DE102016213372A1 - NIR absorber Additives for the laser beam welding of plastics - Google Patents

Abstract

There are described 1,3-quadrains of the general formula (I) with 2,3-dihydro-1H-perimidinyl-wing groups and their use as additives for the production of laser-weldable thermoplastic polymer materials.

Description

There are described 1,3-quadrains of the general formula (I) with 2,3-dihydro-1H-perimidinyl-wing groups and their use as additives for the production of laser-weldable thermoplastic polymer materials. The invention particularly relates to organic NIR absorbers having an absorption maximum of 808 nm ± 20 nm for the production of laser-weldable thermoplastic polymer materials. The NIR absorbers have a high temperature stability and can be introduced into a polymer by means of extrusion.

State of the art

The laser beam welding of plastics or polymers has been established since about the mid-1990s as a material processing process. One of the advantages over conventional techniques, e.g. IR welding, is the high precision with which plastic parts can be joined together within a very short time, even with demanding geometries. Laser beam welding is used here, for example, for products in the automotive industry, in aviation technology and in medical technology, as well as for electronic devices and household appliances.

In the meantime, various embodiments have been developed for laser beam welding.

When Laserstrahlstumpfschweißen example, two joining partners are connected by a weld. The laser beam is absorbed by both joining partners and the introduced energy is converted into heat, which leads to melting along the joining area. As the depth of penetration of the laser beam increases, the intensity of the laser beam from the laser beam entrance side to the laser beam exit side decreases due to the increased absorption by the joining material. This leads to an asymmetrical temperature profile along the joint area - and thus also a corresponding strength profile.

In laser beam welding or overlap welding, two materials to be bonded are superimposed. The upper material is permeable to the laser beam. The underlying material absorbs the laser energy and converts it into heat, which leads to a symmetrical melting process between the joining partners and finally to a firm connection of the two materials.

A first technical possibility for near infrared laser radiation welding (NIR), for example, was Nd: YAG solid-state lasers (1064 nm) and fiber lasers (a special form of solid-state lasers), which however are higher in acquisition and maintenance costs , Therefore, over 90% of applications are typically performed with less expensive diode lasers.

Commercially available diode lasers usually have the emission range of 750 nm to 2000 nm. In order to achieve acceptable welding processing times, their output power should preferably be greater than 10 watts. This is achieved, for example, by diode lasers comprising GaAs semiconductor material which have an emission range of 750 nm to 1100 nm. In the meantime, three wavelengths have become established for various applications, namely with an emission maximum at 780 nm (eg CD player and burner), 808 nm (pumping of Nd: YAG solid-state lasers) and 980 nm (pumping of erbium-doped fiber amplifiers) ,

For a successful welding of plastics, as is apparent from the above statements, a certain absorption of the laser beam in the material to be connected or required to be provided.

Typically, regardless of their content of additives, polymers absorb in the mid-IR range (4000 cm ^-1 - 400 cm ^-1 ), so that thin films can be welded to a CO ₂ laser. Thicker films usually can not be welded with it, since the laser beam no longer penetrates to the second film or at higher intensity of the laser beam, the upper film would be thermally destroyed.

Therefore, in laser beam welding, the upper film is preferably transparent to the laser beam used. In principle, the near IR range from 780 nm to 1100 nm is suitable for this purpose.

The absorption of the laser radiation from the polymer material can be achieved alongside or in addition by additives (absorbers). Dyes and organic or inorganic pigments can be used as additives. Initially, only carbon black was available as an absorber, which of course limited the applicability of the process to dark-colored plastics.

Also in the field of inorganic chemistry comes a series of absorbers that can be used as additives for the laser welding of plastics. The DE 202004003362 discloses, for example, indium tin oxide (ITO), antimony tin oxide (ATO) and doped indium and antimony tin oxides, which are suitable for producing highly transparent, laser-markable or weldable plastic materials. In the WO 002010046285 are called compounds of tungsten, z. Alkali metal tungstates (tungsten bronze) and tungsten oxides of different stoichiometric composition for use with numerous polymeric materials. Boron-based IR absorbers, in particular lanthanum hexaboride, are disclosed in US Pat WO 002006029677 disclosed. In DE 102005035914 are called metal phosphates and phosphites, especially copper hydroxide phosphate (KHP), which has almost the same high absorption capacity as carbon black, but hardly affects the intrinsic color of the polymer matrix. The listed inorganic compounds are effective NIR or IR absorbers, but toxicologically partially unobjectionable, so that their applicability is limited.

