DE102011007196A1 - Producing a composite part contains joint partner including molded part made of a polyamide molding composition and a molded part made of a methacrylate copolymer molding composition comprising e.g. 2-methyl-propionic acid methyl ester - Google Patents

Abstract

Producing a composite part comprises following joint partners: (a) a molded part made of a polyamide molding composition and (b) a molded part made of a methacrylate copolymer molding composition, which contains the following monomer units: 2-methyl-propionic acid methyl ester-2,3-diyl and e.g. 2-methyl-propionic acid-2,3-diyl , where the molded part (a) and (b) are joined together by laser welding, either (a) or (b) is adjusted by a content of nanoscale laser-absorbing inorganic particles or organic laser absorbing dyes. Producing a composite part comprises following joint partners: (a) a molded part made of a polyamide molding composition (50 wt.%) and (b) a molded part made of a methacrylate copolymer molding composition (50 wt.%), which contains the following monomer units: 2-methyl-propionic acid methyl ester-2,3-diyl (15-99.9 wt.%), 2-methyl-propionic acid-2,3-diyl, an anhydride derivative of formula (IV), 2-methyl-propionic acid oxiranylmethyl ester-2,3-diyl or 2-(4,5-dihydro-oxazol-2-yl)-propan-1,2-diyl (0.1-30 wt.%), where the molded part (a) and (b) are joined together by laser welding, either (a) or (b) is adjusted by a content of nanoscale laser-absorbing inorganic particles or organic laser absorbing dyes. m : 0 or 1. [Image].

Description

The present invention relates to a method for producing a composite of a polyamide molding and a methacrylate copolymer molding in which the moldings are colored either uncolored or transparent, translucent or covered by means of a colorant, wherein the composite is produced by laser welding.

The welding of plastic parts by means of laser energy is known per se. The laser weldability is effected by absorbing the laser energy in the plastic material either directly by interaction with the polymer or indirectly with a laser-sensitive agent added to the plastic material. The laser-sensitive agent may be an organic dye or a pigment, which causes a local heating of the plastic by absorption of the laser energy. In laser welding, the plastic material is so strongly heated by absorption of the laser energy in the joining area that the material melts and weld both parts together.

In practice, the principle of bond formation between joining partners in laser welding relies on a joining partner facing the laser source having sufficient transparency for the light source of the laser source having a specific wavelength so that the radiation reaches the underlying joining partner where it is absorbed , As a result of this absorption heat is released, so that not only the absorbent, but also the laser-transparent material melts locally in the contact area of the two joining partners and both partially mix, whereby a composite is produced after cooling. Both parts are welded together as a result in this way.

The laser weldability is dependent on the nature of the plastic materials or the polymers underlying them, the nature and content of any laser-sensitive additives and the wavelength and radiation power of the laser used. In addition to CO ₂ lasers (infrared range) and excimer lasers (ultraviolet range), this technique mainly uses lasers in the visible range as well as in the near infrared range (NIR) such as Nd: YAG, diode, fiber and slab lasers.

Laser-weldable plastic materials containing laser-sensitive additives in the form of dyes and / or pigments generally have more or less pronounced coloration and / or lack of transparency. In practice, the equipment of the laser welding material to be adjusted as laser-absorbent is most frequently carried out by the introduction of soot.

In WO 02/36329 describes a method for laser welding plastic moldings, in which the laser beam is passed through a laser-transparent first molded part and in a laser-absorbing second molded part causes heating, whereby the weld is made. One molding contains laser-transparent dyes and the other molding laser-absorbing dyes or pigments that are coordinated so that a homogeneous color impression is formed in both moldings. Since, in particular, carbon black is used as the laser-absorbing additive, this molded part is naturally not transparent; In addition, only dark colors can be realized for the laser-absorbing molded part.

Basically, according to the doctrine of WO 02/36329 the laser-transparent joining partner and the laser-absorbing joining partner are adjusted in the same color. For this purpose, however, completely different colorants are needed. The skilled person depends here on trying out. However, such identical color settings with different colorants usually have a different aging behavior under environmental influence, so that different color changes result in use and over time.

The joining by laser welding of two plastic components with the color setting white / white, same color / same color, especially light color settings are difficult, or transparent to white or bright color settings is only unsatisfactory, difficult or not possible in individual cases by laser welding , There is therefore a need for plastic materials of said combinations which can be joined by laser welding.

The WO 2005/084956 teaches that highly transparent plastic materials are laser-markable or laser-weldable due to their content of nanoscale laser-sensitive metal oxides. The same teaches the WO 2005/084955 for plastic materials which are colored transparent, translucent or covered by colorants.

