Polyurethanes are formed by essentially polymerizing diisocyanates with diols or polyols. Polyurethane foam is generated by adding water to the reaction mixture or using a blowing gas. Furthermore, stabilizers and activators such as for example amines, silicones and tin compounds are added to the reactants prior to the polymerization. The polymerization proceeds at elevated temperatures in the presence of highly reactive compounds and intermediates. To produce colored polyurethanes, the diol or polyol component may have added to it, before the polymerization, dyes which contain at least two hydroxyl groups, so that the dye can be covalently incorporated in the polymer chains during the polymerization without chain termination taking place as a result. The dye used must not affect the mechanical properties of the polyurethane. When the dye used is a solid material, it is advantageously dissolved in a solvent beforehand or used as a dye dispersion in a polyol for example. Dyes of this kind are known and are described in DE2259435 and DE2357933.

The solubility or dispersibility of the dye used can be significantly influenced through the choice of suitable substituents. The solubility or dispersibility can be improved through the choice of suitable side chains such that the use of solvent or dispersant matrix can be greatly reduced or even omitted entirely. Examples thereof are to be found in the documents WO2005000913, US2004250357 and US2004254335. When polyurethane foams are produced, some dyes affect foam structure and hence foam mechanical properties, so that the colored foam has different mechanical properties than the uncolored foam, and that is undesirable. The actually available suitable dyes for producing colored polyurethane foam do not allow coverage of every desired region in color space. There is therefore a need for dyes which have the properties mentioned and thus are useful for the coloration of polyurethane. The present invention provides dyes of formula (I)

where

R ¹ , R ² and R ³ each independently represent hydrogen, (CrC ₄ )-alkyl or

(CrC ₄ )-alkoxy;

R ^a , R ^b , R ^c and R ^d each independently represent hydrogen or methyl and have identical or different meanings within a molecule of formula (I), while when R ^a , R ^b , R ^c and R ^d have different meanings within a molecule of formula (I), these different meanings are randomly distributed or regions of respectively identical meanings follow each other; n and m each independently represent a number from 1 to 20;

A represents vinyl or a group -CH ₂ CH ₂ NR ⁴ R ⁵ ; and

R ⁴ and R ⁵ each independently represent (CrC ₄ )-alkyl; (CrC ₄ )-alkyl substituted by hydroxyl or (CrC ₄ )-alkoxy, or combine with the nitrogen atom to which they are attached to form a morpholine ring.

In the abovementioned definitions, alkyl groups may be straight-chain or branched and represent for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or tert- butyl. The same logic applies to alkoxy groups.

Preferably R ¹ , R ² and R ³ each independently represent hydrogen, methyl, ethyl, methoxy or ethoxy.

Preferably R ⁴ and R ⁵ each represent hydroxyl-, methoxy- or ethoxy-substituted ethyl or propyl.

Preferably n and m each independently represent a number from 5 to 18.

Preferred dyes of formula (I) conform to formula (Ia)

where A, R ¹ to R ³ , R ^a to R ^d , n and m are each as defined above. Examples of compounds of formula (Ia) conform to formulae (Ia1) to (IaIO)

(Ia1)

)

(Ia4) (Ia9)

The dyes of formula (I) according to the present invention are obtainable for example by a compound of formula (II)

where R ¹ , R ² and A are each as defined above, being diazotized and coupled onto a compound of formula (III)

where R ³ , R ^a to R ^d , m and n are each as defined above.

Diazotization and coupling may be effected by following the methods described in the literature and known to one skilled in the art.

Following their preparation, the dyes of formula (I) can be isolated by extraction and evaporation, or they can be used without further workup.

The dyes of formula (I) according to the present invention can be used directly for polymer coloration, or they are subjected to a finishing operation, i.e., converted into a saleable dye preparation. Finishing can be effected proceeding from a single dye or from a mixture of a plurality of dyes and also from mixtures with other dye classes such as for example pigments or solvent dyes, with or without assistance of auxiliaries, such as surface modifiers and dispersants, by dispersing, suspending or dissolving in a liquid or solid carrier material and also, if appropriate, standardizing to a desired color strength and a desired hue and, if appropriate, drying the preparation thus obtained.

Dye preparations comprising dyes of formula (I) may also include auxiliaries to modify their viscosity or flowability.

Suitable auxiliaries of this kind are described for example in US 6,605,126 and are, in particular, auxiliaries which, under the particular conditions, are themselves capable of polymer formation. Preferred examples are ethylene glycols, propylene glycols, polyether polyols, polyester polyols, lactones and carbonic esters. Caprolactone, butyrolactone and propylene carbonate are very particularly preferred.

