CA1084910A - Azo pigments and process for their production - Google Patents

Abstract

Abstract of the Disclosure Azo pigments of the formula wherein R represents an alkylsulphonyl, an aralkylsulphonyl or an arylsulphonyl group, an alkanoyl, a benzoyl, an alkanoyloxy, an aroyloxy group or the group -N=N-aryl, R2 represents a hydrogen atom, an alkyl group or a phenyl radical, X1 and X2, each independently of the other, represents a hydrogen or halogen atom, an alkyl, alkoxy, trifluoro-methyl or nitro group, Y represents a hydrogen or halogen atom, an alkyl, alkoxy or a phenoxy group, n is 1 or 2, Z represents the NH-group or a group of the formula -CONH- or

Description

`- 10~4910 The invention relates to valuable new azo pigments of the formula O= ~ ~ NHCOCU N--N ~ Xl (I) wherein R represents an alkylsulphonyl group of 1 to 4 caxbon atoms, an aralkylsulphonyl group or an arylsulphonyl group which is unsubstituted or substituted by halogen atoms, alkyl or alkoxy groups of 1 to 4 carbon atoms, an alkanoyl group of 2 to 6 carbon atoms or a benzoyl group which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups of 1 to 4 carbon atoms, an alkanoyloxy group of 2 to 6 carbon atoms, an aroyloxy group which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups of 1 to 4 carbon atoms, ~ or represents the group -N-N-aryl, the aryl moiety of which can be substituted by halogen at~ms, alkyl or alkoxy groups of 1 to 4 carbon atoms, alkanoylamino or ;~ alkoxycarbonyl groups of 2 to 6 carbon atoms, nitro, trifluoromethyl or carbamoyl gr~ ps, R2 represents a hydrogen atom, an alkyl group of 1 to 4 carbon atoms or a phenyl radical which is unsubstituted

- 2 _ .~
, . . . .. .
i . ~ . , , --` 10~4910 or substituted by halogen atoms or alkyl or alkoxy group.s of 1 to 4 carbon atoms, Xl and X2, each independently of the other, represents a hydrogen or halogen atom, an alkyl or alkoxy group of 1 to 4 carbon atoms, a trifluoromethyl or nitro group, Y reprcsents a hydrogen or halogen atom, an alkyl or alkoxy group of 1 to 4 carbon atoms or a phenoxy group, n is 1 or 2, Z represents the NH-group or a group of the formula H
-CONH- or -CcC-wherein R3 represents an alkyl group of 1 to 4 carbon atoms or a phenyl radical which is unsubstituted or substituted by halogen atoms or alkyl or aLkoxy groups of 1 ~o 4 carbon atom8.

Particularly preferred azo pigments are those of the fonnula - ~ 3 OzC ~ NHCO H-N= ~ X

\N yl X2 ~4 - , ' '. , ' ' ' ' .

4~10 wherein R, Xl and X2 are as defined in formula (I), Yl represents a hydrogen or chlorine a~om, a methyl, methoxy or ethoxy group, R4 represents a hydrogen atom or an alkyl group of 1 to 4 carbon atoms, and especially monoazo pigments of the formula Çl~3 ~1 ¢ l 02R5 N CO~H -N=N ~

wherein R4 and Yl are as defined above and R5 represènts an alkyl group of 1 to 2 carbon atams, a benzyl group or a phenyl group which is unsubstituted or sub~tituted by halogen . atoms ~ aDkyl or alkoxy groups o~ 1 to 4 carbon atoms.

Halogen substituents are in particular chlorine or bromine at~ms, preferably chlorine.

Alkyl group substituents are for example the methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl or tert-butyl group, preferably the methyl or ethyl group Alkoxy group substituents are for example methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy or tert-butoxy groups, r.
:' : , . . . . . . . :

.. . . . ~

~-~' 1~8 4910 especially the methoxy and ethoxy group.

Aryl r~dicals are for ex~llple naphthyl, especially phenyl, radicals.

