 to 160 cm 3 / g (measured at 25° C. in a 0.5% by weight solution in a phenol / o-dichlorobenzene mixture (1:1 by weight) according to ISO 1628).

[0055] The production of PET can be carried out similarly from ethylene glycol and terephthalic acid or DMT. An important side reaction in the production of PET is the condensation of ethylene glycol to diethylene glycol, which is again a diol compound that can be incorporated into the polymer chain. Commercially available PET therefore mostly contains a small proportion (<5 mol%) of diethylene glycol comonomer. However, if necessary, further comonomers are also added during the production of PET in order to adapt its melting and solidification behavior to the requirements of the respective processing method or use case. Examples of comonomers are diethylene glycol, isophthalic acid and 1,4-cyclohexanedimethanol.

[0056] An introduction to polyester production is given, for example, in “Kunststoff Handbuch 3 / 1 - Polycarbonate, Polyacetale, Polyester, Celluloseester”, edited by L. Bottenbruch, Carl Hanser Verlag 1992, p. 12 ff. An overview of PET polymers is given, for example, in the market study “Polyethylene Terephthalate, PERP 2017-2” by Nexant.

[0057] polyamide Semicrystalline or amorphous resins having a molecular weight (weight average) of at least 5,000, such as those described in U.S. Pat. Nos. 2,071,250, 2,071,251, 2,130,523, 2,130,948, 2,241,322, 2,312,966, 2,512,606 and 3,393,210, are preferred.

[0058] Examples of these are polyamides derived from lactams having 7 to 13 ring members, such as polycaprolactam, polycapryllactam and polylaurolactam, and also polyamides obtained by reaction of dicarboxylic acids with diamines.

[0059] As dicarboxylic acids, alkanedicarboxylic acids and aromatic dicarboxylic acids having 6 to 12, in particular 6 to 10, carbon atoms can be used. The acids which may be mentioned here are simply adipic acid, azelaic acid, sebacic acid, dodecanedioic acid and terephthalic acid and / or isophthalic acid.

[0060] Particularly suitable diamines are alkanediamines having 6 to 12, in particular 6 to 8, carbon atoms, as well as m-xylylenediamine, di-(4-aminophenyl)methane, di-(4-aminocyclohexyl)methane, 2,2-di-(4-aminophenyl)propane, 2,2-di-(4-aminocyclohexyl)propane or 1,5-diamino-2-methylpentane.

[0061] Preferred polyamides are polyhexamethylene adipamide, polyhexamethylene sebacamide and polycaprolactam and in particular copolyamide 6 / 66 (for example Ultramid® C31 from BASF SE), which has a proportion of caprolactam units of 5 to 95% by weight.Further suitable polyamides can be obtained from ω-aminoalkylnitriles, such as aminocapronitrile (PA 6) and adipic dinitrile with hexamethylenediamine (PA 66), by so-called direct polymerization in the presence of water, as described, for example, in DE-A 10313681, EP-A 1 198491 and EP 922065.

[0062] Furthermore, further mention may be made of polyamides obtainable, for example, by condensation of 1,4-diaminobutane with adipic acid at elevated temperatures (polyamide 4,6). Methods for the preparation of polyamides of this structure are described, for example, in EP-A 38 094, EP-A 38 582 and EP-A 39 524.

[0063] Furthermore, polyamides obtainable by copolymerization of two or more of the abovementioned monomers or mixtures of several polyamides, in any mixing ratio, are suitable, particularly preferably mixtures of polyamide 66 with other polyamides, in particular copolyamide 6 / 66.

[0064] Furthermore, semi-aromatic copolyamides, such as PA 6 / 6T and PA 66 / 6T, which have a triamine content of less than 0.5% by weight, preferably less than 0.3% by weight, have proven to be particularly advantageous (see EP-A 299 444). Further high-temperature resistant polyamides are known from EP-A 19 94 075 (PA 6T / 6I / MXD6).