In addition, as a further point, in particular many transparent polymers contain other nanoscale additives which absorb in the range between 900 nm and 1200 nm, so that in these cases the optically transparent polymer is no longer permeable to laser beams of this range. For the choice of the emission wavelength of the laser, however, it is advantageous that in many polymers there is a gap around 800 nm largely independent of additives, in which the transmission reaches high values, so that, for example, an 808 nm diode can be used for laser beam welding.

Only with the absorbers Lumogen ^® IR 765 and IR 788 by BASF AG, an improved laser welding of colored or transparent plastics has been possible. The absorbers of the Lumogen ^® series fulfill the criteria as additives for laser-weldable plastics very well. They are organic compounds and characterized in that they have no absorption in the visible range, do not affect the mechanical properties of the polymer and are not toxic. For different laser wavelengths corresponding products are available. Their production is very costly.

An important property of absorbers as additives, which is not easy to realize in the case of organic compounds, is a high temperature stability of ideally ≥ 300 ° C., since the absorbers are subjected to several times high temperatures up to the actual welding process. For example, these are on the one hand the conditions during extrusion in the production of masterbatches or compounding and on the other hand, the temperatures during injection molding for the production of the actual plastic moldings. During these processes, no decomposition of the absorber may occur, so that they are available during later laser welding.

Lumogen^® IR 788 The -Lumogen ^® IR has for example 788 a decomposition temperature of about 350 ° C and is chemically seen a Quaterrylentetracarbonsaurediimid.

-Lumogen ^® IR 788

The synthesis of quaterrylenetetracarboxylic acid diimides is, for example, in Quante, H., Müllen, K .; Angew. Chem., 1995, 107 (12), 1487 outlined. A special feature of these compounds is that they are present either as pigments or as soluble absorbers, depending on substituents. However, the synthesis is expensive and therefore expensive, and the analytical characterization of intermediate and end products is sometimes difficult because of their poor solubility.

The synthesis, as reported by Quante and Müllen, is based on half-sidedly functionalized perylene derivatives. After monobrominating, a Yamamoto coupling to biperylenyl compounds takes place by means of a nickel catalyst. The final cyclization to quaterrylene is carried out in a KOH melt with the addition of an oxidizing agent. The individual reaction steps are already very well optimized, so that it will probably not be possible to further reduce the cost of synthesis.

Another class of compounds which show intensive absorption in the NIR are condensation products of squaric acid with substituted anilines (2) and 2,3-dihydro-1H-perimidines (3):

Compounds of this type are described in the literature, eg in Bello, KA, Corns, SN, Griffith, J .; J. Chem. Soc., Chem. Commun., 1993, 452 , With the substituted anilines, absorption maxima between 640 and 708 nm are indicated in the cited literature. The desired absorption range of 808 nm ± 20 nm is reached only with the products 3, in which the 2,3-dihydro-1H-perimidinyl group contributes to a bathochromic shift of the absorption maximum.

The high decomposition point of squaric acid at 293 ° C suggests that the condensation products of squaric acid, the 1,3-quadraine, could also be thermally stable products.

A literature search found two different linking possibilities of 2,3-dihydro-1H-perimidin with the central four-membered ring in 1,3-quadraines. Once the link can be made in 6-position (structure 3) and on the other in the 4-position (structure 4):

In addition, there is no clear analytical evidence in the literature that allows for unambiguous assignment, which is also difficult, since it is often almost insoluble compounds. Recently, it was first demonstrated on a sufficiently soluble 1,3-quadrina (structure 4, R ¹ = R ² = CH ₂ O (CO) C ₅ H ₁₁ ) that a linkage of the 2,3-dihydro-1H-perimidine with the Squaric acid is preferably in the 4-position ( Mistol, J., Ernst, S., Keil, D., Hennig, L .; Dyes and Pigments, 2015, 118, 58 ). The investigated compound decomposes at 236 ° C. However, better solubility in these compounds is often paid for by a poorer thermal stability.