Particularly prefe~red pig~ents are those of the formula o:~J NHCOC~I -N=N ~

~ wherein Y has the meaning previously given and R6 represents : a methyl or ethyl group, as well as those of the formula ~ NHCOCH-N--N~N=N~
O~C ~ 10CH3 Y \~X5 . ~

wherein X3 and X4 represent chlorine atoms or methyl or methoxy groups, and X5 represents a hydrogen or chlorine at or a methyl group, or those of the formula U COCH3 ~ CO ~ X6 ~ : . : . -. ., . . , ,., . ............ . :

- - :

wherein XG represents a hydrogen or chlorine at~m, a methyl or rnethoxy group.

The pigments of the present invention are obtained by coupling a diazo compound of an amine of ~he formula R

with an acetoacetylarylide of the formula o ~ ucocH2cocH3 ;:
The diazo component is preferably an amine of the formula H2N ~) wherein R5 has the meaning previously given, .

10~49~0 Examples of diazo components are:
2_ethylsulphonyl-5-t:rifllloromethylaniline 2-benzylsulphonyl-5-trifluoromethylanilin2 2-phenylsulphonyl-5-trifluoromethylaniline 2_methylsulphonyl-4-nitroaniline 2_ethylsulphonyl-4-nitroaniline 4-amino-3-nitro-azobenzene 4-amino-2,5-dimethyl-azobenzene 4-amino-2,5-d~methyl-4'-chloro-azobenzene 4-amino-2,5-dimethyl-4'-methoxy-azobenzene 4-amino-2,5-dimethyl-4'-methyl-azobenzene 4-amino-2,5-dimethyl-3'-trifluoromethyl-azobenzene 4-amino-2,5-dimethyl-4'-carb~methoxy-azobenzene 4-amino-2,5-dimethoxy-azobenzene 2-methyl-5-phenylsulphonyl-aniline 2_methoxy 5-phenylsulphonyl-aniline 2-methoxy-5-para_chlorophenylsulphonyl-aniline 2-nitro-4-para_methylphenylsulphonyl-aniline 4-chlor-3-amino-benzophenone 4-amino_3-nitro-benzophenone 4-amino-4'-chloro-benzophenone 4-amino-3-nitro-4'-chloro-benzophenone 2_amino-4,4'-dichlorobenzophenone 4-amino-2',4'-dichlorobenzophenone

3-amino-4-methyl-4'-methoxybenzophenone . , - - . ~ . . - . . . :
,.

4-chlorobenzoic acid 4'-amino-3'-methylphenyl ester 4-chlorobenzoic acid 4'-aminophenyl ester, The coupling components are preferably those of the formula O-C~ ~XCOCH2COCH3 wherein R4 and Yl are as previously defined.

The coupling c~mponents are obtained in simple manner by treating the corresponding amines with diketene, Examples of amines are:

5-amino-benzimidazolone 5-amino-1-methyl-benzimidazolone 5-amino-1-n-butyl-benzimidazolone 5-amino-1-phenyl-benzimidazolone 5-amino-1-p-chlorophenyl-benzimidazolone 5-amino-1-p-methylphenyl-benzimidazolone 5-amino-1-p-methoxyphenyl-benzimidazolone 5-amino-6-chloro-benzimidazolone 5-amino-6-bromo-benzimidazolone 5-amino-6-methyl-benzimidazolone 5-amino-6-methoxy-benzimidazolone

6-am~no-2,4-dihydroxyquinazoline 6-amino-4-methyl-quinolone-2 .. ... . . . . . . . . .
' ~ . ' ' ~ ' ~ ' .

: - ~

10~49~0

7-amino-4-methyl-quinolone-2 7~ i.no-4~6-dimethyl-quinolone-2 6-mono-7-chloro-4~methyl-quinolone-2 7-amino-4-rnethyl-6-methoxy-quinolone-2.

These heterocyclic amines are kno~ compounds. The diazotisation is effected by known methods.