[0065] The preparation of the preferred partially aromatic copolyamides having a low triamine content can be carried out according to the methods described in EP-A 129 195 and EP-A 129 196.

[0066] The following non-exhaustive list includes further polyamides A) which are mentioned in the sense of the present invention and the monomers which they contain.

[0067] AB-Polymer: PA 4 Pyrrolidone PA 6 ε-caprolactam PA 7 Enantholactam PA 8 Caprylactam PA 9 9-Aminopelargonic Acid PA 11 11-aminoundecanoic acid PA 12 Laurolactam AA / BB-Polymer PA 46 Tetramethylenediamine, Adipic Acid PA 66 Hexamethylenediamine, Adipic Acid PA 69 Hexamethylenediamine, Azelaic Acid PA 610 Hexamethylenediamine, Sebacic acid PA 612 Hexamethylenediamine, Decanedicarboxylic acid PA 613 Hexamethylenediamine, undecanedicarboxylic acid PA 1212 1,12-Dodecanediamine, decanedicarboxylic acid PA 1313 1,13-Diaminotridecane, undecanedicarboxylic acid A PA 6T Hexamethylenediamine, Terephthalic acid PA 9T 1,9-Nonanediamine, terephthalic acid PA MXD6 m-Xylylenediamine, Adipic Acid PA 6I Hexamethylenediamine, Isophthalic acid PA 6-3-T Trimethylhexamethylenediamine, terephthalic acid PA 6 / 6T (see PA 6 and PA 6T) PA 6 / 66 (see PA 6 and PA 66) PA 6 / 12 (see PA 6 and PA 12) PA 66 / 6 / 610 (see PA 66, PA 6 and PA 610) PA 6I / 6T (see PA 6I and PA 6T) PA PACM 12 Diaminodicyclohexylmethane, Laurolactam PA 6I / 6T / PACM e.g. PA 6I / 6T + diaminodicyclohexylmethane PA 12 / MACMI Laurolactam, Dimethyldiaminodicyclohexylmethane, Isophthalic Acid PA 12 / MACMT Laurolactam, Dimethyldiaminodicyclohexylmethane, Terephthalic Acid PA PDA-T Phenylenediamine, Terephthalic Acid.

[0068] Commercially available polymers of any kind are usually provided with a specific viscosity. Mixing of polymers differing essentially only in their viscosity can always be carried out, for example where the "average" viscosity is adjusted.

[0069] Preferably, the thermoplastic polymer is a polyester or polyamide, more preferably a polyester, or a mixture of several of these thermoplastic polymers. A preferred ester is polybutylene terephthalate (PBT). Accordingly, in a preferred embodiment of the present invention, the thermoplastic polymer is PBT or a mixture of thermoplastic polymers comprising at least 45% by weight, preferably at least 60% by weight, of PBT, based on the total weight of A).

[0070] Preferably, the second moulded part also comprises one of the above mentioned thermoplastics or a mixture thereof.

[0071] As component B), the molding material contains titanium dioxide particles having an average primary particle size in the range of 0.5 nm to 25 nm. Preferably, the titanium dioxide particles have an average primary particle size in the range of 5 nm to 25 nm, more preferably in the range of 10 nm to 25 nm. The determination of the average particle size can be carried out, for example, in accordance with DIN ISO 9276-2 (2018-09). The titanium dioxide particles can be coated or uncoated.

[0072] As component C), the molding material comprises one or more soluble dyes with absorption in the NIR range which allow partial transmission of NIR radiation by the first molded part. Suitable dyes are known to the person skilled in the art and may, for example, be of the pyrazolone, perinone, anthraquinone, methine, azo, anthrapyridone or coumarin type and are described, for example, in WO 02 / 057353 (WO 02057353), EP 1258506 A1 (EP 1258506), EP 1353986 A1 (EP 1353986), EP 1353991 A1 (EP 1353991), EP 1582565 A1 (EP 1582565), EP 1797145 A1 (EP 1797145), EP 1847375 A1 (EP 3421540 ... No. 3,421,540, JP 4176986 or JP 4073202.