There is therefore a need for temperature-stable additives for laser beam welding, which have a good absorption in the near infrared range. In particular, it is an object of the present invention to produce novel organic absorbers which have a decomposition temperature of ≥ 300 ° C. and an absorption of 808 nm which is sufficient for the use of diode lasers, and are free of halogens and heavy metals. The absorbers shall preferably be readily soluble in a polymer with the lowest possible tendency to aggregate, and less expensive than the representatives of -Lumogen ^® series.

This problem is solved by synthesis of symmetrical 1,3-quadraines with 2,3-dihydro-1H-perimidinyl-wing groups of the general formula (I).

The inventors have found that certain squaric acid derivatives are temperature stable compounds which have an absorption in the range of 808 nm and can be prepared easily and inexpensively. By varying the substituents R ¹ and R ² , one can arrive at a suitable absorber for the laser beam welding. Opposite Lumogen ^® IR 788 show 1,3-Quad Raine the invention additionally has the advantage that the absorbance per gram of absorber is about 2 to 2.5 fold is usually so high.

wobei R1 und R2 gleich oder verschieden sind und ausgewählt sind aus einem Wasserstoffrest, einem substituierten oder unsubstituierten Alkylrest mit 1 bis 20 C-Atomen, einem substituierten oder unsubstituierten Alkenyl und/oder Alkinylrest mit 2 bis 20 C-Atomen, einem substituierten oder unsubstituierten Arylrest mit 6 bis 30 C-Atomen, und einem substituierten oder unsubstituierten Alkylarylrest oder Arylalkylrest mit 7 bis 30 C-Atomen, wobei mindestens eines von R1 und R2 ausgewählt ist aus einem substituierten oder unsubstituierten Arylrest mit 6 bis 30 C-Atomen und einem substituierten oder unsubstituierten Alkylarylrest oder Arylalkylrest mit 7 bis 30 C-Atomen;
oder wobei R1 und R2 einen substituierten oder unsubstituierten Cycloalkylidenrest mit 3 bis 20 C-Atomen darstellen.In a first aspect, the present invention relates to 1,3-quadraines of the general formula (I)

wherein R 1 and R 2 are the same or different and are selected from a hydrogen radical, a substituted or unsubstituted alkyl radical having 1 to 20 C atoms, a substituted or unsubstituted alkenyl and / or alkynyl radical having 2 to 20 C atoms, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms, and a substituted or unsubstituted alkylaryl or arylalkyl having 7 to 30 carbon atoms, wherein at least one of R 1 and R 2 is selected from a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and a substituted or unsubstituted alkylaryl or arylalkyl having 7 to 30 carbon atoms;
or wherein R 1 and R 2 represent a substituted or unsubstituted cycloalkylidene radical having 3 to 20 C atoms.

In a further aspect, the present invention relates to the use of such quadrains as an additive for the laser beam welding of plastics.

In addition, the invention relates to a method for laser beam welding of plastics, wherein at least one 1.3-quadrine of the general formula (I) is introduced according to the first aspect of the invention in a polymer, the polymer is solidified into a plastic, and the plastic produced with at least one further plastic part is connected by laser beam welding.

Further aspects of the present invention can be found in the dependent claims and the detailed description.

Description of the figures

The accompanying drawings are intended to illustrate embodiments of the present invention and to provide a further understanding thereof. In the context of the description, they serve to explain concepts and principles of the invention. Other embodiments and many of the stated advantages will become apparent with reference to the drawings. The elements of the drawings are not necessarily to scale. Identical, functionally identical and identically acting elements, features and components are in the figures of the drawings, unless otherwise stated, each provided with the same reference numerals.

1 shows measurement results of an absorption measurement of the compound Q11 in DMF or in PET.

Detailed description of the invention

In the context of the invention, technical and scientific terms, unless otherwise defined, have the same meaning as commonly understood by one of ordinary skill in the art.