The coupling preferably ta~es place in a weakly acid medium, advantageously in the presence o~ conven~ional agents that promote the coupling. As such coupling promoters there may be mentioned in particular dispersants, for ex2mple aralkyl-sulphonates, such as dodecylbenzenesulphonate, or 1,1'-dinaphthylmethane-2,2'-disulphonic acid or polycondensation products of alkylene oxides. The dispersion of the coupling component can also advantageously contain protective colloids, for example methylcellulose or minor amounts of inert organic solvents which are sparingly soluble or insoluble in water, for example optionally halogenated or nitrated aromatic hydrocarbons, for example, benzene, ; toluene, xylene, chlorobenzene, dichlorobenzene or nitro-benzene, and also aliphatic halogenated hydrocarbons, for example, carbon tetrachloride or trichloroethylene, and furthermore water-miscible organic solvents, for example acetone, methyl ethyl ketone, methanol, ethanol or iso-propanol, or preferably dimethyl formamide.

;. ,, ; . . .

,. : .. ~ . .... , -.. .

10~4910 The coupling can also advantageously be carried ou~ by conti.ntlously combi.ning an acid solucion o~ the diazonium salt wi~h an alkaline solution o~ t.he coupling component in a mixing nozzle, whereupon an ~mmediate coupling of the component occurs. Care must be taken tha~ the diazo component and the coupling component are present in equimolecular amounts in the mixing nozzle, and a slight excess of coupling c~mponent proves to be advantageous. This is most simply achieved by controlling the pH of the liquid in the mi~ing nozzle Furthermore, intense turbulent mixing of the two solutions in the mixing nozzle must be ensured. The resultant colourant dispersion is continuously drawn off from the mixing nozzle and the colourant separated by filtration.

Finally, the coupling can also be carried out by ~uspending the amine with the coupling component in the molar ratio 1:1 ln an organic solvent and treating the coupling mixture with a diazotising agent, in particular an ester of nitrous acid, such as methyl, ethyl, butyl, amyl or octyl nitrite The pigments of the present invention have a good texture and can be generally used without being conditioned If desired, however, the cr.ude products can be converted into a finely dispersed from by grinding or kneading, advantageously using grinding assistants, such as inorgani^ and/or organic salts in the presence or absence of organic solvents After the .

~084910 grindi.ng ~rocedurf~ the assistsnts are removed in the conventi.onal manner: soluble inorganic salts for example with water, and water-insoluble assistants for example by steam distillation. The properties of the crude pigments can often be ~mproved by treating them with or~anic solvents, pre~erably those having a boiling point above 100C
Particularly suitable organic solvents are: benzenes which are subst ituted by halogen atoms, alkyl or nitro groups, for example xylenes, chlorobenzene, o-dichlorobenzene or nitro-benzene, as well as pyridine bases, such as pyridine, picoline or quinoline, and also ketones, for example, cyclohexanone;
ethers, for example ethylene glycol monomethyl ether; amides, such as dimethyl formamide or N-methylpyrrolidone, as well as d~methyl sulphoxide, sulpholane or water alone, with or without pressure The aftertreatment can also be carried out in water in the presence o~ organic solvents and/or with the addition of surface-active substances.

;.
The aftertreatment is effected preferably by heating the pigment in water or the solvent to 100 to 200C, whereupon in certain cases an increase in the granular size and, in appropriate circumstances, a change in the crystal modifica-tion, occurs. The fastness to light and migration of the resultant pigments are thereby favourably influenced The pigments obtained according to the invention are suitable , i - ....
.. - . . . . . . ..

," ' ' ' ' ' . ', .
- , ~ .

