DE19702424A1 - Process for the labeling of molded bodies - Google Patents

Abstract

The invention concerns a method of inscribing by means of high-energy radiation mouldings based on thermoplastic polymers A) or mixtures of these polymers with up to 70 wt %, relative to the total weight of the components, of further additives and processing aids. The invention is characterized in that a vinylaromatic polymer B) is used as additive for improving inscribability, this polymer having been modified by the incorporation of at least one functional group selected from the series comprising carbonyl, carboxylic acid, acid anhydride, acid amide, acid imide, carboxylic acid ester, carboxylate, amino, hydroxyl, epoxy, oxazolin, urethane, urea, lactam or benzyl halide groups.

Description

The present invention relates to an improved method for Labeling of thermoplastic polymers using energierei radiation.

Plastics can be labeled using printing processes. In In the last few years, however, laser marking has come a long way going through. The advantages are that it is easy, quick and precisely feasible, non-contact (neither mechanical Load still contamination of the workpiece) flexible (computer controlled), clean and chemical-free processing. Laser on layers can be easily added to automatic production lines integrate; Plastic prefabricated parts can be individually labeled because changing the layout is computer-aided and easy is possible quickly. The labeling is also contactless in hard-to-reach places. Compared to conventional Be printing techniques result in considerable advantages.

The most important characterization quantity of the inscription obtained is the legibility, which can be quantified with the contrast can. In addition to high contrast, there are sufficient depth of discoloration and the smoothest possible surface is required. The writing is supposed to be resistant to abrasion and chemicals.

With this, a high-quality marking on a plastic molding arises, the absorption of laser light must have a color change cause a reaction. Depending on the wavelength, radiated power, Pulse length etc. are each different interactions between laser light and plastic dominating and one under therefore separates a number of different laser-induced mecha mechanisms that lead to permanent marking: Thermochemi cal reaction, carbonization of the surface, melting, order melting, evaporation, sublimation, engraving, discoloration, on foaming, photochemical reaction, ablation (material removal), Fading of dyes, removal of a coating layer.

There are two methods of laser marking, the Mas ken (projection) and beam deflection labeling (scanning of the laser beam). When writing masks, pulsed lasers are used used. A laser beam with a sufficiently large aperture be a mask lights up that shows all the information to be transmitted contains. The mask is attached to the one to be labeled with a lens Surface mapped, the information can be with a single Laser pulse can be applied to the workpiece. With large bil The mask can then be scanned with several pulses. the The maximum size of the labeling field is determined by the necessary Energy density limited. The projection method thus allows quick lettering; since a mask must be created is however, it is not that flexible. With the beam deflection labeling the laser beam goes through two moveable mirrors and a plan field lens directed onto the workpiece to be marked.

So far, the CO ₂ laser (10.6 µm wavelength) and in particular the Nd: YAG laser (1.06 µm) or the frequency-doubled Nd: YAG laser (532 nm) have mainly been used. Often, however, the absorption coefficient of the plastics to be processed is not high enough at these wavelengths to induce a color change in the polymer material. For this reason, suitable auxiliaries and fillers are usually added to the plastic during its production, which absorb strongly at the wavelength used and transfer the absorbed energy to the surrounding polymer matrix (e.g. addition of sensitizing dyes in the form of pigments, addition of toxic arsenic or Cd compounds, addition of suitable monomers during the copolymerization, coating of the substrate with special paint and paint films, inks, etc.) The incorporation of carbon black (DE-A 29 36 926) or bone carbon (EP-A 522 370) is known ) or from antimony trioxide in thermoplastic elastomers. Special plastic additives with high absorption capacity, especially for the wavelength of the Nd: YAG laser, enable markings with high contrast, good contour sharpness and good abrasion resistance (C. Herkt-Maetzky, Kunst materials 81 (1991) 4). Other processes work with radiation-sensitive, bleachable additives (and possibly additional, less radiation-sensitive, non-discolored compounds). The radiation-sensitive dyes are then destroyed by irradiation and the background or complementary color of the polymer matrix remains at the irradiated areas and a visual, colorful contrast marking is created. Such color changes lead to good contrasts (EP-A 327 508). Plastics that contain commercially available colored pigments can be labeled with the frequency-doubled Nd: YAG laser, as a large number of pigments and dyes absorb at 532 nm. The pigments are bleached out with the consequence of a color change. By adding modified mica pigments, molding compounds can be produced that can be _{labeled with the CO 2} laser (C. Herkt-Maetzky, Kunststoffe 81 (1991) 4). A process has also been described in which pigments are applied to a carrier material, which pigments are melted thermally into the surface with the aid of the laser (EP-A 419 377).