In the context of the invention, the near infrared range is understood to be the wavelength range from 780 nm to 3 μm.

wobei R¹ und R² gleich oder verschieden sind und ausgewählt sind aus einem Wasserstoffrest, einem substituierten oder unsubstituierten Alkylrest mit 1 bis 20 C-Atomen, einem substituierten oder unsubstituierten Alkenyl und/oder Alkinylrest mit 2 bis 20 C-Atomen, einem substituierten oder unsubstituierten Arylrest mit 6 bis 30 C-Atomen, und einem substituierten oder unsubstituierten Alkylarylrest oder Arylalkylrest mit 7 bis 30 C-Atomen, wobei mindestens eines von R¹ und R² ausgewählt ist aus einem substituierten oder unsubstituierten Arylrest mit 6 bis 30 C-Atomen und einem substituierten oder unsubstituierten Alkylarylrest oder Arylalkylrest mit 7 bis 30 C-Atomen;
oder wobei R¹ und R² einen substituierten oder unsubstituierten Cycloalkylidenrest mit 3 bis 20 C-Atomen darstellen. Gemäß bestimmten Ausführungsformen ist mindestens eines von R¹ und R² ausgewählt aus einem unsubstituierten Arylrest mit 6 bis 30 C-Atomen und einem unsubstituierten Alkylarylrest oder Arylalkylrest mit 7 bis 30 C-Atomen. Gemäß bestimmten Ausführungsformen weisen die 1,3-Quadraine mindestens einen aromatischen Rest in jeder Flügelgruppe auf. Durch einen Arylrest kann eine verbesserte Temperaturstabilität erzielt werden. Gemäß bestimmten Ausführungsformen ist R¹ und/oder R² ausgewählt aus C₆H₅, 4-CH₃-(C₆H₄), 4-CH₃O-(C₆H₄), 4-NC-(C₆H₄) und C₆H₅CH₂. Gemäß bestimmten Ausführungsformen ist R¹ CH₃ und R² ausgewählt aus C₆H₅, 4-CH₃-(C₆H₄), 4-CH₃O-(C₆H₄), 4-NC-(C₆H₄) und C₆H₅CH₂, bevorzugt C₆H₅, 4-CH₃-(C₆H₄), 4-CH₃O-(C₆H₄) und 4-NC-(C₆H₄). Gemäß bestimmten Ausführungsformen sind R¹ und R² C₆H₅CH₂.The invention relates in a first aspect to 1,3-quadraines of the general formula (I)

wherein R ¹ and R ^{2 are the} same or different and are selected from a hydrogen radical, a substituted or unsubstituted alkyl radical having 1 to 20 C atoms, a substituted or unsubstituted alkenyl and / or alkynyl radical having 2 to 20 C atoms, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms, and a substituted or unsubstituted alkylaryl radical or arylalkyl radical having 7 to 30 carbon atoms, wherein at least one of R ¹ and R ^{2 is} selected from a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and a substituted or unsubstituted alkylaryl or arylalkyl having 7 to 30 carbon atoms;
or wherein R ¹ and R ^{2 represent} a substituted or unsubstituted Cycloalkylidenrest having 3 to 20 carbon atoms. In certain embodiments, at least one of R ¹ and R ^{2 is} selected from an unsubstituted aryl group of 6 to 30 carbon atoms and an unsubstituted alkylaryl group or arylalkyl group of 7 to 30 carbon atoms. According to certain embodiments, the 1,3-quadraines have at least one aromatic radical in each wing group. By an aryl radical improved temperature stability can be achieved. In certain embodiments, R ¹ and / or R ^{2 is} selected from C ₆ H ₅ , 4-CH ₃ - (C ₆ H ₄ ), 4-CH ₃ O- (C ₆ H ₄ ), 4-NC- (C ₆ H ₄ ) and C ₆ H ₅ CH ₂ . In certain embodiments, R ^{1 is} CH ₃ and R ^{2 is} selected from C ₆ H ₅ , 4-CH ₃ - (C ₆ H ₄ ), 4-CH ₃ O- (C ₆ H ₄ ), 4 -NC- (C ₆ H ₄ ) and C ₆ H ₅ CH ₂ , preferably C ₆ H ₅ , 4-CH ₃ - (C ₆ H ₄ ), 4-CH ₃ O- (C ₆ H ₄ ) and 4-NC- (C ₆ H ₄ ). In certain embodiments, R ¹ and R ^{2 are} C ₆ H ₅ CH ₂ .