10~4910 for coiourin~ org~nic material of high molecular weight of natural or sy~thetlc origin Such material can comprise for e~nple natural resins, drying oils or rubb~r However, it can also comprise modified natural materials, for example chlorinated rubber, oil-modified alkyd resins or viscose or cellulose derivatives, such as acetyl cellulose and nitro-cellulose, and in particular man-made organic polyplastics, that is to say, plastics which are obtained by polymeri-sation, polycondensàtion and polyaddition The following products may be mentioned in particular as belonging to this class of plastics: polyethylene, polypropylene, polyiso-butylene, polystyrene, polyvi.nyl chloride, polyvinyl acetate, polyacrylonitrile, polyacrylates, polymethacrylates; poly-esters, in particular esters of high molecular weight of aromatic polycarboxylic acids and polyfunctional alcohols;
polyamides, the condensation products of formaldehyde and ~` phenols (phenolic plastics)~ and the condensation products of formaldehyde and urea, thiourea and melamine (aminoplasts);
the polyesters used as varnish gums, namely both saturated polyesters, for example alkyd resins, and unsaturated poly-esters, for example maleic resins, and also the poly~ddition and polycondensation products of epichlorohydrin and polyols or polyphenols kno~m as epoxide resins; in addition thermo plastics, i.e. the non-curable polyplastics It must be emphasised that not only the homogeneous c~mpounds can be - -: - 12 _ ~ .. ...

.
:

1~84910 pig~ented according to the invention, but also mixtures of polyplasti.cs, as well as co-conden~ates and copol~mers~ for example those based on butadiene The pigrnen~s of the present invention are particularly suitable for colouring polyplastics, and the film formers or binders known as vehicles, especially boiled linseed oil, nitrocellulose, alkyd resins, melamine resins and urea-formaldehyde resins The pigmenting of the organic substances of high molecular weight with the pigments o~ the formula (I) is effected for example by mixing such a pigment, optionally in the form of masterbatches, with these substrates using roll mi.lls, mixing or grinding devices The pigmented material is thereafter brought into the desired final form by known processes, such as calèndering, pressing, extruding, coating, casting, or by injection moulding. It is often desirable to add plasticisers to the compounds of high -molecular weight before forming them in order to obtain non-rigid moulded articles or to diminish their brittleness Examples of such plasticisers are esters of phosphoric acid, phthalic acid or sebacic acid The plasticisers can be added in the process of the invention before or after the incorporation of the pigment dye in the polyplastics. In order to obtain different shades it is also possible to add, in addition to the compounds of the fonmula (I), fillers or other colouring constituents, such as white, coloured or _ 13 -: ' ' ' ,' ~. . - . ' ' ,' ' - .

black piglnents, in any amounLs to the organic substances.

For pigmen~ing lacquers and printing inks, the organic materials of high molecular weight and the compounds o~ the formula (I), optionally together with additives, such as fillers, other pigments, siccatives or plasticisers, are finely dispersed or dissolved in a joint organic solvent or solvent mixture. The procedure can CollSiSt for example in dispersing or dissolving each of the components individually or also several jointly, and only thereafter combining all the components The pigmen~ed organic materials of high molecular weight generally contain amounts from 0.001 to 30% by weight of a compound of the for~ula (I), based on the organic substance of high molecular weight to be pigmented Polyplastics and lacquers contain preferably 0.1 to 5% by weight, and printing inks contain preferably 10 to 30% by weight. The ~mount of pigment to be chosen depends primarily on the desired colour strength, on the layer thickness of the moulded article, and finally also on the content of white pigment, if any, in the polyplastic.

The colourants of the present invention are distinguished to s~me extent by their easy accessibility, and by their good fastness to heat, light, overstripe bleeding, migration and good resistance to atmospheric influences. Compared with _ 14 -., .~ .. . .
.

10~49~0 disazo pi~lents, they have the advantage that the after-treatment in organic solvents is not absolutely necessary in order to obtain a good textllre and fastness to migration, In the following Examples which illustrate the invention the parts and percentages are by weight unless otherwise stated.

- 15 _ .

. .