Injection molded or extruded moldings or films of methacrylate copolymers (eg, polymethacrylmethylimides (PMMI) or methyl methacrylate copolymers) are widely used because of their excellent transparency and other good optical and mechanical properties. Their chemical resistance and stress cracking resistance, however, is in many cases insufficient. Due to the better chemical resistance and stress cracking resistance, but slightly lower optical properties of the polyamides, one would like to use these in a composite with methacrylate copolymers. In this case, the transparency and the colorability of the individual moldings should not be affected.

• a) ein Formteil aus einer Polyamidformmasse sowie
• b) ein Formteil aus einer Methacrylatcopolymer-Formmasse, wobei die Formteile gemäß a) und b) durch Laserschweißen miteinander verbunden werden, dadurch gekennzeichnet, dass das laserabsorbierende Formteil durch einen Gehalt an nanoskaligen laserabsorbierenden anorganischen Partikeln oder organischen laserabsorbierenden Farbstoffen laserschweißbar ist.

This object has been achieved by a method for producing a composite part which contains the following joining partners:

• a) a molded part of a polyamide molding compound and
• b) a molding of a methacrylate copolymer molding composition, wherein the mold parts according to a) and b) are joined together by laser welding, characterized in that the laser-absorbent molding is laser-weldable by a content of nanoscale laser-absorbing inorganic particles or organic laser-absorbing dyes.

The moldings according to a) and b) can be transparent, opaque or colored by colorant transparent, translucent or covered.

In a first embodiment, the laser-absorbing joining partner consists of a transparent, laser-absorbing polyamide molding compound and the laser-transmitting joining partner of a transparent methacrylate copolymer molding compound.

In a second embodiment, the laser-absorbing joining partner consists of a transparent, laser-absorbing methacrylate copolymer molding compound and the laser-transmitting joining partner of a transparent polyamide molding compound.

In a third embodiment, the laser-absorbing joining partner consists of a laser-absorbing polyamide molding compound and the laser-transmitting joining partner of a transparent, translucent or covered colored methacrylate copolymer molding compound.

In a fourth embodiment, the laser-absorbing joining partner consists of a laser-absorbing, transparent, translucent or covered dyed polyamide molding compound and the laser-transmitting joining partner of a transparent methacrylate copolymer molding compound.

In a fifth embodiment, the laser-absorbing joining partner consists of a transparent, laser-absorbing methacrylate copolymer molding compound and the laser-transmitting joining partner of a transparent, translucent or covered dyed polyamide molding compound.

In a sixth embodiment, the laser-absorbing joining partner consists of a laser-absorbing, transparent, translucent or covered colored methacrylate copolymer molding compound and the laser-transmitting joining partner of a polyamide molding compound.

In a seventh embodiment, the laser-absorbing joining partner consists of a laser-absorbing, transparent, translucent or covered dyed polyamide molding compound and the laser-transmitting joining partner of a transparent, translucent or covered colored methacrylate copolymer molding compound.

In an eighth embodiment, the laser-absorbing joining partner consists of a laser-absorbing, transparent, translucent or covered colored methacrylate copolymer molding compound and the laser-transmitting joining partner of a transparent, translucent or covered dyed polyamide molding compound.

A transparent molding composition is to be understood as meaning a molding composition which, with a material thickness of 2 mm, has a transmission of more than 85% and in particular more than 90% and a haze of less than 3%, preferably less than 2% and in particular less than 1%. having. The determination of transmission and haze is carried out after ASTM D1003 ,

The composite part produced according to the invention may moreover also contain a plurality of molded parts according to a) and / or several molded parts according to b). It may also contain other components, which may consist of plastic, metal, wood, glass, ceramics or the like and in a suitable manner integrated in the composite part. In addition, fine mechanical and / or electronic components can be integrated into the composite part produced according to the invention as further components. In particular, in such cases, the associated with the laser welding great freedom of design as well as the targeted, only locally effective energy input, which thermally does not significantly burden the surrounding area of the weld, of particular advantage.

The polyamide of the molding according to a) is not subject to any restriction. Suitable examples are aliphatic homo- and copolycondensates, for example PA46, PA66, PA88, PA610, PA612, PA810, PA1010, PA1012, PA1212, PA6, PA7, PA8, PA9, PA10, PA11 and PA12. (The designation of the polyamides corresponds to international standard, where the first digit (s) indicate the C atomic number of the starting diamine and the last digit (s) the C atomic number of the dicarboxylic acid this means that it has been assumed that an α, ω-aminocarboxylic acid or the lactam derived therefrom; H. Domininghaus, The plastics and their properties, pages 272 et seq., VDI-Verlag, 1976. )

If copolyamides are used, these z. As adipic acid, sebacic acid, suberic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, etc. as co-acid or bis (4-aminocyclohexyl) methane, bis (3-methyl-4-aminocyclohexyl) methane, trimethylhexamethylenediamine, hexamethylenediamine or the like as codiamine contain. Lactams such as caprolactam or laurolactam or aminocarboxylic acids such as ω-aminoundecanoic acid can likewise be incorporated as cocomponent.