From EP 400 305 it is known copper hydroxyphosphates and others use colorless additives such as molybdenum sulfide in order to to improve the writing ability, especially of polyesters.

Other aromatic compounds to improve laser performance writability are known from EP-A 249 082 and WO 95/01580.

Modifying plastics is time-consuming. The added filling substances can negatively affect the material properties of the plastic influence. Additives can be used to improve the inscribable often unintended side effects such as decreased Strength of the material or undesirable colors when in use of pigments. Therefore, a special laser was used Looking for sensitive additives that are incorporated into the plastic tet, other application-related material properties are not included influence.

The object of the present invention was therefore to provide a method for labeling moldings based on thermo plastic plastics available, which the does not have disadvantages described above and the Erstel development of permanent high-contrast fonts on technically simple way to be realized.

Especially for natural-colored or light-colored polyesters be there is a need to improve laser markability As far as possible preservation of high long-term use temperature, good Abrasion resistance, good mechanics and dimensional stability of the Polyester.

This object is achieved according to the invention by a method according to The preamble of claim 1 solved, being used as an additive for Improve the writability of a vinyl aromatic poly mer B) is used, which by installing at least one func nellen group selected from the series of carbonyl, carbon acid, acid anhydride, acid amide, acid imide, carboxylic acid ester, carboxylate, amino, hydroxyl, epoxy, oxazoline, ure than, urea, lactam or halobenzyl groups modified became.

The energy-rich one used in the process according to the invention Radiation generally has a wavelength in the range of 150 to 1500, preferably in the range of 150-1100 nm.

For example, CO ₂ lasers (10.6 µm) and Nd: YAG lasers (1064 or 532 nm) or UV lasers may be mentioned here, the latter being in particular excimer lasers with the following wavelengths:

F ₂ excimer laser 157 nm ArF excimer laser 193 nm KrCl excimer laser 222 nm KrF excimer laser 248 nm XeCl excimer laser 308 nm XeF excimer laser 351 nm

as well as frequency-multiplied Nd: YAG lasers with wavelengths of 355 nm (frequency tripled) or 266 nm (frequency quadrupled).

Nd: YAG lasers (1064 or 532 nm) are particularly preferred, KrF laser (248 nm) and XeCl laser (308 nm).

The energy densities of the lasers used are generally in the range from 0.3 mJ / cm ² to 50 J / cm ^2, preferably 0.5 mJ / cm ² to 20 J / cm ² and particularly preferably 1 mJ / cm ² to 10 J / cm ² .

When using pulsed lasers, the pulse frequency is im generally in the range from 0.1 to 10,000, preferably from 0.5 up to 5000 and in particular from 1 to 1000 Hz and the pulse lengths (Duration of the individual pulses) in the range from 0.1 to 1000 preferably from 0.5 to 500 and particularly preferably from 1 to 100 ns.

Depending on the energy density of the laser used, the pulse The length and type of the irradiated molding are sufficient for education Development of good lettering generally 1 to 20,000, preferably show 1 to 5000 and in particular 1 to 3000 pulses.

Corresponding lasers that are incorporated in the method according to the invention are commercially available.

Excimer lasers are particularly suitable for projection (Mas method). But it is also possible to move the beam with mirroring (scanning). With a homogeneous beam cross cut the irradiation of a mask of about 2 cm × 2 cm is possible lich. By using suitable optics, the beam can cross cut but also further expanded.