1~8~910 E~mple 1 18,5 parts of 2-ethylsulphonyl-5-triflLloromethyl aniline are stirred in 200 parts by vol~e of glacial acetic acid at room temperature and ater about 5 minutes,25 parts by volume of concentrated hydrochloric acid are added to the completely clear solution. The solution is cooled to 0C with ice and then 20 parts by volume of 4N sodium nitrite solution are added at 0 to 5C over the course of 15 minutes, After about 1 hour, excess nitrite is completely destroyed with sulphamic acid and the diazo solution is filtered cLear, 14.4 parts of 5-acetoacetylaminobenzimidazolone are dissolved in 20 parts by volume of 30% sodium hydroY~ide solution and 350 parts by volume of water at roam temperature, 2 parts of hyflo are added and the mixture is filtered clear, The solution of the coupling component is added to the diazo ~olution at about 5C in the course of about 30 minutes, The pll value is kept between 4 and 5 by addition of 30% sodium hydroxide solutbn, The batch is stirred for 6 to 8 hours at 20-25C, then heated to 80C, The pigment i8 collected by filtration and washed with hot water, The ~ilter cake i8 dried in vacuo at 70-80C, affording 28,9 parts (g6,8% of theory) of a ~ellowish brown powder of the formula _ 16 -` , .

, -1~849~0 ~113 O C ~N~I~COC~_N=N~2c2H5 H

The above product is recrystallised by an aftertreatment in o_diclllorobenzene (2 hours at 145C), yielding a pigment which colours PVC in bright reddish yellow shade of very good fastness to migration, light and atmospheric influences.

The following table lists further pigments which are obtained by coupling the diazo compound of the amine of column I with the acetoacetyl compound of the amine of column II and subsequent aftertreatment in the solvent of column IV, Column III indicates the shade in which PVC is coloured wlth 0,2'h of thls pigment.

.

_ 17 -.. . .
-.

-` 10t~49~

TAB~E
_ ~ .
I ~ I , Ll ~ I C) O O
~ o ~-1 ~ ~ ~ o o ~ ~a ~ ,S~ ,~ F
~1 t~ ~ J O IJ
O~r~ N CJ ~ C) Frl N rl N Q) F
V~ ~ ~ a ~
I ~ I ~ r~ o I O~ o ~ o o~ ~ ~ ~ o~ o~ ~ ~
. _ ...... _ ~ ~ ,'2 ~ 3 a) ~ ~
a) o ~o ~o ,~ t,.o r~ O ~ C rl O r~ O b~ W C O
C'U ~ ,'2 t~) ~ o a) r-l O r~ O ~-1 u~ h O O ~ o ~ h O ~ ho h ~o ~ O O ~ h ~ . ,,~ X
O N ~ O S_~
~.) ~

O ~ ^ I I I C `
~u ~ aJ ~ ~IJ al C~l-rl ~ rO o g d o rO0 d ~o uo ~C a O .~ ~0 ~
¢ u~
_ .
~' l O ~ I a) ~
~ a, ~ c a --~ O ~ h ~ O ~ aJ C
~ a) o P- o ~1 ~ - o N
~ o ~ o ~ N C O
U U C I _I P~ N .~ ~-1 N I td ~1) N
a I I ~ I c ~ u ~ a aJ u~ rl C ~ ~ I I ~ h h o o C I I ~CJ aJ 0 ~ ~ L~l rO ~ ~Ç N ,O
O ~ I O ~ I O U V 0 o h ~3 C ~ C u ~1 C O OP. O ~ o o O Orl ~ rl >~ a) ~ ~ C ~ ~
.~ -!~ NO ,~ ,C .~ ~1 0 ~ ~ ~4, aN J- t 4 C) rl O ,C ,C ~.) I N I ~1 t~
o ~ I I C C ~ a ~ ~ I
N ~ ' ~ I O ~
rl ~ I N O - ~ I I O I l I
~1 ~ 0P~ aJO ~ U O O ,r~ l o O N O ~1) 0 O
N~ t O l .(~'1 ~ ~ C ~ C td a a ~ ~
a ~ O ~ O
e o ra C a)~ 3 N ~ e e o e N ~3 e-,~U-rl e-r~ ~ w s~ w a w , e , ~ , , ~ , aJ , , ~: , ~ , ~ ~J ~ ~ ~ ~1 ~ ~ ~ ~ ~ D
O ,1 C-~ ~ I~ oo ~ O ~
: Z ~ ~1 _I ~1 -.
. .. . .

.~ .