The substituents are not particularly limited in the respective radicals and may be, for example, halogen (especially F, Cl, Br and / or I), CN, CHO, COOH, nitro, nitroso, amino, hydroxy and / or or alkoxy groups having 1 to 20 carbon atoms, preferably 1 to 4 carbon atoms.

According to certain embodiments, the substituents in the respective substituted radicals are electron-donating groups, ie those which cause a + I effect, a positive inductive effect, in particular alkyl groups.

According to certain embodiments, R ¹ and R ^{2 represent} a substituted or unsubstituted cycloalkylidene radical having from 3 to 20 carbon atoms, eg a substituted or unsubstituted adamantanylidene radical, more preferably an unsubstituted cycloalkylidene radical having from 3 to 20 carbon atoms, especially an unsubstituted adamantanylidene radical. A preferred compound is 4- (2-adamantanylidene-1H-perimidin-3-ium-4 (2H) -ylidene) -2- (2-adamantanylidene-2,3-dihydro-1H-perimidin-4-yl) -3 -oxocyclobut-1-enolate.

The 1,3-quadrains according to the invention are characterized in particular embodiments by an absorption maximum of 808 nm ± 20 nm and thermal stability to at least 300 ° C.

The synthesis of the 1,3-quadrains according to the invention is not particularly limited and can be suitably carried out by conventional methods, for example via the intermediate of substituted 2,3-dihydro-1H-perimidimidines.

The synthesis of 2,3-dihydro-1H-perimidines, for example, in this case proceed according to known methods. For example, 1,8-diamino-naphthalene is condensed in alcohols such as ethanol or n-propanol with aliphatic open-chain or cyclic ketones or mixed aliphatic aromatic ketones in the presence of an acidic catalyst such as 4-toluenesulfonic acid or bismuth III chloride. The reaction mixture can then, for example, for about 2 h, held at reflux and then cooled, whereupon the corresponding formed substituted 2,3-dihydro-1H-perimidine crystallized. The particular product can then be e.g. be separated by filtration.

The synthesis of the 1,3-quadraine proceeds according to methods known from the literature. The isolated substituted 2,3-dihydro-1H-perimidines can be condensed with squaric acid, for example in a molar ratio of 2: 1. Examples of suitable solvents are mixtures of n-propanol and toluene or n-butanol and Toluene suitable, although other solvents are conceivable. For larger approaches, it is recommended to recirculate water by means of a water separator. For example, after a reaction time of 2-7 hours, the 1,3-quadrene precipitates out of the reaction mixture upon cooling, and / or can be obtained after distilling off the solvent.

wobei R¹ und R² gleich oder verschieden sind und ausgewählt sind aus einem Wasserstoffrest, einem substituierten oder unsubstituierten Alkylrest mit 1 bis 20 C-Atomen, einem substituierten oder unsubstituierten Alkenyl und/oder Alkinylrest mit 2 bis 20 C-Atomen, einem substituierten oder unsubstituierten Arylrest mit 6 bis 30 C-Atomen, und einem substituierten oder unsubstituierten Alkylarylrest oder Arylalkylrest mit 7 bis 30 C-Atomen, wobei mindestens eines von R¹ und R² ausgewählt ist aus einem substituierten oder unsubstituierten Arylrest mit 6 bis 30 C-Atomen und einem substituierten oder unsubstituierten Alkylarylrest oder Arylalkylrest mit 7 bis 30 C-Atomen;
oder wobei R¹ und R² einen substituierten oder unsubstituierten Cycloalkylidenrest mit 3 bis 20 C-Atomen darstellen,
als Additiv für das Laserstrahlschweißen von Kunststoffen.In a second aspect, the present invention relates to the use of a 1,3-quadramine of the general formula (I)

wherein R ¹ and R ^{2 are the} same or different and are selected from a hydrogen radical, a substituted or unsubstituted alkyl radical having 1 to 20 C atoms, a substituted or unsubstituted alkenyl and / or alkynyl radical having 2 to 20 C atoms, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms, and a substituted or unsubstituted alkylaryl radical or arylalkyl radical having 7 to 30 carbon atoms, wherein at least one of R ¹ and R ^{2 is} selected from a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and a substituted or unsubstituted alkylaryl or arylalkyl having 7 to 30 carbon atoms;
or where R ¹ and R ^{2 represent} a substituted or unsubstituted cycloalkylidene radical having 3 to 20 C atoms,
as an additive for the laser beam welding of plastics.