With excimer lasers, you can write well with just one pulse are (with appropriately adapted energy density), so that in Compared to Nd: YAG lasers also very fast markings can be produced. In the series production of injection molded parts z. B. the inscription time must be less than the injection molding time (<approx. 30 s) divided by the number of cavities. From it it follows that in these cases the injection molded forms with high Velocities need to be labeled. Such high Ge speeds are sometimes not possible with the Nd: YAG laser Lich, but only achievable with 1-pulse mask bombardment.

Even higher demands on the marking speed provide continuous processes such as B. profile extrusion with Material speeds of several m / s. Enough for this not even the high writing speeds of Nd: YAG lasers the end.

Continuous radiation sources can also be used UV lamps such as mercury, xe or deuterium lamps can be used. Even such products are commercially available.

According to the process of the invention, moldings are on the Base of thermosetting or thermoplastic polymers or Mixtures of these polymers with up to 70 wt .-%, based on the Total weight of the components, other additives and processing Processing aids labeled using high-energy radiation.

Basically, the beneficial effect can be seen with plastics of any kind. A list of suitable thermoplastics A) can be found for example in the plastic pocket book (Ed. Saechtling), Edition 1989, where sources of supply are also mentioned. Procedure for Manufacture of such thermoplastics are the subject man known per se. Below are some preferred arts types of material explained in more detail.

1. Polyoxymethylene homo- or copolymers

Such polymers are known per se to the person skilled in the art and are described in described in the literature.

Quite generally, these polymers have at least 50 mol% of recurring —CH ₂ O— units in the main polymer chain.

The homopolymers are generally made by polymerizing Formaldehyde or trioxane produced, preferably in the counter waiting for suitable catalysts.

In the context of the invention, polyoxymethylene copolymers are given before given, in particular those which, in addition to the recurring units -CH ₂ O-, have up to 50, preferably 0.1 to 20 and in particular 0.3 to 10 mol% of recurring units

contain, where R ¹ to R ⁴ independently of one another a hydrogen atom, a C ₁ - to C ₄ alkyl group or a halogen-substituted alkyl group with 1 to 4 carbon atoms and R ⁵ a -CH ₂ -, -CH ₂ O-, a C ₁ to C ₄ alkyl or C ₁ to C ₄ haloalkyl substituted methyl groups or a corresponding oxymethylene group and n has a value in the range from 0 to 3. These groups can advantageously be introduced into the copolymers by ring opening of cyclic ethers. Preferred cyclic ethers are those of the formula

where R ¹ to R ⁵ and n have the meaning given above. Ethylene oxide, 1,2-propylene oxide, 1,2-butylene oxide, 1,3-butylene oxide, 1,3-dioxane, 1,3-dioxolane and 1,3-dioxepane as cyclic ethers and linear oligo- or may be mentioned only as examples Polyformals such as polydioxolane or polydioxepane are called comonomers.

Also suitable are oxymethylene terpolymers which are prepared, for example, by reacting trioxane, one of the cyclic ethers described above, with a third monomer, preferably a bifunctional compound of the formula

where Z is a chemical bond, -O-, -ORO- (R = C ₁ - to C ₈ -alkylene or C ₂ - to C ₈ -cycloalkylene).

Preferred monomers of this type are ethylene diglycid and diglycidyl ethers and diethers from glycidyls and formaldehyde, dioxane or Trioxane in a molar ratio of 2: 1 and diether from 2 mol glycidyl compound and 1 mol of an aliphatic diol with 2 to 8 carbon atoms such as the diglycidyl ethers of ethylene glycol kol, 1,4-butanediol, 1,3-butanediol, cyclobutane-1,3-diol, 1,2-pro pandiol and cyclohexane-1,4-diol, to name but a few examples to name.

Process for the preparation of the above-described homo- and Copolymers are known to the person skilled in the art and be in the literature so that further details are not necessary here.

The preferred polyoxymethylene copolymers have melting points of at least 150 ° C and molecular weights (weight average) Mw im Range from 5,000 to 200,000, preferably from 7,000 to 150,000.

End group-stabilized polyoxymethylene polymers which are attached to the Chain ends having C-C bonds are particularly preferred.