~849~0 TAI31,E
__ . .~
C~
~~a o ~ra rC ~ _ _ U
OllJ E~ ~1 N 1:1) U~ '~
~c~ 4, o ~ ~a _ a) o 3 ~
ra ~ ~ ~ ~rl O O ~ O - O
~ ~ ~ '~
,~ a~ ~ a u~ P~
_ ~a ~ g o ~ I ,~ I ~
o ~ C~l o I ~ C~l o ~ o a~ ~ _I I X ~1 0~--I O ~
~s 5~ a :~ ~ o aJ ~ ~ h aJ P~ ra o o o ~ o ~ o o .
~ ~ ~ o ~ o ~ o ~ o ~ o ~~ o ,1 , o ~ I ~ ~ ~ ~ ~ O - ~ ~ ~
~ 4~t) r~ NE~ O ~ OE~ C.l O E3 0 ~ E3 0 N
.LI O I rl~::I N I NI N I N I NI rl I N
t~I rJ~ I oI a I oI ~aI ~o I ~I o ,o O I O 0~1O-r~ 0~1O-rlO~rl O IC)-rl O
3 N ~ N~ N ~ N ~ N
Cl~I O I I OI a)I ~u I o I oI o I O I
~ E3 u~ ~ ,Q U~ ~ LO,Q U~ r) rQ Lr~
_ ~U O I O I ~
g ~ O o ~~ hI
~ O ~ O
au o h ~d ~ Oh .C s~
. . ~ o o ~ o I
O ~
~J N ,~ V S~ ~1 ~ h 1:~ ~ I V ~rl ~1 ,~
~ rQ - U~ q O O ~ _I~ o I ~ I h~ ~ ~ 4 P~ ~ I h _I h ~1 ~ h h I U~
E3 O o ~ ~I h 1~ Cl ~ ~ - G~
o ~~ h t~ O a ~ v aJ ~

O ~ JJ ,~ O ~ O ~ ~ ~ O a~
~ P N o ,~ O E~ ~ h O I ~ rl Q~rl~ D I "O S
N _ I o u~
t~ ~ ~ t~ I O I ~I
rlI I ~J ~1 0 ~ u~
3 Q O O ~ d r~ ~ ~ h ~ O ~ ~_I N ~I h~ I ~
r~ rl O U-rl ~ ~ rl V~r~ ~ O
N ~ U ~` ~ S-l ~U
O ~ P JJ a) ~ ~--U
I I a~ u ~ ~,Q ~ a ~
_ O ~ U~ ~ I~ 00 ~ O ~ C~ ~) æ ~ J

_ 19 -!

- , , . . , . , ' ., . .'. ' ' ,: . , : ' , ' '' . - ' '' ' ' ' "~ ' ~, -' ~ . ' " "' . . . .
' ~' ', ' . ' ' ' ' ' ' . ' . ~

1~849~0 Exam~le 25 15 g o collodion cotton containing 35% of butanol, 15 g of a phthalate resin modified with castor oil, 15 g of a 70%
butanolic solution of a urea varnish g~m, 20 g of butyl acetate, 10 g of glycol monoethyl ether, 20 g of toluene and 5 g of alcohol are processed to a lacquer. This lacquer is then pigmented with 2 g of the colourant of Example 1 and 2 g of titanium dioxide (rutile) and ground, The lacquer is sprayed onto cardboard and dried, giving a yellow coating of very good fastness to light and overstripe bleeding and very good resistance to atmospheric influences, Example 26 To 100 g of a stoving lacquer consisting of 58,5 g of a 60%
801ution of a coconut alkyd resin in xylene, 23 g of a 65%
solution of a melamine varnish gum in butanol, 17 g of xylene and 1.5 g of butanol, are added 1 g of the colourant of Example 1 and 5 g of titanium dioxide, The mixture i9 ground for 48 hours in a ball mill and the pigmented lacquer i8 sprayed onto a clean metal surface. After stoving at 120C, a yellow colouration of good fastness to light and overstripe bleeding and good resistance to atmospheric influencesis obtained, _ 20 -~0849 ~27 0.6 g of the pigment obt~ined in Example 1 is mixed with 67 g cf polyvinyl chloride, 33 g of dioctyl phthalate, 2 g of dibutyl tin di.laurate and 2 g of titanium dioxide and the mixture is processed to a thin sheet for 15 minutes at 160C
on a roll mill. The yellow colouration obtained is strong and fast to migration and light.