[0073] The term "soluble" is to be understood within the scope of the present invention as meaning that the dye in the molding material may be soluble in its liquid phase, so that a molecularly dispersed distribution is possible. Soluble dyes may therefore be pyrazolone, perinone, anthraquinone, methine, azo, anthrapyridone or coumarin dyes.

[0074] Exemplary soluble dyes that are commercially available are listed under the Color Index category "Solvent." Examples are anthraquinone dyes, such as CI Solvent Green 3, or perinone dyes, such as CI Solvent Red 179.

[0075] If the NIR transparent substrate maintains a black or dark grey coloration, it is also possible to combine two or more chromatic soluble dyes such that the absorption of the dye mixture spans the entire visible region.

[0076] Furthermore, the molding material may contain additives. These depend on the field of application of the molding. Exemplary additives (additives) are flame retardants, such as phosphorus compounds, organic halogen compounds, nitrogen compounds and / or magnesium hydroxide, stabilizers, processing aids, such as lubricants / mold release agents, nucleating agents, hydrolysis stabilizers, impact modifiers, such as rubber or polyolefins, etc., provided that they do not have too strong an absorption in the region of the wavelength of the welding laser used.

[0077] As fibrous reinforcing materials other than glass fibers, aramid fibers, mineral fibers and whiskers are worthy of consideration.Suitable mineral fillers include, by way of example, calcium carbonate, dolomite, calcium sulfate, mica, fluoromica, wollastonite, talc and kaolin.Glass beads (solid or hollow) can be used as well.To improve mechanical properties, the fibrous reinforcing materials and the mineral fillers can be surface-treated.

[0078] Preferably, the molding material contains glass fiber as component D. The proportion of the glass fiber is preferably 10% by weight to 50% by weight based on the total weight of the molding material.

[0079] A hydrolysis stabilizer may be contained in the molding material, the suitable ratio being 1% by weight to 5% by weight based on the total weight of the molding material.

[0080] A suitable hydrolysis stabilizer is epoxidized vegetable oil. More suitable vegetable oils have a high proportion of monounsaturated and / or polyunsaturated fatty acids, since then a high specific epoxide content can be achieved. Derivatives of such vegetable oils, which can be obtained by transesterification with other monohydric or polyhydric alcohols, can also be epoxidized and can also be used as hydrolysis stabilizers. Examples are epoxidized linseed oil, epoxidized soybean oil or epoxidized fatty acid methyl esters based on linseed oil or soybean oil. Such compounds are produced on an industrial scale and used as plasticizers for PVC or as raw materials for paints and polymers. A review of industrially important epoxides and their manufacturers can be found, for example, in "IHS Chemical Process Economics Program, Report 62B, 2014, Eco-Friendly Plasticizers".

[0081] Further suitable hydrolysis stabilizers are epoxy resins having terminal epoxy groups, which are prepared from bisphenol A and epichlorohydrin, and are used as raw materials for paints and coatings, and may have an average molecular weight of several hundred to several thousand g / mol.

[0082] Further suitable hydrolysis stabilizers are monomeric, oligomeric or polymeric carbodiimides.

[0083] A further subject of the invention is a method for producing a shaped body according to the invention, comprising the steps of: a) joining the first molded part with the second molded part by laser transmission welding in the NIR range; b) marking the first molded part by laser marking, preferably in the UV / VIS range, where step b) is carried out before or after step a), preferably after step a); Includes.

[0084] The joining by a laser transmission process in step a) as well as the laser marking in step b) are explained in more detail above and are well known to the person skilled in the art.

[0085] Likewise, a further subject of the invention is the use of such molding materials as described above as laser-marked molding parts in the production of moldings, in particular moldings according to the invention. EXAMPLES

[0086] raw material PBT Polymer: A) Ultradur (登録商標) B2550 natur. This product has the following properties: Viscosity number (according to ISO 1628, in phenol / 1,2-dichlorobenzene (1:1), 25°C): 108 cm 3 / g Acid end groups (by alkaline titration): 22mmol / kg Titanium content (by X-ray fluorescence measurement): 102 ppm.