2. Polycarbonates and polyesters

Suitable polycarbonates are known per se. You are e.g. B. ent speaking the method of DE-B-13 00 266 through interfaces polycondensation or according to the method of DE-A-14 95 730 obtainable by reacting biphenyl carbonate with bisphenols. The preferred bisphenol is 2,2-di (4-hydroxyphenyl) propane, in general common - as also in the following - referred to as bisphenol A.

Instead of bisphenol A, other aromatic di hydroxy compounds are used, in particular 2,2-di (4-hydroxyphenyl) pentane, 2,6-dihydroxynapthalene, 4,4'-dihy hydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy diphenyl sulfite, 4,4'-dihydroxydiphenylmethane, 1,1-di- (4-hydroxy phenyl) ethane or 4,4-dihydroxydiphenyl and mixtures of the above mentioned dihydroxy compounds.

Particularly preferred polycarbonates are those based on Bisphenol A or bisphenol A together with up to 30 mol .-% of the aforesaid aromatic dihydroxy compounds.

The relative viscosity of these polycarbonates is in general in the range from 1.1 to 1.5, in particular 1.28 to 1.4 (measured at 23 ° C in a 0.5 wt .-% solution in dichloromethane).

Suitable polyesters are also known per se and are described in the literature. They contain an aromatic ring in the main chain, which is derived from an aromatic dicarboxylic acid. The aromatic ring can also be substituted, e.g. B. by halogen such as chlorine and bromine or by C ₁ -C ₄ alkyl groups such as methyl, ethyl, i- or n-propyl and n-, i- or tert-butyl groups.

The polyesters can be made by reacting aromatic dicarbon acids, their esters or other ester-forming derivatives of the same ben with aliphatic dihydroxy compounds in known per se Way to be made.

Such polyalkylene terephthalates are known per se and are described in the literature. They contain an aromatic ring in the main chain that comes from the aromatic dicarboxylic acid. The aromatic ring can also be substituted, e.g. B. by Ha logen such as chlorine and bromine or by C ₁ -C ₄ alkyl groups such as methyl, ethyl, i- or n-propyl and n-, i- or t-butyl groups.

These polyalkylene terephthalates can be obtained by reacting aroma table dicarboxylic acids, their esters or other ester-forming Derivatives with aliphatic dihydroxy compounds in per se be can be produced in a known manner.

Preferred dicarboxylic acids are 2,6-naphthalenedicarboxylic acid, Terephthalic acid and isophthalic acid or mixtures thereof nen. Up to 30 mol%, preferably not more than 10 mol% of the aromatic dicarboxylic acids can be aliphatic or cyclo aliphatic dicarboxylic acids such as adipic acid, azelaic acid, Sebacic acid, dodecanedioic acids and cyclohexanedicarboxylic acids are set.

Of the aliphatic dihydroxy compounds, diols with 2 up to 6 carbon atoms, in particular 1,2-ethanediol, 1,4-butane diol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol, 1,4-Cy clohexanedimethylanol and neopentyl glycol or mixtures thereof preferred.

Particularly preferred polyesters (A) are polyalkylene tereph thalates, which are derived from alkanediols with 2 to 6 carbon atoms, to call. Of these, polyethylene terephthalate in particular is used and polybutylene terephthalate or mixtures thereof are preferred.

The viscosity number of the polyester (A) is generally in Be ranging from 60 to 220, preferably from 100 to 150 (measured in a 0.5% by weight solution in a phenol / o-dichlorobenzene mixed (weight ratio 1: 1 at 25 ° C).

Particularly preferred are polyesters, their carboxyl end groups content up to 100 meq / kg, preferably up to 50 meq / kg and ins especially up to 40 meq / kg polyester. Such poly Esters can, for example, by the method of DE-A 44 01 055 getting produced. The carboxyl end group content becomes more common wisely determined by titration methods (e.g. potentiometry).

Fully aromatic polyesters should be mentioned as a further group differ from aromatic dicarboxylic acids and aromatic dihydroxy derive connections.