Example 28 1 g of the pigment obtainPd in Example 1 is finely ground in an Engelsmann grinding machine with 4 g of a litho varnish of the composition:
29.4% of linseed oil-stand oil (300 poise) 67.2% of linseed oil_stand oil (20 poise) 2.1% of cobalt octoate (8% Co) and 1.3% of lead octoate ~24% Pb) Using a stereotype block, this varnish is printed in an amount of 1 g/m2 on art paper by letterpress printing A
strong, bright, yellow shade of good transparence and good gloss is obtained. In three- or four-colour printing, ver~r brilliant reddish yellow shades can be obtained by superimposing on blue.
The pigment is also suitable for other printing methods, such as intag~io printing, offset printing, flexographic printing, with equally good results. `
_ 21 -.

Claims (13)

What is claimed is:

1. Azo pigments of the formula wherein R represents an alkylsulphonyl group of 1 to 4 carbon atoms, an aralkylsulphonyl group or an arylsulphonyl group which is unsubstituted or substituted by halogen atoms, alkyl or alkoxy groups of 1 to 4 carbon atoms, an alkanoyl group of 2 to 6 carbon atoms or a benzoyl group which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups of 1 to 4 carbon atoms, an alkanoyloxy group of 2 to 6 carbon atoms, an aroyloxy group which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups of 1 to 4 carbon atoms, or represents the group -N=N-aryl, the aryl moiety of which can be substituted by halogen atoms, alkyl or alkoxy groups of 1 to 4 carbon atoms, alkanoylamino or alkoxycarbonyl groups of 2 to 6 carbon atoms, nitro, trifluoromethyl or carbamoyl groups, R2 represents a hydrogen atom, an alkyl group of 1 to 4 carbon atoms or a phenyl radical which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups of 1 to 4 carbon atoms, X1 and X2, each independently of the other, represents a hydrogen or halogen atom, an alkyl or alkoxy group of 1 to 4 carbon atoms, a trifluoromethyl or nitro group, Y represents a hydrogen or halogen atom, an alkyl or alkoxy group of 1 to 4 carbon atoms or a phenoxy group, n is 1 or 2, Z represents the NH-group or a group of the formula -CONH- or wherein R3 represents an alkyl group of 1 to 4 carbon atoms or a phenyl radical which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups of 1 to 4 carbon atoms.

2. Azo pigments according to claim 1 of the formula wherein R, X1 and X2 are as defined in claim 1, Y1 represents a hydrogen or chlorine atom, a methyl, methoxy or ethoxy group, and R4 represents a hydrogen atom or an alkyl group of 1 to 4 carbon atoms.

3. Azo pigments according to claim 2 of the formula wherein R4 and Y1 are as defined in claim 2, R5 represents an alkyl group of 1 to 2 carbon atoms, a benzyl group or a phenyl group which is unsubstituted or substituted by halogen atoms or alkyl or alkoxy groups of 1 to 4 carbon atoms

4. Azo pigments according to claim 1 of the formula wherein Y is as defined in claim 1 and R6 represents a methyl or ethyl group.

5. Azo pigments according to claim 1 of the formula wherein X2 and X4 represent chlorine atoms or methyl or methoxy groups, and X4 represents a hydrogen or chlorine atom or a methyl group,

6. Azo pigments according to claim 1 of the formula wherein X6 represents a hydrogen or chlorine atom, a methyl or methoxy group.

7. The compound according to claim 1 of the formula

8. The compound according to claim 1 of the formula

9. The compound according to claim 1 of the formula

10. The compound according to claim 1 of the formula

11. The compound according to claim 1 of the formula

12. A process for colouring organic material of high molecular weight which comprises the use of a pigment according to claim 1.

13. Organic material of high molecular weight which contains a pigment according to claim 1.