The preparation of these polyamides is known (eg. DB Jacobs, J. Zimmerman, Polymerization Processes, pp. 424-467, Interscience Publishers, New York, 1977 ; DE-AS 21 52 194 ).

In addition, as polyamides and mixed aliphatic / aromatic polycondensates are suitable, as z. Tie U.S. Patent No. 4,163,101 . 4 603 166 . 4 831 108 . 5,112,685 . 5 436 294 and 5,447,980 as well as in the EP-A-0 309 095 are described. These are usually polycondensates, the monomers of aromatic dicarboxylic acids such. As terephthalic acid and isophthalic acid, aliphatic dicarboxylic acids such as. As adipic acid, aliphatic diamines such. As hexamethylenediamine, nonamethylenediamine, dodecamethylenediamine and 2-methyl-1,5-pentanediamine and lactams or ω-aminocarboxylic acids such as. As caprolactam, laurolactam and ω-aminoundecanoic acid are selected. The content of aromatic monomer units in the polycondensate is generally at least 0.1%, at least 5%, at least 10%, at least 15%, at least 20%, at least 25%, at least 30%, at least 35%, at least 40%, at least 45% or about 50%, based on the sum of all monomer units. Such polycondensates are often referred to as "polyphthalamide" or "PPA". Further suitable polyamides are poly (etheresteramides) or poly (etheramides); Such products are z. Tie DE-OSS 25 23 991 . 27 12 987 and 30 06 961 described.

• – Das Polyamid aus 1,12-Dodecandisäure und 4,4'-Diaminodicyclohexylmethan (PA PACM12), insbesondere ausgehend von einem 4,4'-Diaminodicyclohexylmethan mit einem trans,trans-Isomerenanteil von 35 bis 65%;
• – PA612, PA1010, PA1012, PA11, PA12, PA1212 sowie Mischungen hieraus;
• – Copolyamide, die aus folgender Monomerkombination herstellbar sind: a) 65 bis 99 Mol-%, bevorzugt 75 bis 98 Mol-%, besonders bevorzugt 80 bis 97 Mol-% und insbesondere bevorzugt 85 bis 96 Mol-% eines im wesentlichen äquimolaren Gemisches aus einem aliphatischen unverzweigten Diamin und einer aliphatischen unverzweigten Dicarbonsäure, wobei das Gemisch gegebenenfalls als Salz vorliegt und darüber hinaus Diamin und Dicarbonsäure bei der Berechnung der Zusammensetzung jeweils einzeln gezählt werden, mit der Einschränkung, dass das Gemisch aus Diamin und Dicarbonsäure im Mittel 8 bis 12 C-Atome und bevorzugt 9 bis 11 C-Atome pro Monomer enthält; b) 1 bis 35 Mol-%, bevorzugt 2 bis 25 Mol-%, besonders bevorzugt 3 bis 20 Mol-% und insbesondere bevorzugt 4 bis 15 Mol-% eines im wesentlichen äquimolaren Gemisches aus einem cycloaliphatischen Diamin und einer Dicarbonsäure.

Polyamides which are particularly suitable for the purposes of the invention are:

• - The polyamide of 1,12-dodecanedioic acid and 4,4'-diaminodicyclohexylmethane (PA PACM12), in particular starting from a 4,4'-diaminodicyclohexylmethane with a trans, trans isomer content of 35 to 65%;
• PA612, PA1010, PA1012, PA11, PA12, PA1212 and mixtures thereof;
• Copolyamides which can be prepared from the following monomer combination: a) 65 to 99 mol%, preferably 75 to 98 mol%, particularly preferably 80 to 97 mol% and particularly preferably 85 to 96 mol% of a substantially equimolar mixture of an aliphatic unbranched diamine and an aliphatic unbranched dicarboxylic acid, wherein the mixture is optionally in the form of a salt and in addition diamine and dicarboxylic acid are counted individually in the calculation of the composition, with the proviso that the mixture of diamine and dicarboxylic acid averaged 8 to 12 C Atoms and preferably contains 9 to 11 C atoms per monomer; b) 1 to 35 mol%, preferably 2 to 25 mol%, particularly preferably 3 to 20 mol% and particularly preferably 4 to 15 mol% of a substantially equimolar mixture of a cycloaliphatic diamine and a dicarboxylic acid.

