The use of dyes of a wide variety of classes for the mass-colouring of synthetic materials is known. It has been shown, however, that not all synthetic materials can be coloured with satisfactory results with conventional dyes. Such"critical"synthetic materials also include materials based on terpolymers of acrylonitrile, butadiene and styrene which, owing to the very high temperatures that occur during processing and the heterogeneous structure, make specific demands of the dyes used. There is therefore a need for dyes with which such terpolymers (referred to hereinbelow as ABS terpolymers) can be mass-coloured in brilliant colour shades that are light-fast and fast to high temperatures.

It has now been found, surprisingly, that the naphtholactam dyes used in the method according to the invention meet the criteria given above to a considerable degree.

The present invention accordingly relates to a method of mass-colouring synthetic materials based on terpolymers of acrylonitrile, butadiene and styrene (ABS terpolymers), which comprises using at least one dye of formula wherein R, is hydrogen, halogen, alkoxy, aryloxy, alkylthio or arylthio, R2 is hydrogen, a carboxylic acid group or a carboxylic acid ester group, R3 is hydrogen, halogen, alkoxy, aryloxy, alkylthio, arylthio, a carboxylic acid group or a carboxylic acid ester group, and W is a radical of formula wherein R4, Re and Rn are each independently of the others hydrogen, alkyl, alkoxy, aryloxy, alkylthio or arylthio, R5, R7 and R10 are each independently of the others hydrogen, alkoxy, aryloxy, alkylthio, arylthio, a carboxylic acid group or a carboxylic acid ester group, R6 and Rg are each independently of the other cyano, -CONR12R13 or -SO2R14, wherein R12 and Pis are each independently of the other hydrogen or C1-C4alkyl and Ri4 is C1-C4alkyl, and X is -NH-, -O- or -S-, or R5 and R5'together form a phenyl or naphthyl radical.

R4, R8 and Rn as a ! ky) are each independently of the others preferably C1-C4alkyl, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl.

R12, R, 3 and R14 as C-C4alkyl are each independently of the others methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl.

R1, R3, R4, R5, R7, R8, Rio and R"as alkoxy are each independently of the others preferably C1-C4alkoxy, such as methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy or tert-butoxy, it being possible for the carbon chain in alkoxy to be interrupted one or more times by oxygen.

Ri, R3, R4, R5, R7, R8, Rio and RI, as alkylthio are each independently of the others preferably C,-C4alkylthio, for example methylthio, ethylthio, propylthio or butylthio.

Ri, R3, R4, R5, R7, R8, Rio and Rn as arytoxy are each independently of the others preferably C6-C12aryloxy, for example phenoxy or naphthyloxy.

Ri, R3, R4, R5, R7, R8, Rio and R"as arylthio are each independently of the others preferably C6-C12arylthio, for example phenylthio or naphthylthio.

The phenyl radicals in phenoxy can be unsubstituted or substituted by methyl, chlorine, C1-C4alkylthio and/or by arylthio.

The naphthyl radicals in naphthyloxy can be unsubstituted or substituted by methyl, chlorine, C1-C4alkylthio and/or by arylthio.

Halogen is, for example, chlorine or iodine and preferably bromine.

A carboxylic acid group is to be understood as being a- (CH2) n-COOH radical wherein n is a number from 0 to 3. n is preferably 0.

A carboxylic acid ester group is preferably a-(CH2)n-COOC1-6alkyl radical wherein n is a number from 0 to 3. n is preferably 0.

C1-C6Alkyl is, for example, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert- butyl, pentyl or hexyl.

Ri is preferably hydrogen, halogen or C1-C4alkylthio.

R2 is preferably hydrogen, -COOH or -COOC1-C6alkyl.

R3 is preferably hydrogen, -COOH or -COOC1-C6alkyl.

R4 is preferably hydrogen, C,-C4alkyl, C,-C4alkoxy, C,-C4alkylthio, C6-C, 2aryloxy or Ce-Cis- arylthio.

R5 is preferably hydrogen,-COOH,-COOC-C6alkyl, C1-C4alkyl, C1-C4alkoxy, C,-C4alkylthio, C6-C12aryloxy or C6-C, 2arylthio.

R6 is preferably cyano.

Rg is preferably cyano.

X is preferably-O-and-S-.

For the method according to the invention, preference is given to the dyes of formula wherein Ri2 is hydrogen, a carboxylic acid group or a carboxylic acid ester group, R13 is hydrogen or C6-C12arylthio, Ri4 is a carboxylic acid group or a carboxylic acid ester group, and R, 5 and R16 are each independently of the other hydrogen, C,-C4alkoxy, C6-C, 2aryloxy, C,-C4alkylthio or C6-C12arylthio, and of formula wherein R17 is hydrogen, a carboxylic acid group or a carboxylic acid ester group, RIB is hydrogen or halogen, Rig is hydrogen, R20 is cyano, R2, is hydrogen or C1-C4alkyl, R22 is a carboxylic acid group or a carboxylic acid ester group, and X is-O-or-S-.

For the method according to the invention, special preference is given to the dyes of formulae The dyes of formula (1) used in accordance with the invention are known, for example, from DE-A-2 736 914, DE-A-2 607 869, DE-A-2 724 566 and DE-A-2 724 567 or can be prepared according to generally known methods.