As aromatic dicarboxylic acids are already suitable for the Polyalkylene terephthalates described compounds. Preferred are mixtures of 5 to 100 mol% isophthalic acid and 0 to 95 mol% terephthalic acid, especially mixtures of about 80% Terephthalic acid with 20% isophthalic acid to about equivalent Mixtures of these two acids are used.

The aromatic dihydroxy compounds preferably have the general formula I.

in which Z is an alkylene or cycloalkylene group with up to 8 carbon atoms, an arylene group with up to 12 carbon atoms, a carbonyl group, a sulfonyl group, an oxygen or sulfur atom or a chemical bond and in which m is the value 0 to 2 has. The compounds I can also _{carry C 1} -C ₆ -alkyl or alkoxy groups and fluorine, chlorine or bromine as substituents on the phenylene groups.

As the main body of these compounds, for example
Dihydroxydiphenyl,
Di- (hydroxyphenyl) alkane,
Di- (hydroxyphenyl) cycloalkane,
Di- (hydroxyphenyl) sulfide,
Di- (hydroxyphenyl) ether,
Di- (hydroxyphenyl) ketone,
Di (hydroxyphenyl) sulfoxide,
α, α'-di (hydroxyphenyl) dialkylbenzene,
Di- (hydroxyphenyl) sulfone, di- (hydroxybenzoyl) benzene
Resorcinol and hydroquinone as well as their nucleus alkylated or nucleus halogenated derivatives are mentioned.

Of these will be
4,4'-dihydroxydiphenyl,
2,4-di (4'-hydroxyphenyl) -2-methylbutane
α, α'-di- (4-hydroxyphenyl) -p-diisopropylbenzene,
2,2-di- (3'-methyl-4'-hydroxyphenyl) propane and
2,2-di- (3'-chloro-4'-hydroxyphenyl) propane,
as well as in particular
2,2-di (4'-hydroxyphenyl) propane
2,2-di- (3 ', 5-dichlorodihydroxyphenyl) propane,
1,1-di- (4'-hydroxyphenyl) cyclohexane,
3,4'-dihydroxybenzophenone,
4,4'-dihydroxydiphenyl sulfone and
2,2-Di- (3 ', 5'-dimethyl-4'-hydroxyphenyl) propane or mixtures thereof are preferred.

Mixtures of polyalkylenes can of course also be used use terephthalate and fully aromatic polyesters. These generally contain 20 to 98% by weight of the polyalkylene tereph thalates and 2 to 80% by weight of the wholly aromatic polyester.

Of course, polyester block copolymers such as Copolyetherester can be used. Such products are on known and in the literature, e.g. B. in US-A 3,651,014, described. Corresponding products are also available in stores lich, z. B. Hytrel® (DuPont).

Preferred dicarboxylic acids are naphthalenedicarboxylic acid, Terephthalic acid and isophthalic acid or mixtures thereof nen. Up to 10 mol% of the aromatic dicarboxylic acids can by aliphatic or cycloaliphatic dicarboxylic acids such as Adipic acid, azelaic acid, sebacic acid, dodecanedioic acids and Cyclohexanedicarboxylic acids are replaced.

Of the aliphatic dihydroxy compounds, diols with 2 up to 6 carbon atoms, in particular 1,2-ethanediol, 1,4-butane diol, 1,6-hexanediol, 1,4-hexanediol, 1,4-cyclohexanediol, and neo pentyl glycol or mixtures thereof are preferred.

Particularly preferred polyesters are polyalkylene terephthalates, which are derived from alkanediols with 2 to 6 carbon atoms, to NEN nen. Of these, in particular, polyethylene terephthalate, Polyethylene naphthalate and polybutylene terephthalate are preferred.

The viscosity number of the polyesters is generally in the range from 60 to 200 ml / g (measured in a 0.5% by weight solution in a phenol / o-dichlorobenzene mixture (weight ratio 1: 1) at 23 ° C).

3. polyolefins

Here are very general polyethylene and polypropylene as well Copolymers based on ethylene or propylene, possibly also to mention with higher α-olefins. Corresponding products are under the trade names Lupolen® and Novolen® from BASF Public company available.