[0087] Glass fiber: B) 3B DS 3185 E-10N: Glass fiber of E-glass, average diameter about 10 μm, with sizing for polyester. Glass fiber sizing is usually a complex formulation and includes treatment with silane, film formers and further additives. Detailed examples can be found, for example, in EP 2 540 683 A1, EP 2 554 594 A1 or EP 1993 966 B1. Academic literature on this can be found, for example, in "Glass Fibre Sizings" by JL Thomason (ISBN 978-0-9573814-1-4).

[0088] Release agent: C) Loxiol P 861 / 3.5 from Emery Oleochemicals: fatty acid esters with pentaerythritol.

[0089] Hydrolytic stabilizer: D1) Vikoflex 7190 from Arkema: Epoxidized linseed oil, approximately 9.5% by weight of oxirane oxygen D2) ARALDITE GT 7077 from Jana: An epoxy resin based on bisphenol A and epichlorohydrin, with approximately 1% by weight oxirane oxygen.

[0090] Dyes (color index type "solvent"): E1) CI Solvent Green 3, e.g. Macrolex Gruen 5B from RheinChemie E2) CI Solvent Red 179, e.g. Macrolex Rot E2G from RheinChemie.

[0091] Titanium dioxide pigment: F1) Hombitec RM 230 L (from Venator), ultrafine TiO2 particles with inorganic (Al and Ce based) and organic (stearic acid) surface treatment. Average primary particle size about 20 nm. F2) Hombitec RM 130 F (from Venator), ultrafine TiO2 particles with inorganic (Al-based) and organic (stearic acid) surface treatment. Average primary particle size about 15 nm. F3) TiO2 F-RC5 (from Venator), TiO2 particles with inorganic (Al-based) and organic surface treatment (silicone etc.). Average primary particle size about 190 nm. F4) Kronos 2220 (from Kronos), TiO2 particles with inorganic (Al and Si based) and organic surface treatment (silicone). Primary particle size approx. 300-400 nm.

[0092] test Tensile test on specimen type 1A according to ISO 527 UV-VIS-NIR transmittance: 2 mm thick injection molded plates were measured with a laboratory photometer equipped with an Ulbricht bulb.

[0093] Laser marking: An injection-molded plate with a thickness of 2 mm was marked with a commercial marking device (Trumpf TruMark 6330, Nd:YVO4 laser, 355 nm wavelength). The operating current intensity of the laser beam and the scanner frequency were varied in order to obtain the optimum marking result (maximum contrast value). The optimum marking result was adopted for the luminance measurement.

[0094] Luminance Measurement: The brightness of the laser marked surface and background was measured using a Minolta Luminance Meter LS-110. From the brightness values, the contrast values ​​were calculated according to the following formula: 1) Light background / dark marking: Contrast = 100% x (background brightness - marking brightness) / background brightness 2) Dark background / light marking: Contrast = 100% x (marking brightness - background brightness) / marking brightness.

[0095] Hydrolytic aging of tensile specimens in superheated steam for 7 days at 110° C. The specimens were used for tensile testing without prior drying (only for compositions with hydrolytic stabilizer).

[0096] Compound manufacturing All compounds were produced using a twin-screw extruder (shaft diameter 25 mm). The following process parameters were selected: speed 200 rpm, throughput 14 kg / h, temperature 270° C. The glass fibres and Vikoflex 7910 were metered directly into the melt, all other raw materials (PBT and further additives) were metered in via a feed throat.

[0097] result Table 1 [Table 1]

[0098] The compositions A to D show that only sufficiently small titanium dioxide particles bring about the desired improvement: when the particles are too large (C and D), the tensile strength is clearly reduced, the transmittance values ​​in the NIR range drop, and the contrast values ​​increase to a lesser extent than from A to B.