• – das Polyamid aus Terephthalsäure und/oder Isophthalsäure und dem Isomerengemisch aus 2.2.4- und 2.4.4-Trimethylhexamethylendiamin,
• – das Polyamid aus Isophthalsäure und 1.6-Hexamethylendiamin,
• – das Copolyamid aus einem Gemisch aus Terephthalsäure/Isophthalsäure und 1.6-Hexamethylendiamin, gegebenenfalls in Mischung mit 4.4'-Diaminodicyclohexylmethan,
• – das Copolyamid aus Terephthalsäure und/oder Isophthalsäure, 3.3'-Dimethyl-4.4'-diaminodicyclohexylmethan und Laurinlactam oder Caprolactam,
• – das (Co)Polyamid aus 1.12-Dodecandisäure oder Sebacinsäure, 3.3'-Dimethyl-4.4'-diaminodicyclohexylmethan und gegebenenfalls Laurinlactam oder Caprolactam,
• – das Copolyamid aus Isophthalsäure, 4.4'-Diaminodicydohexylmethan und Laurinlactam oder Caprolactam,
• – das Polyamid aus 1.1 2-Dodecandisäure und 4.4'-Diaminodicyclohexylmethan (bei niedrigem trans,trans-Isomerenanteil),
• – das Copolyamid aus Terephthalsäure und/oder Isophthalsäure sowie einem alkylsubstituierten Bis(4-aminocyclohexyl)methan-Homologen, gegebenenfalls in Mischung mit Hexamethylendiamin,
• – das Copolyamid aus Bis(4-amino-3-methyl-5-ethyl-cyclohexyl)methan, gegebenenfalls zusammen mit einem weiteren Diamin, sowie Isophthalsäure, gegebenenfalls zusammen mit einer werteren Dicarbonsäure,
• – das Copolyamid aus einer Mischung von m-Xylylendiamin und einem weiteren Diamin, z. B. Hexamethylendiamin, sowie Isophthalsäure, gegebenenfalls zusammen mit einer weiteren Dicarbonsäure wie z. B. Terephthalsäure und/oder 2,6-Naphthalindicarbonsäure,
• – das Copolyamid aus einer Mischung von Bis(4-amino-cyclohexyl)methan und Bis-(4-amino-3-methyl-cyclohexyl)methan sowie aliphatischen Dicarbonsäuren mit 8 bis 14 C-Atomen, sowie
• – Polyamide oder Copolyamide aus einer Mischung, die 1.14-Tetradecandisäure sowie ein aromatisches, arylaliphatisches oder cycloaliphatisches Diamin enthält.

Examples of largely amorphous polyamides which can be used according to the invention are:

• The polyamide of terephthalic acid and / or isophthalic acid and the isomer mixture of 2,2,4- and 2,4,4-trimethylhexamethylenediamine,
• The polyamide of isophthalic acid and 1,6-hexamethylenediamine,
• The copolyamide from a mixture of terephthalic acid / isophthalic acid and 1,6-hexamethylenediamine, optionally mixed with 4,4'-diaminodicyclohexylmethane,
• The copolyamide of terephthalic acid and / or isophthalic acid, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane and laurolactam or caprolactam,
• The (co) polyamide of 1,12-dodecanedioic acid or sebacic acid, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane and optionally laurolactam or caprolactam,
• The copolyamide of isophthalic acid, 4,4'-diaminodicyclohexylmethane and laurolactam or caprolactam,
• The polyamide of 1,1,2-dodecanedioic acid and 4,4'-diaminodicyclohexylmethane (at low trans, trans isomer content),
• The copolyamide of terephthalic acid and / or isophthalic acid and an alkyl-substituted bis (4-aminocyclohexyl) methane homolog, optionally mixed with hexamethylenediamine,
• The copolyamide of bis (4-amino-3-methyl-5-ethylcyclohexyl) methane, optionally together with a further diamine, and isophthalic acid, optionally together with a further dicarboxylic acid,
• - The copolyamide from a mixture of m-xylylenediamine and another diamine, z. For example, hexamethylenediamine, and isophthalic acid, optionally together with another dicarboxylic acid such as. Terephthalic acid and / or 2,6-naphthalenedicarboxylic acid,
• - The copolyamide of a mixture of bis (4-amino-cyclohexyl) methane and bis (4-amino-3-methyl-cyclohexyl) methane and aliphatic dicarboxylic acids having 8 to 14 carbon atoms, and
• - Polyamides or copolyamides of a mixture containing 1.14-tetradecanedioic acid and an aromatic, arylaliphatic or cycloaliphatic diamine.