4. Polymethacrylates

These include, in particular, polymethyl methacrylate (PMMA) as well Copolymers based on methyl methacrylate with up to 40% by weight of other copolymerizable monomers called, like them for example under the names Lucryl® from BASF Aktiengesellschaft or Plexiglas® from Röhm GmbH are available.

5. polyamides

The polyamides of the molding compositions according to the invention generally have mean a viscosity number of 90 to 350, preferably 110 to 240 ml / g determined in a 0.5% by weight solution in 96% strength by weight sulfuric acid at 25 ° C. according to ISO 307.

Semi-crystalline or amorphous resins with a molecular weight (Weight average) of at least 5000, as z. Tie American patents 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 be are preferred.

Examples are polyamides, which vary from lactams with 7 to 13 ring members derive, such as polycaprolactam, polycapryllactam and polylaurolactam as well as polyamides obtained by reacting Dicarboxylic acids can be obtained with diamines.

As dicarboxylic acids are alkanedicarboxylic acids with 6 to 12, esp special 6 to 10 carbon atoms and aromatic dicarboxylic acids applicable. Here are just adipic acid, azelaic acid, sebacin acid, dodecanedioic acid and terephthalic and / or isophthalic acid as Called acids.

Alkanediamines with 6 to 12 ins are particularly suitable as diamines special 6 to 8 carbon atoms and m-xylylenediamine, Di- (4-aminophenyl) methane, di- (4-aminocyclohexyl) methane, 2,2-di- (4-aminophenyl) -propane or 2,2-di- (4-aminocyclohexyl) -propane.

Preferred polyamides are polyhexamethylene adipamide, poly hexamethylene sebacic acid amide and polycaprolactam and copoly amide 6/66, in particular with a proportion of 5 to 95% by weight Caprolactam units.

In addition, polyamides should also be mentioned, the z. B. by Condensation of 1,4-diaminobutane with adipic acid under increased Temperature are available (polyamide-4,6). production method for polyamides of this structure are z. B. in EP-A 38 094, EP-A 38 582 and EP-A 39 524 are described.

Furthermore, polyamides are obtained by copolymerizing two or several of the aforementioned monomers are available, or Mixtures of several polyamides are suitable, the Mischungsver ratio is arbitrary.

Furthermore, such partially aromatic copolyamides as PA 6 / 6T and PA 66 / 6T proved to be particularly advantageous, their Triamine content less than 0.5, preferably less than 0.3% by weight is (see EP-A 299 444).

The preparation of the preferred partially aromatic copolyamides with low triamine content can according to the EP-A 129 195 and 129 196 are carried out.

Mixtures (blends) of such Po can of course also be used polymers are used.

The weight percentage of thermoplastics is in generally in the range of 20 to 99.99; preferably 45 to 99.98 and especially from 90 to 99.98% by weight.

In addition, the plastics can be 0 to 70, preferably 0 to 50% by weight of other additives and processing aids medium included. Examples are fibrous or particulate Fillers such as glass fibers or mineral fillers such as Wollastonite, rubber-elastic polymers (e.g. EP-, EPDM-Kaut schuke, TPU's, core-shell polymers, ABS, SAN or ASA poly mers), UV stabilizers, nucleating agents, flame retardants, Plasticizers, antioxidants and heat stabilizers ge called.

As an additive to improve the writability, the contain Moldings to be inscribed by the process according to the invention a vinyl aromatic polymer B), which by incorporation at least a functional group selected from the series Carbonyl, carboxylic acid, acid anhydride, acid amide, acid imide, Carboxylic acid ester, carboxylate, amino, hydroxyl, epoxy, oxa zoline, urethane, urea, lactam or halobenzyl groups has been modified.

The modified vinyl aromatic polymer is in amounts of 0.01 to 30, preferably from 1 to 20 and in particular from 1 to 10% by weight, based on the total weight of the components in the Mixture included.