The plastic is not particularly limited, insofar as it is weldable, so in particular a thermoplastic.

The laser beam welding is not particularly limited and includes, for example, laser butt welding and / or laser beam welding. The corresponding welding parameters such as energy of the laser beam, welding time, etc. can be suitably adjusted, for example, depending on the area to be welded, the plastic to be welded, etc., suitably.

Moreover, the present invention relates to a method for laser beam welding of plastics, wherein at least one 1,3-quadrine of the general formula (I) according to the first aspect of the invention is introduced into a polymer, the polymer is solidified into a plastic, and the plastic produced is connected to at least one further plastic part by laser beam welding.

The plastic as well as the other plastic part are not particularly limited and may be the same or different, as long as the materials of the two parts are chemically and physically compatible and the melting temperatures sufficiently overlap, e.g. with the same plastics, as is possible with different ones, e.g. Polycarbonate (PC) and polybutylene terephthalate (PBT). Also, the laser is not particularly limited here. According to certain embodiments, the laser beam welding is performed at a wavelength between 780 and 850 nm, according to certain embodiments with a laser having an emission wavelength in the range of 808 nm ± 20 nm, e.g. about 808 nm. If necessary, the emission wavelength of the laser can also be further adjusted.

According to certain embodiments, the solidification of the polymer is carried out at a temperature of at least 280 ° C, preferably at least 300 ° C.

The incorporation of the at least one 1,3-quadriene of the general formula (I) according to the first aspect of the invention into a polymer is likewise not restricted and can be effected, for example, by mixing, application, extrusion, etc. According to certain embodiments, it is carried out by extrusion, in particular by parallel entry. However, extrusion after mixing is not excluded according to the invention.

The above embodiments, refinements and developments can, if appropriate, be combined with one another as desired. Further possible refinements, developments and implementations of the invention also include combinations of features of the invention which have not been explicitly mentioned above or described below with regard to the exemplary embodiments. In particular, the person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the present invention.

In the following, the invention will be described with reference to some embodiments, to which the invention is not limited.

Examples

example 1

Preparation of 4- (2-adamantanylidene-1H-perimidin-3-ium-4 (2H) -ylidene) -2- (2-adamantanylidene-2,3-dihydro-1H-perimidin-4-yl) -3-oxocyclobut -1-enolate (Example 11 in Table 1)

2-adamantan-2-ylidene-2,3-dihydro-1H-perimidine

39.55 g (0.25 mol) of 1,8-diamino-naphthalene, 37.56 g (0.25 mol) of 2-adamantanone and 4.76 g (10 mol%) of 4-toluenesulfonic acid monohydrate are in 500 ml of 99% ethanol for 1 - 2 hours with stirring at reflux. The mixture is then cooled to room temperature and the crystallized product is filtered off. Yield: 53.2 g (73% of theory), mp (fixed point) = 215-218 ° C.

4- (2-Adamantanyliden-1H-perimidine-3-ium-4 (2H) -ylidene) -2- (2-adamantanyliden-2,3-dihydro-1H-perimidine-4-yl) -3-oxocyclobut-1 enolate

43.56 g (0.15 mol) of 2-adamantan-2-ylidene-2,3-dihydro-1H-perimidine are mixed with 8.55 g (0, 075 mol) of squaric acid in a mixture of 150 ml of n-propanol and 75 ml of toluene heated to reflux for 5-7 hours. Resulting in the reaction of water is separated by means of a water separator. The reaction product is filtered off after cooling the batch to room temperature. Yield: 39.4 g (77% of theory).