These examples can be varied as much as possible by adding further components (eg caprolactam, laurolactam or diamine / dicarboxylic acid combinations) or by partial or complete replacement of starting components by other components.

In a preferred embodiment, a blend of a substantially amorphous polyamide and a partially crystalline polyamide is used. Such blends are transparent with suitable composition; they also have improved chemical and stress cracking resistance. Suitable compositions are known (e.g. EP 1 227 132 A1 ) or can be found by simple trial and error.

The polyamide molding compound, the usual additives for polyamides and additives such. As impact modifiers, flame retardants, stabilizers, UV absorbers, plasticizers, processing aids, glass fibers, fillers, antistatic agents, mold release agents, flow agents, nucleating agents or the like may be added. The amount of the said agents should be metered so that the desired properties are not seriously affected. For most applications it is desirable that the polyamide molding compound is sufficiently transparent at the layer thickness used; this must be taken into account when selecting the auxiliaries and additives. The polyamide molding composition contains at least 50% by weight, preferably at least 60% by weight, particularly preferably at least 70% by weight, particularly preferably at least 80% by weight and very particularly preferably at least 90% by weight of polyamide.

• 1. 15 bis 99,9 Gew.-%, bevorzugt 25 bis 99,4 Gew.-% und besonders bevorzugt 35 bis 99 Gew.-% an Monomereinheiten der Formel
  
• 2. 0 bis 75 Gew.-%, bevorzugt 0,1 bis 60 Gew.-% und besonders bevorzugt 10 bis 45 Gew.-% an Monomereinheiten der Formel
  
  mit m = 0 oder 1 und R = H, Methyl, Ethyl, Propyl, Butyl oder Phenyl;
• 3. 0,1 bis 30 Gew.-%, bevorzugt 0,6 bis 20 Gew.-% und besonders bevorzugt 1 bis 15 Gew.-% an Monomereinheiten, die ausgewählt sind aus Einheiten folgender Formeln:
  
  mit m = 0 oder 1;
  

The methacrylate copolymer of the molding according to b) contains the following monomer units:

• 1. 15 to 99.9 wt .-%, preferably 25 to 99.4 wt .-% and particularly preferably 35 to 99 wt .-% of monomer units of the formula
  
• 2. 0 to 75 wt .-%, preferably 0.1 to 60 wt .-% and particularly preferably 10 to 45 wt .-% of monomer units of the formula
  
  with m = 0 or 1 and R = H, methyl, ethyl, propyl, butyl or phenyl;
• 3. 0.1 to 30 wt .-%, preferably 0.6 to 20 wt .-% and particularly preferably 1 to 15 wt .-% of monomer units which are selected from units of the following formulas:
  
  with m = 0 or 1;
  

In any case, the copolymer may additionally contain monomer units of value, for example those derived from maleic diesters, fumaric diesters, itaconic esters, vinyl acetate, styrene, acrylonitrile, methyl acrylate, ethyl methacrylate or ethene, as long as the desired performance properties and transparency are not significantly impaired thereby.

In the simplest case, the methacrylate copolymer is a copolymer of methyl methacrylate and methacrylic acid, maleic anhydride (m = 0 in formula (IV)), glycidyl methacrylate or isopropenyloxazoline. Any units of the formula (II) (m = 0) which are present are derived from optionally N-substituted maleimide. Such copolymers can be prepared in a known manner by free radical polymerization.

When m = 1 units of formula (II) are present, such copolymers are referred to as polymethacrylimides or sometimes as polyglutarimides. These are products based on polymethyl methacrylate, in which two adjacent carboxylate groups have been converted to a cyclic acid imide. The imide formation is preferably carried out with methylamine at high temperature and high pressure in the presence of water, units of the formulas (III) and (IV) being formed by hydrolysis. The products and their production are known ( Hans R. Kricheldorf, Handbook of Polymer Synthesis, Part A, Publisher Marcel Dekker Inc. New York-Basel-Hong Kong, p 223 f., HG Elias, macromolecules, Hüthig and Wepf Verlag Basel-Heidelberg-New York ; US 2,146,209 A ; US 4,246,374 ). Substituting only with water, we obtain units of formulas (III) and (IV) by hydrolysis, without imide units (II) are formed.