Suitable vinyl aromatic polymers are styrene, ring-alkylated Styrenes or α-alkylstyrenes or halogenated styrenes such as chlorine styrene or mixtures thereof, the vinyl aromatic polymer up to 70% by weight, preferably up to 50% by weight, of further suitable ones Comonomer units e.g. B. from (meth) acrylonitrile or (meth) acrylic may contain acid esters.

_{Vinyl esters such as vinyl C 2} to C ₁₀ alkyl esters, in particular vinyl acetate, may be mentioned as further preferred comonomers. Examples of preferred acrylic esters are acrylic esters with 2 to 10 carbon atoms in the alcohol component, such as ethyl, propyl, butyl, hexyl, -2-ethylhexyl acrylate, preferably butyl acrylate. In addition to these monomers, other copolymerizable monomers which do not react with the functional groups can also be used. N-phenyl maleimide is an example of such copolymerizable monomers.

The vinyl aromatic polymers can be random copolymers or block copolymers. In addition, such polymers can also be graft (co) polymers, for example with a rubber-elastic graft base and one or more grafts. Natural rubber, synthetic rubber or polymers based on conjugated dienes, and elastomers based on C ₁ - to C ₁₀ -alkyl esters of acrylic acid or crosslinked siloxanes can, for. B. serve as a graft base.

Polystyrene-co-acrylonitrile, terpolymers based on styrene, Acrylonitrile and N-phenylmaleiimide, graft copolymers such as so-called called acrylonitrile / butadiene / styrene (ABS), acrylic acid ester / styrene / acrylic nitrile (ASA) or acrylonitrile / ethylene / styrene (AES) chew chuke and hydrogenated or non-hydrogenated nitrile rubbers based on acrylic esters, vinyl esters, dienes and acrylonitrile, as described in DE-A 33 02 124 are among the be preferred vinyl aromatic polymers.

The average molecular weight (M _w ) of these known polymers is generally in the range from 1,500 to 2,000,000, preferably from 10,000 to 1,000,000 and in particular from 15,000 to 800,000.

Usually, the vinyl aromatic polymer is incorporated by incorporating the groups already listed above have been modified. Appropriate process for production are, inter alia. in WO 89/1962, EP-A 146 965, US-A 4,474,923, US-A 4,508,896 and US-A 3,509,235.

Suitable modifiers are, for example, maleic acid, methyl maleic acid, itaconic acid, tetrahydrophthalic acid, their anhydrides and imides, fumaric acid, the mono- and diesters of these acids, e.g. B. of C ₁ - and C ₂ -C ₈ alkanols, the mono- or diamides of these acids such as N-phenylmaleimide, maleic hydrazide. Other modifying agents are the acid chloride of trimelitic anhydride, benzene-1,2-dicarboxylic anhydride-4-carboxylic acid-acetic acid anhydride, chloroethanoylsuccinaldehyde, chloroformylsuccinaldehyde, citric acid and hydroxysuccinic acid, and N-vinylpyrrolactone and (meth) acryloyl.

The modifying agents are usually in amounts from 0.1 to 10, preferably from 1 to 8% by weight, based on the modified vinyl aromatic polymer.

The modifying agents can be grafted or copolymers sation with vinyl aromatic monomers or their mixtures with other suitable comonomers listed above into the Chain can be introduced.

Particularly preferred modifiers are oxazoline groups containing monomers such as vinyloxazoline or isopropenyloxazoline.

Are vinyl aromatic polymers modified with oxazoline groups obtainable by the processes already mentioned. Contains that vinyl aromatic polymer is a comonomer containing nitrile groups it is advantageous to react the nitrile groups with 1,2-amino alcohols zen, being oxazoline-containing vinyl aromatic polymers (see H. Witte, W. Seeliger, Liebigs's Ann. Chem. 1974, P. 996).

The reaction can be in solution (JP-A 05/160392) or in the If appropriate, melt with the addition of suitable catalysts follow (DE-A 196 06 198).

Particularly preferred modified vinyl aromatic polymers are Styrene / acrylonitrile / isopropenyloxazoline copolymers and styrene / iso propenyloxazoline copolymers.