The dyes of formula (1) used in accordance with the invention are prepared, for example, by condensing a naphtholactam compound of formula wherein Ri, R2and R3 are as defined for formula (1), in the presence of an acid condensation agent, preferably phosphorus oxychloride, with a methylene-active compound of formula wherein R6, R7, R8 and X are as defined for formula (3), and Rg, Rio and R1, are as defined for formula (4).

The compounds of formulae (50) to (52) are known or can be prepared according to generally known methods.

The present invention relates also to the use of the dyes of formula (1) in the production of coloured plastics or polymeric colour particles, which comprises mixing together a high molecular weight organic material, which consists wholly or predominantly of ABS terpolymers or comprises ABS terpolymers, and a tinctorially effective amount of at least one dye of formula (1).

The colouring of such high molecular weight organic substances with the dye of formula (1) is carried out, for example, by mixing such a dye into those substrates using roll mills, mixing apparatus or grinding apparatus, with the result that the dye is dissolved or finely dispersed in the high molecular weight material. The high molecular weight organic material with the admixed dye is then processed using processes known per se, for example calendering, compression moulding, extrusion, coating, spinning, casting or injection moulding, whereby the coloured material acquires its final form. It is also possible for the admixing of the dye to be carried out immediately prior to the actual processing step, for example by continuously feeding a solid, for example pulverulent, dye and, at the same time, a granulated or pulverulent high molecular weight organic material, and optionally also additional ingredients, e. g. additives, directly into the intake zone of an extruder, where mixing takes place just before processing. In general, however, it is preferable for the dye to be mixed into the high molecular weight organic material beforehand, because more even coloration of the substrates can be obtained.

In order to produce non-rigid moulding or to reduce their brittleness, it is often desirable to incorporate so-called plasticisers into the high molecular weight compounds prior to shaping.

There may be used as plasticisers, for example, esters of phosphoric acid, phthalic acid or sebacic acid. In the method according to the invention the plasticisers may be incorporated into the polymers before or after the incorporation of the colorant. It is also possible, in order to achieve different shades of colour, to add to the high molecular weight organic materials, in addition to the dye of formula (1), also further dyes, pigments or other colorants in any desired amounts, optionally together with further additives, e. g. fillers or siccatives.

Preference is given to the colouring of thermoplastic plastics, especially in the form of fibres or mouldings.

The ABS terpolymer to be coloured comprises repeating monomer units of the formulae which may be linked to one another randomly, in an alternating manner or in the form of block or graft polymers.

The dyes used in accordance with the invention impart to the mentioned materials tinctorially strong, level red or orange colour shades having very good in-use fastness properties, especially good light fastness and good thermostability.

The following Examples serve to illustrate the invention. Unless otherwise indicated, the parts are parts by weight and the percentages are percentages by weight. The temperatures are given in degrees Celsius. The relationship between parts by weight and parts by volume is the same as that between grams and cubic centimetres.

Example 1 : 1200.00 g of an acrylamide-butadiene-styrene terpolymer (ABS) (Terluran 877M from BASF) are mixed homogeneously with 2.4 g of the dye of formula in a"roller rack"mixing apparatus for 15 minutes at 60 revolutions per minute.

The homogeneous mixture is extruded in an extruder (twin screw 25 mm from Collin, D-85560 Ebersberg) with 6 heating zones at a maximum temperature of 200°C, cooled with water, granulated in a granulator (Scheer, Stuttgart) and then dried in a granule drier (Turb Etuve TE 25 from MAPAG AG, CH-3001 Bern) for 4 hours at 60°C.

The resulting yellowish-red-coloured ABS granules are stable to high temperatures and have good allround fastness properties, especially very good light fastness and high-temperature light fastness properties.

Example 2: By following the procedure of Example 1 but using, instead of 2.4 g of the dye of formula (9), the same amount of one of the dyes of formulae (10) to (28), there are likewise obtained coloured ABS granules which are stable to high temperatures and have good allround fastness properties, especially very good light fastness and high-temperature light fastness properties.

Example 3: 1200.00 g of an acrylamide-butadiene-styrene terpolymer (ABS) (Terluran 877M from BASF) are mixed homogeneously with 2.4 g of the dye of formula and 12.0 g of TiO2 (Kronos 2220) in a"roller rack"mixing apparatus for 15 minutes at 60 revolutions per minute.

The homogenous mixture is extruded in an extruder (twin screw 25 mm from Collin, D-85560 Ebersberg) with 6 heating zones at a maximum temperature of 200°C, cooled with water, granulated in a granulator (Scheer, Stuttgart) and then dried in a granule drier (Turb Etuve TE 25 from MAPAG AG, CH-3001 Bern) for 4 hours at 60°C.

The resulting orange-to yellowish-red-coloured ABS granules are stable to high temperatures and have good allround fastness properties, especially very good light fastness and high-temperature light fastness properties.

Example 4: By following the procedure of Example 3 but using, instead of 2.4 g of the dye of formula (28), the same amount of one of the dyes of formulae (9) to (27), there are likewise obtained coloured ABS granules which are stable to high temperatures and have good allround fastness properties, especially very good light fastness and high-temperature light fastness properties.