The methacrylate copolymer molding composition can be adjusted to impact strength, for example by adding a core / shell rubber customary for molding compositions of this type. In addition, at less than 50 wt .-%, preferably at most 40 wt .-%, more preferably at most 30 wt .-% and particularly preferably at most 20 wt .-% other thermoplastics such as SAN (styrene / acrylonitrile Copolymer), ABS and / or polycarbonate. The methacrylate copolymer may also contain other auxiliaries and additives such. As stabilizers, processing aids, fillers and reinforcing agents, dyes, pigments and other conventional additives in the usual amounts. The amount of the said agents should be metered so that the desired properties are not seriously affected. For most applications, it is desirable that the methacrylate copolymer molding compound be sufficiently transparent at the layer thickness used; this must be taken into account when selecting the auxiliaries and additives. The methacrylate copolymer molding composition contains at least 50 wt .-%, preferably at least 60 wt .-%, more preferably at least 70 wt .-%, particularly preferably at least 80 wt .-% and most preferably at least 90 wt .-% methacrylate copolymer. Suitable molding compounds are state of the art, for example, reference is made to the PLEXIMID ^® from. Evonik.

The nanoscale laser-absorbing inorganic particles or organic laser-absorbing dyes used according to the invention absorb very strongly in the region of the near infrared (NIR, wavelength range of the light of 800 to 1500 nm) or at least in subregions of the NIR, while in the range of the visible spectrum (400 to 800 nm) nm) or only weakly absorb. The wavelength of the laser radiation used for welding is therefore preferably in the range of 800 to 1500 nm.

Laser-sensitive or laser-absorbing inorganic particles are understood as meaning all inorganic-metallic oxides, such as metal oxides, mixed metal oxides, complex oxides, metal sulfides, borides, phosphates, carbonates, sulfates, nitrides, etc., or mixtures of these compounds which absorb in the characteristic wavelength range of the laser to be used and which are thus able to absorb so much laser energy in the plastic matrix in which they are embedded that the matrix melts.

Under nanoscale is to be understood that the largest dimension of the discrete particles of these laser-absorbing inorganic additives is less than 1 micron, ie 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-absorbing inorganic additives is preferably from 1 to 500 nm and in particular from 5 to 100 nm. If the particle size is below 100 nm, the particles are no longer visible per se and do not impair the transparency of the plastic matrix.

In the plastic material, the content of laser-absorbing inorganic particles is suitably 0.0001 to 0.1 wt .-%, preferably 0.001 to 0.01 wt .-%, based on the plastic material. As a rule and for all suitable plastic materials, adequate laser weldability of the plastic matrix is effected in this concentration range.

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

As nanoscale laser-sensitive metal oxides for the production of highly transparent laser-markable and / or laser-weldable plastic materials are preferably doped indium oxide, doped tin oxide and doped antimony oxide into consideration.

Particularly suitable metal oxides 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.

The laser-absorbing inorganic additives to be used according to the invention are known per se and are also commercially available in nanoscale form, that is to say as discrete particles having sizes of less than 1 μm and in particular in the preferred size range, typically in the form of dispersions.

As a rule, the laser-absorbing inorganic additives in their form of delivery are present as agglomerated particles, for example as agglomerates, whose particle size can be between 1 μm and several mm. These can be incorporated by means of the method according to the invention under high shear in the plastic matrix, whereby the agglomerates are decomposed into the nanoscale primary particles.

The determination of the degree of agglomeration 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, nanoscale metal oxides can be produced by precipitation processes, such as in DE 100 22 037 described.

Organic laser-absorbing dyes are usually used in amounts of 0.001-0.5 wt .-%, based on the molding composition. Suitable organic laser-absorbing dyes may be, for example, polycyclic organic compounds. Particularly suitable are those from the classes of phthalocyanines, naphthalocyanines, perylenes, quaterylenes, terylenes, metal complexes, azo dyes, anthraquinones, squaric acid derivatives, immonium dyes and polymethines. As the laser radiation absorbing polycyclic organic compounds are particularly suitable quaterylene-3,4: 13,14-tetracarboxylic and di-Quaterylen-3,4-dicarboxylic (together referred to as "Quaterylencarbonsäureimide") and terylene-3,4: 11,12-tetracarbonsäi diimides and Terylene-3,4-dicarboxylic acid monoimides (collectively called "terylenecarboxylic imides" for short).

The quaterylene and terylenecarboxylic imides may be substituted or unsubstituted at the imide nitrogen atoms and / or at the ring skeleton; they preferably bear alkyl and / or aryl radicals on the imide nitrogens and are unsubstituted on the ring skeleton or carry 2 to 8 substituents. These compounds are from the EP-A-596 292 as well as the WO-A-96/22332 . 02/76988 . 02/66438 . 02/68538 and 03/104232 known. Suitable compounds are in the WO 2005/102672 described in detail; this disclosure is expressly incorporated herein.