The thermoplastic molding compositions can be made according to those known per se Process can be prepared by using the starting components in conventional mixing devices such as screw extruders, Brabender-Mü hlen or Banbury mills and then extruded. After the extrusion, the extrudate can be cooled and shredded will. Individual components can also be premixed and then the remaining starting materials individually and / or also be added mixed. The mixing temperatures are in the Usually at 230 to 290 ° C.

The labeled moldings show a very good contrast, in particular the mechanical properties as far as possible remain. These are particularly suitable for applications in the electrical and electronics sector as keyboard caps, connectors bonds, capacitor housings, lamp sockets, fuse switch and switch base.

Examples Component A)

Polybutylene terephthalate with a viscosity number of 110 ml / g and a carboxyl end group content of 34 meq / kg (Ultradur B 2550 from BASF AG) (VZ measured in 0.5% strength by weight solution of Phe nol / o-dichlorobenzene, 1: 1 mixture at 25 ° C) according to ISO 1183.

Component B)

B / 1: styrene / isopropenyloxazoline copolymer (95/5% by weight) with an average molecular weight (M _W ) of 15 × 10 ⁴ g / mol (determined by GPC against polystyrene standard)
B / 2: styrene / acrylonitrile / isopropenyloxazoline copolymer (70/25/5% by weight) M _W : 4.9, 10 ⁴ g / mol
B / 1V: Polystyrene® 144 C from BASF AG
Components A) and B) were mixed in a twin-screw extruder at 250 ° C. and extruded into a water bath. After granulation and drying, test specimens were injected and tested on an injection molding machine.

The tensile test (modulus of elasticity, tensile strength and elongation at break) was according to ISO 527 and the Charpy notched impact strength according to ISO 179/1 eU determined.

Laser marking

The sample plates were made with a Nd-YAG laser at a wave length of 1064 nm, lamp current: 17 A with a writing speed at a speed of 750 mm / s.

Assessment of the quality of the font

The font is usually owned according to the four most important ones assessed: contrast, evenness, sharpness of contours and surface finish. The table below shows the contrast assessed with a Lumiancemeter according to the school grading system (1: very good to 6: very bad). The contrast is that Relationship between the luminance of the background and the writing.

The compositions of the molding compounds and the results of Measurements can be taken from the table.

Tabel

Claims (9)

1. A method for labeling moldings based on thermoplastic polymers A) or mixtures of such polymers with up to 70% by weight, based on the total weight of the components, other additives and processing aids, by means of high-energy radiation, characterized in that that a vinylaromatic polymer B) is used as an additive to improve the writability, which by incorporating at least one functional group selected from the series of carbonyl, carboxylic acid, acid anhydride, acid amide, acid imide, carboxylic acid ester, carbon oxylate, Amino, hydroxyl, epoxy, oxazoline, urethane, urea, lactam or halobenzyl groups has been modified. 2. The method according to claim 1, characterized in that one as thermoplastic polymers A) polyamides, polyesters or Polyoxymethylene uses. 3. The method according to claims 1 and 2, characterized net that the modified vinyl aromatic polymer B) in Men gen from 0.01 to 30 wt .-%, based on the total weight of the Components included in the mixture. 4. The method according to claims 1 to 3, characterized net that the functional compound in amounts from 0.1 to 10% by weight, based on the vinyl aromatic polymer B), ent hold is. 5. The method according to claims 1 to 4, characterized net that the functional compound from vinyloxazoline or Isopropenyloxazoline is built up. 6. The method according to claims 1 to 5, characterized net that the source of the high-energy radiation is a Nd: YAG laser with a wavelength of 1064 nm, which is after the deflection procedure works, is used. 7. The method according to claims 1 to 4, characterized net that the source of the high-energy radiation is a Nd: YAG laser with frequency doubling with a wavelength of 532 nm is used. 8. The method according to claims 1 to 4, characterized draws in as the source of high-energy radiation Excimer laser is used after the mask shot procedure works. 9. Labeled moldings, semi-finished products and finished parts are obtained Lich according to the method according to claims 1 to 8.