Reference Example: Synthesis of 1,3-quadraines

The synthesis of the 1,3-quadraines given in Table 1 was carried out analogously to Example 1 via the intermediate stage of the preparation of substituted 2,3-dihydro-1H-perimidines, wherein the substituents of the substituted 2,3-dihydro-1H-perimidines produced the in Table 1 radicals R ¹ and R ² , which are prepared by reaction with corresponding ketones.

For the preparation of the substituted 2,3-dihydro-1H-perimidines, 1,8-diamino-naphthalene in alcohols such as ethanol or n-propanol with aliphatic open-chain or cyclic ketones or mixed aliphatic, aromatic ketones in the presence of an acid catalyst such as 4- Toluene sulfonic acid or bismuth III chloride condenses. The reaction mixture is then held for about 2 h, at reflux and then cooled, whereupon the formed 2,3-dihydro-1H-perimidine crystallized out. The respective product is separated by filtration.

The isolated 2,3-dihydro-1H-perimidines are then condensed with squaric acid in a molar ratio of 2: 1. The solvents used are mixtures of n-propanol and toluene or n-butanol and toluene. For larger approaches, it is recommended to recirculate water by means of a water separator. The 1,3-quadrene precipitates after a reaction time of 2-7 hours from the reaction mixture on cooling, or is obtained after distilling off the solvent.

The obtained 1,3-quadraines are purified and then their absorption spectra and their thermal properties are determined by absorption spectrometry after dissolution in dimethylformamide (DMF) or differential scanning calorimetry (DSC).

Absorption measurements were carried out with a Specord 250 UV-VIS spectrometer from Analytik Jena. To prepare the measurement solutions, about 0.2 mg of the respective 1,3-quadramine was dissolved in 50 ml of DMF and briefly treated in an ultrasound bath. The measurement solutions had a concentration of about 5 × 10 ^-6 mol / l. The measurement was carried out in each case in a 10 mm cuvette against pure DMF as reference in the range of 400 up to 1100 nm with a step size of 1.0 nm. The absorption maximum is the longest wavelength value in nm at which the curve has a maximum.

In addition, the compounds were calorimetrically measured and measured the decomposition point Zp with respect to the onsets and the peak. For this purpose, a sample amount of 2-4 mg was tested with the device DSC 822 from Mettler.

T_e = Onsettemperatur; T_p = PeaktemperaturThe results obtained for the maximum absorption wavelength λ _max and the onset temperature T _e and peak temperature T _p in the DSC are shown in Table 1. Table 1 Exemplified 1,3-quadrains of the general structural formula (I)

T _e = onset temperature; T _p = peak temperature

It is apparent from Table 1 that the desired target absorption range of 808 nm ± 20 nm is definitely met by the present compounds. The temperature stability is influenced by the substituents R ¹ and R ² . Pure alkyl substitution leads to a decomposition temperature well below 300 ° C. Alkylaryl substitution or aryl substitution already has a favorable effect on the decomposition temperature, even if the specification of ≥300 ° C. is barely reached.

The compounds 9 and 10 from the cyclic ketones cyclopentanone and cyclohexanone have a temperature stability which does not reach 300 ° C. In contrast, the tricyclic ketone 2-adamantanone gives a 1,3-quadrine which, with a decomposition temperature of 344 ° C., has the highest temperature stability among the compounds prepared. The reason for this is probably the extremely stable, diamond-like structure of the formally composed of four cyclohexane rings tricycle. This is also reflected in the fact that adamantane itself melts unusually high (mp = 270 ° C) compared to its constitutive isomeric compounds.

The solubility of product 11 (Q11) in a polymer was further investigated. For this purpose, on the one hand, the compound was dissolved in DMF and, on the other hand, co-extruded with polyethylene terephthalate (PET, 0.01% addition) to give a film.

The results of an absorbance measurement of both samples - analogous to the method described above - are in 1 shown. Therein, the spectra of the DMF solution and the PET film are compared with a 0.01% addition of the absorber, wherein the absorption A was plotted against the measurement wavelength λ. In the range 780 to 900 nm, both curves are almost identical. There is no broadening of the spectra in the polymer, as is often the case when the solubility is insufficient.