In the case of colored transparent, translucent and opaque systems, the neutral intrinsic color of these nanoscale laser-sensitive additives is advantageous since free choice of color is made possible with the plastic materials.

Suitable colorants for the transparent, translucent or opaque coloring are those which have only a low intrinsic absorption in the region of interest between 800 and 1500 nm, ie are laser-transparent.

The nomenclature of the Color Index (CI) is used below to designate the colorants. All colorant designations such as Solvent Orange or Pigment Red 101 are CI designations. (For simplicity, the name component CI will be omitted from Table 1 below.) Table 1: Examples of laser-transparent colorants Colorant CI Preferred concentration w% Particularly preferred concentration w% Pigment Orange 64 0.01-0.5 0.015-0.05 Solvent Orange 60 0.01-1.0 0.01-0.5 Solvent Orange 106 0.01-1.0 0.01-0.5 Solvent Orange 111 0.01-1.0 0.01-0.5 Pigment Red 48 0.05-1.0 0.05-0.5 Pigment Red 101 0.005-0.5 0.01-0.3 Pigment Red 144 0.005-0.5 0.01-0.2 Pigment Red 166 0.005-0.5 0.01-0.2 Pigment Red 178 0.01-1.0 0.03-0.5 Pigment Red 254 0.01-1.0 0.03-0.5 Solvent Red 52 0.01-1.0 0.01-0.5 Solvent Red 111 0.01-1.0 0.01-0.5 Solvent Red 135 0.01-1.0 0.01-0.5 Solvent Red 179 0.01-1.0 0.01-0.5 Pigment Green 7 0.0005 to 1.0 0.0005-0.5 Pigment Green 17 0.01-1.0 0.03-0.5 Pigment Green 50 0.005-0.5 0.005-0.05 Solvent Green 3 0.01-1.0 0.01-0.5 Solvent Green 20 0.01-1.0 0.01-0.5 Pigment Blue 15 0.005-1.0 0.01-0.5 Pigment Blue 29 0.02-5.0 0.2-2.0 Pigment Blue 36 from 0.015 to 0.5 0.015 to 0.25 Pigment Yellow 93 0.1-1.0 0.1-0.5 Pigment Yellow 110 0.01-1.0 0.03-0.5 Pigment Yellow 150 0.0005-0.5 0.0005 to 0.25 Pigment Yellow 180 0.01-1.0 0.03-0.5 Pigment Yellow 184 0.005-0.5 0.005-0.25 Solvent Yellow 21 0.005-0.5 0.005-0.5 Solvent Yellow 93 0.005-1.0 0.005-0.5 Pigment Brown 24 0.005-0.5 0.005-0.15 Pigment Violet 19 0.01-1.0 0.03-0.5 Pigment Violet 13 0.01-1.0 0.01-0.5 Pigment Violet 46 0.01-1.0 0.01-0.5

Some of the colorants mentioned may be present in different structures, which differ slightly from one another. For example, pigments with different metal ions may be laked, resulting in different forms of the pigment. These forms are attached according to CI by attaching a colon and a numeral, for. B. Pigment Red 48 for the sodium laked pigment, Pigment Red 48: 1 laked with calcium, Pigment Red 48: 2 laked with barium, Pigment Red 48: 3 laked with strontium, Pigment Red 48: 4 laked with magnesium. The CI colorant designations referred to here are to be understood to include all forms or structures. They are listed in the Color Index.

The production of the laser-weldable plastic materials used according to the invention is carried out in a manner known per se according to common techniques and methods used in plastics production and processing. It is possible to enter the laser-absorbing additives before or during the polymerization or polycondensation in individual starting materials or Eduktgemische or add during the reaction, the known to those skilled in the specific manufacturing process for the plastics in question are used. In the case of 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 intermediate or end products can be mixed with the laser-absorbing 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, plasticizers, mold release agents, lubricants, dispersing aids, antistatic agents, but also fillers and reinforcing agents or impact modifiers etc. mixed and homogenized in customary devices and equipment such as reactors, stirred tanks, mixers, roller mills, extruders, etc., optionally shaped and then cured. The laser-absorbing additive is introduced into the material at the appropriate time and incorporated homogeneously. Particularly preferred is the incorporation of the laser-absorbing additive in the form of a concentrated masterbatch with the same or a compatible plastic material.

It is advantageous if the incorporation of the laser-absorbing additive into the plastic matrix takes place under high shear. 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.