The present invention accordingly also provides dye preparations comprising one or more dyes of formula (I) and also dye preparations comprising one or more dyes of formula (I) and one or more auxiliaries to modify viscosity/flowability. The latter dye preparations preferably comprise one or more dyes of formula (I) in amounts of 50% to 99% by weight and one or more auxiliaries to modify viscosity/flowability in amounts of 1% to 50% by weight, all based on the dye preparation.

The invention further provides for the use of the dyes of formula (I) according to the present invention for coloring a polymer. A possible procedure of this use is for the dye to be metered into the polymer or the reaction mixture during the polymerization, or to be admixed with one of the starting materials before the polymerization. Compounds of formula (I) are preferably used for coloring polyurethane by the compounds of the present invention either being added during the polymerization of diol/polyol and isocyanate or being added to one of the starting materials before the polymerization. For example, the dye of formula (I) according to the present invention can be admixed to a polyether polyol or to a polyester polyol and this preparation can then be used for the polymerization with a diisocyanate. It is customary to use the abovementioned stabilizers, activators or catalysts in the polymerization. Polyurethane foam is produced according to the same principle, the foam being produced by the addition of blowing gas or by the addition of water, leading to the formation of carbon dioxide blowing gas, to the diol/polyol component or to the reaction mixture of the polymerization.

Using the dyes of formula (I) according to the present invention it is thus possible to produce colored polyurethane foams having good fastnesses.

The processes described above polymerize the dyes of formula (I) according to the present invention into the polymer scaffold. But the dyes of formula (I) according to the present invention are also suitable for coloring polymers without a chemical bond having to be formed with the polymer scaffold.

For this purpose, they can be used in the processes known for the mass coloration of polymers, in which case they are used in particular in the form of masterbatches or solutions or in the form of the preparations described above.

To achieve good bleed fastnesses for the colored polymer, it is preferable to use dyes of sufficiently high molar mass.

The dyes of formula (I) have advantages in bleed or migration fastness over the commercially available solvent dyes in the polymer mass coloration of polyolefins in particular. These advantages come into effect in the coloration of polypropylene, polypropylene-co-polymers and polypropylene blends.

The examples hereinbelow serve to elucidate the invention without restricting the invention to these examples. Parts and percentages are by weight, unless otherwise stated. Parts by weight relate to parts by volume as the kilogram to the liter.

Example 1

388.7 g of a compound of formula (Ma)

(94.5% purity) are diazotized in dilute aqueous hydrochloric acid with 5N NaNO ₂ solution and then metered during 30 minutes at 20 ⁰ C into an aqueous solution, acidified with hydrochloric acid, of 1007.4 g of the compound of formula (III) where R ³ , R ^a and R ^c each represent hydrogen and R ^b and R ^d each represent methyl and the sum total of n and m is 13. Then, the pH is adjusted to 3.0 - 3.5 by a total of 244.0 g of sodium carbonate being sprinkled in. After subsequent stirring at room temperature for one hour, the reaction solution is warmed to 35°C and adjusted to pH 11.5 during 2 h by metered addition of altogether 200 ml of 20% NaOH solution. After the reaction has ended, the pH is brought back down to pH 7.0 - 7.5 with dilute hydrochloric acid. The precipitated dye is separated from the aqueous phase, washed twice with water and dried at 80 ⁰ C under reduced pressure to leave 1123 g of the dye (Ia1).

Example 2

Example 1 is repeated except that the reaction solution, after adjustment to pH

3.0 - 3.5, is admixed with 143.3 g of bis(2-methoxyethyl)amine before the rest of the procedure is carried out similarly to example 1. 1185.5 g of the dye (Ia2) are obtained.

Example 3

Example 1 is repeated except that 1705.8 g of the compound of formula (III) where R ³ represents methyl and in a first region R ^b and R ^d each represent methyl and R ^a and R ^c each represent hydrogen with the sum total of n and m being = 20 and in a second region R ^a to R ^d each represent hydrogen with the sum total of n and m being = 7, are added by metered addition. 1772.7 g of the dye (Ia4) are obtained.

Example 4

Example 2 is repeated using the compound of formula (III) from example 3. 1960.1 g of the dye (Ia5) are obtained.

Example 5

Example 2 is repeated using 143.3 g of bis(2-hydroxypropyl)amine and the compound of formula (III) from example 3. 1720.0 g of the dye (Ia7) are obtained.

Example 6

Example 2 is repeated using 93.7 g of morpholine. 1184.3 g of the dye (Ia8) are obtained. Example 7

Example 2 is repeated using 139.1 g of di-n-butylamine. 1218.6 g of the dye (Ia9) are obtained.

Example 8

Example 2 is repeated using 78.7 g of diethylamine. 1123.4 g of the dye (IaIO) are obtained.