Comparative Example 1

Even with cyanine dyes, one can reach a target range of absorption around 808 nm very well. By means of the individual structural elements of the cyanine dye (wing groups, methine chain and counterion), the absorption maximum, extinction, stability and solubility can be influenced. Some cyanine dyes were tested for their suitability as additives for laser beam welding. By way of example, the following compounds, S 0094 and S 0985, which were originally designed for other applications, may be mentioned.

The decomposition temperatures for these compounds are 235 ° C. and 289 ° C. In both cases, no welding was possible in laser beam welding tests with polypropylene films. Even the thermally more stable compound S 0985 already changed during the extrusion, recognizable by discoloration at temperatures around 240 ° C.

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

• DE 202004003362 [0012]
• WO 002010046285 [0012]
• WO 002006029677 [0012]
• DE 102005035914 [0012]

Cited non-patent literature

• Quante, H., Müllen, K .; Angew. Chem., 1995, 107 (12), 1487 [0017]
• Bello, KA, Corns, SN, Griffith, J .; J. Chem. Soc., Chem. Commun., 1993, 452 [0020]
• Mistol, J., Ernst, S., Keil, D., Hennig, L .; Dyes and Pigments, 2015, 118, 58. [0023]

Claims (11)

1,3-quadraines of the general formula (I)

wherein R ¹ and R ^{2 are the} same or different and are selected from a hydrogen radical, a substituted or unsubstituted alkyl radical having 1 to 20 C atoms, a substituted or unsubstituted alkenyl and / or alkynyl radical having 2 to 20 C atoms, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms, and a substituted or unsubstituted alkylaryl radical or arylalkyl radical having 7 to 30 carbon atoms, wherein at least one of R ¹ and R ^{2 is} selected from a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and a substituted or unsubstituted alkylaryl or arylalkyl having 7 to 30 carbon atoms; or wherein R ¹ and R ^{2 represent} a substituted or unsubstituted Cycloalkylidenrest having 3 to 20 carbon atoms. 1,3-quadrains of the general formula (I) according to claim 1, wherein the substituents are electron-donating groups. 1.3-quadrains of the general formula (I) according to claim 1, wherein at least one of R ¹ and R ^{2 is} selected from an unsubstituted aryl radical having 6 to 30 carbon atoms and an unsubstituted alkylaryl or arylalkyl having 7 to 30 carbon atoms , 1.3-quadrains of the general formula (I) according to claim 1, wherein R ¹ and R ^{2 represent} an unsubstituted cycloalkylidene radical having 3 to 20 C atoms. 1,3-quadrains of the general formula (I) according to claim 4, wherein R ¹ and R ^{2 represent} an unsubstituted adamantanylidene radical. Use of a 1,3-quadrin of the general formula (I)

wherein R ¹ and R ^{2 are the} same or different and are selected from a hydrogen radical, a substituted or unsubstituted alkyl radical having 1 to 20 C atoms, a substituted or unsubstituted alkenyl and / or alkynyl radical having 2 to 20 C atoms, a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms, and a substituted or unsubstituted alkylaryl radical or arylalkyl radical having 7 to 30 carbon atoms, wherein at least one of R ¹ and R ^{2 is} selected from a substituted or unsubstituted aryl radical having 6 to 30 carbon atoms and a substituted or unsubstituted alkylaryl or arylalkyl having 7 to 30 carbon atoms; or wherein R ¹ and R ^{2 represent} a substituted or unsubstituted Cycloalkylidenrest having 3 to 20 carbon atoms, as an additive for the laser beam welding of plastics. A method for laser beam welding of plastics, wherein at least one 1,3-quadrine of the general formula (I) according to any one of claims 1 to 5 is introduced into a polymer, the polymer is solidified to a plastic, and the plastic produced with at least one further plastic part is connected by laser beam welding. The method of claim 7, wherein the laser beam welding is performed at a wavelength between 780 and 850 nm. The method of claim 8, wherein the laser beam welding is performed with a laser having an emission wavelength in the range of 808 nm ± 20 nm. A method according to any one of claims 7 to 9, wherein the solidification of the polymer is carried out at a temperature of at least 280 ° C. Method according to one of claims 7 to 10, wherein the introduction of the at least one 1,3-quadrine of the general formula (I) according to one of claims 1 to 5 in a polymer by extrusion takes place.

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