The laser welding can be carried out on a commercially available laser, for. B. a laser from. Baasel, type StarMark SMM65, with a power between 0.1 and 22 amps and a feed rate between 1 and 100 mm / s done. When setting the laser energy and feed rate, make sure that the power is not too high and the feed speed is not too low to avoid unwanted charring. If the power is too low and the feed speed too high, the welding may be insufficient. For this purpose, the required settings can be determined in individual cases without further ado.

For welding plastic moldings or semifinished plastic products it is necessary that at least one of the parts to be joined at least in the surface region of the invention consists of laser-absorbing plastic material, wherein the joining surface with laser light, for which the additive contained in the plastic material is sensitive, irradiated. It is expedient to proceed in such a way that the joining part facing the laser beam does not absorb the laser energy and the second joining part consists of laser-absorbing plastic material according to the invention, whereby it is heated to such an extent at the phase boundary that the two parts weld together. A certain contact pressure is required to obtain a material connection.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 02/36329 [0006, 0007]
• WO 2005/084956 [0009]
• WO 2005/084955 [0009]
• DE 2152194 A [0025]
• US 4163101 [0026]
• US 4603166 [0026]
• US 4831108 [0026]
• US 5,112,685 [0026]
• US 5436294 [0026]
• US 5447980 [0026]
• EP 0309095 A [0026]
• DE 2523991 [0026]
• DE 2712987 [0026]
• DE 3006961 [0026]
• EP 1227132 A1 [0030]
• US 2146209A [0035]
• US 4246374 [0035]
• EP 1142830A [0048]
• EP 1270511A [0048]
• DE 10311645 [0048]
• DE 10022037 [0048]
• EP 596292 A [0050]
• WO 96/22332 A [0050]
• WO 02/76988 [0050]
• WO 02/66438 [0050]
• WO 02/68538 [0050]
• WO 03/104232 [0050]
• WO 2005/102672 [0050]

Cited non-patent literature

• ASTM D1003 [0021]
• H. Domininghaus, The Plastics and Their Properties, pages 272 et seq., VDI-Verlag, 1976. [0023]
• DB Jacobs, J. Zimmerman, Polymerization Processes, pp. 424-467, Interscience Publishers, New York, 1977 [0025]
• Hans R. Kricheldorf, Handbook of Polymer Synthesis, Part A, Publisher Marcel Dekker Inc., New York-Basel-Hong Kong, p. 223 f., HG Elias, Makromolekule, Hüthig and Wepf Verlag Basel-Heidelberg-New York [0035]
• DIN 53206 (from August 1972) [0047]

Claims (9)

Process for producing a composite part which contains the following joining partners: a) a molding of a polyamide molding composition which contains at least 50% by weight of polyamide, and b) a molding of a methacrylate copolymer molding composition containing at least 50% by weight of methacrylate copolymer, which contains the following monomer units: 1. 15 to 99.9% by weight of monomer units of the formula

2. 0.1 to 30% by weight of monomer units selected from units of the following formulas:

with m = 0 or 1;

wherein the molded parts according to a) and b) are joined together by laser welding, characterized in that either the shaped part according to a) or the shaped part according to b) is adjusted to be laser-absorbent by a content of nanoscale laser-absorbing inorganic particles or organic laser-absorbing dyes. A method according to claim 1, characterized in that the composite part contains a plurality of molded parts according to a) and / or several molded parts according to b). Method according to one of the preceding claims, characterized in that the methacrylate copolymer additionally contains 0.1 to 75 wt .-% of monomer units of the formula

with m = 0 or 1 and R = H, methyl, ethyl, propyl, butyl or phenyl. Method according to one of the preceding claims, characterized in that the particle size of the nanoscale laser-absorbing inorganic particles is 1 to 500 nm and preferably 5 to 100 nm. Method according to one of the preceding claims, characterized in that the content of nanoscale laser-absorbing inorganic particles from 0.0001 to 0.1 wt .-% and preferably 0.001 to 0.01 wt .-%, based on the molding composition, is. A method according to any one of claims 1 to 3, characterized in that the content of organic laser-absorbing dyes from 0.001 to 0.5 wt .-%, based on the free mass. A method according to any one of claims 1 to 3 and 6, characterized in that the organic laser-absorbing dye is a polycyclic organic compound. Method according to one of claims 1 to 5, characterized in that metal oxides, mixed metal oxides, complex oxides, metal sulfides, borides, phosphates, carbonates, sulfates, nitrides or mixtures of these compounds are used as nanoscale laser-absorbing inorganic particles. Composite part, produced according to one of the preceding claims.