[0099] Table 2 [Table 2]

[0100] The compositions E to L show that already small amounts of suitably small titanium dioxide particles bring about the desired improvement in contrast values, without essentially impairing the transmittance values ​​in the NIR region. However, it is also observed that the titanium dioxide reduces the effectiveness of the hydrolysis stabilizer. Particularly noticeable is this effect at a titanium dioxide proportion of 0.8% (not according to the invention).

[0101] Table 3 [Table 3]

[0102] Compositions M to N show that with appropriately small titanium dioxide particles the contrast value in the uncolored product can also be improved, however the contrast value nevertheless remains low and unsatisfactory.

Claims

1. A molded body comprising at least a first molded part and a second molded part, the first molded part being at least partially transparent to NIR radiation and the second molded part absorbing NIR radiation such that the first molded part and the second molded part are at least partially joined to one another by laser transmission welding, the first molded part having at least one partial region which is darkly colored and at least a part of the partial region has a lightly colored laser marking, the first molded part at least partially consisting of a molding material, the molding material being, based on the total weight of the molding material, A) from more than 38.2% to 99.98% by weight of a thermoplastic polymer or a mixture of thermoplastic polymers; B) 0.01% to less than 0.8% by weight of titanium dioxide particles having an average primary particle size in the range of 0.5 nm to 25 nm; C) 0.01% to 1.0% by weight of one or more soluble dyes having absorption in the NIR range that allow partial transmission of NIR radiation through the first molded part; and D) Further additives 0-60% by weight The molded body comprising:

2. The molding material contains 43.8% by weight to 89.96% by weight of A), 0.02% by weight to 0.65% by weight of B, 0.02% by weight to 0.55% by weight of C, and 10% by weight to 55% by weight of D. The molded body according to claim 1.

3. The molding material contains 44.1% by weight to 89.9% by weight of A), 0.05% by weight to 0.35% by weight of B, 0.05% by weight to 0.55% by weight of C, and 10% by weight to 55% by weight of D. The molded body according to claim 1.

4. 4. Moulded body according to claim 1, characterized in that the thermoplastic polymer is a polyester or a polyamide, preferably a polyester, or a mixture of several of these thermoplastic polymers.

5. 4. The molding according to claim 1, wherein the thermoplastic polymer is PBT or a mixture of thermoplastic polymers having at least 45% by weight of PBT, based on the total weight of A).

6. 4. Moulded body according to claim 1, characterized in that the titanium dioxide particles have an average primary particle size in the range of 5 nm to 25 nm, preferably 10 nm to 25 nm.

7. The molding according to any one of claims 1 to 3, characterized in that as additive D, 10 wt% to 50 wt% of glass fibers are contained, based on the total weight of the molding material.

8. 4. The molding according to claim 1, further comprising as additive D 1% by weight to 5% by weight of a hydrolysis stabilizer, based on the total weight of the molding material.

9. The partial area of ​​the first molded part having a light-colored laser marking has a brightness of at most 50 cd / m ２ , preferably at most 30 cd / m ２ 4. The molded body according to claim 1, wherein the molded body has a background brightness of 0.1 to 0.5 nm.

10. The molded article according to any one of claims 1 to 3, characterized in that the contrast value between the background luminance of the partial region of the first molded part having a light-colored laser-marked portion and the luminance of the laser-marked portion is at least 80%.

11. 4. The molding according to claim 1, wherein the NIR radiation is in the wavelength range from 800 nm to 1200 nm.

12. 4. The molding according to claim 1, wherein the first molded part at least partially has a transmittance for NIR radiation of at least 10%.

13. A method for producing the molded body according to any one of claims 1 to 3, comprising the steps of: a) joining the first molded part with the second molded part by laser transmission welding in the NIR range; b) marking the first molded part by laser marking, where step b) is carried out before or after step a), preferably after step a); The method comprising:

14. 14. The method according to claim 13, characterized in that the laser marking is carried out with laser light in the UV / VIS range.

15. 4. Use of a molding material as claimed in claim 1 as a laser-marked molded part in the production of moldings.