CA2006414A1 - Stilbene dyestuffs and light-polarizing films or sheets containing stilbene dyestuffs - Google Patents

Abstract

Stilbene dyestuffs and light-polarizing films or sheets containing stilbene dyestuffs Abstract Dyestuffs which in the form of the free acid conform to the formula I

in which X and Y have the meanings given in the descrip-tion and light-polarizing films or sheets containing an organic polymer, preferably a vinyl alcohol homopolymer or copolymer, and dyestuffs I.

Le A 26 260-Foreign countries

Description

The i~vention relates to stilbene dyestuffs and light-polarizing films or sheets, containing stilbene dye-stuffs.

Films based on polyvinyl alcohol (PVA) containing iodine or dichroic dyestuffs as polarizing agents are known.

Un~il now, it has been v ry predomi~antly the iodine-containing polarizers which have found industrial appli-cations, for example in passive li~iid cry tal displays for the visualization of information. In the ab~ence of moisture, these polarizer are charactsrized by excellent light fa~tness and outstanding dichroic properties in the long-wave region of the vi~ible spectrum. The active - agent of these films is the iodine/PVA complex (M.M.
Zwick. J. Appl. Polym. Sci. 9, 2393-2424 (1965)~, which admittedly absorbs a wide band of the daylight spectr~m, but not all of it. In the short-wave region, a "hole", i.e. a region of diminished extinction, is present, which is the rea~on tha the sh~ets have a characteristic blue colour ~hi3 has disadvanta~eous con~equences, if it is desired to produce white light. The light tran~mitted in unpolar-ized form dimini~hes the dichroism and thus the polariæa-tion psrfv~mance in this region. To increase it again, it is nec~ssary to incr~ase the concentration of iodine Z5 complex. HoweYer, ~his correction in ~he short-wave region re~ult~ in sxaessive extinction in the long-wave region. Thi3 leads to a si~nificant decrease of the transmi ted light in the transmi~sion ~etting in combina-tion with a decrease in the brigh~nes~ of ~he display w~ich is equippsd with this sheet. To achieve acceptable degxeeæ of brigh~ne~, compromiseR must be made.

Le A 26 ?60 - 1 -~0~

An important critical parameter of a display is its readability under various illumination conditions; it i5 usually stated as "perceived contras~ ratio (PCR =
Tl/T¦¦~; this ratio should be as large as possible. From this follows that the transmission on the one hand has to made as small as possible in the blocked setting (T¦¦) (readability in the dark) and, on the other hand as large as possible in the transmission setting (Tl) (readability in the light). This reguires a very uniform polarizing performance of the filter over the entire spectral range, which can usually not be achieved by maans of the iodine sheet.

There has not been a lack of attempts to replace iodine by dyestuff triples of dichroic dyestuffs ~o produce a neutral grey colour having a uniform dichroism.

However, this requires a range of high-performance dyestuffs. In addition ~o good light and weather fast-ness, they must have a high extinction and a high dichxoism in ~he matrixt in addition, they must not have secondary densities which have lower dichroism. Thus, preferably polyazo dyestuffs have been proposed (~A 59/145,255, JA 60/156,759, JA 60/168,7433. However, althouqh dichroism i~ a wide-spread property with dye-stuffs (cf. W. ~anle, H. Scherex, %eitschr. Naturforsch.
6a, 437-439 (1951)), it haæ sofax not been possible to achieve or surpass the ~pectral properties sf the iodine ~heet. This can be attributed, on the one hand, to the lack of good blue shades, and, on the other hand, to he requirement of high dichroism o~ the system dyestuff/
matrix.

Surpri~ingly, it ha~ now been found that certain novel stilbene dye3tuff~ have excellent dichroic proper~ies and ars highly suitable for the production of Le A_26 260 - 2 -ligh~-polarizing films or sheets.

(In what follows, a definition of a radical or index once given is maintained in the further text).

The invention accordingly relates, in one aspect, to S dyestuffs which, in the form of their free acid, conform to the formula x ~ H-CH ~ ~ Y

in which X, Y signify -N=N-R, -C~3, -CONH2, -CONHRl, -CONRlR2, -COOH, -COOR1, -CN, -NO2, -NHz, -NHRl, -NRlR2, -OH, -ORl, -R1CONH-, -O-CO-R1 halogen or a substituted or unsubstituted hetero-cyclic radical, with the proviso that at least one of the radicals X~ Y represents -N=N-R, in which R represents an aryl or a heterocyclic radical and Rl, R2 represent alkyl, cycloalkyl, aryl or aralkyl, which may be interrupted by O and/or S, and in which furthermore the radicals mentioned for R, R1 and R2 can be substituted, the dyestuff which, in the form of its free acid, conforms to the formula I where = Ho35~3N-N~N=N-H03s Le A 26 260 - 3 ~

and Y = H035~N=N~-N-being excepted and the azo dyestuffs containing a maximumof eight azobridges.

In particular, R signifies an aromatic radical from the benzene or naphthalene series, ~rcS2rably of the formula~

RS ~ ~6 in which R3 si~nifies H, OH, -ORl, -NH2, -NHRl, -N~lR2, -NH-CO~1, -O-CORl~ -N=N=Rll, a heterocyclic radi-- cal~ :
R4, Rs, R7, R8, R9, Rl signify H, halogen, -OH, -ORl, -NH2, -NHRl, -NRlR2, Rl, -SO3H, -SO2-NH2, -SO2-NHRl, -SO2-NRlR2, -O-CO-Rl, -NH-CO-Rl, R6 signifies H, -N=N=Rll, a substituted or unsub-stituted heterocyclic radical and Rll signifies a substituted or unsubstituted aryl radical, preferably a substituted or unsubstitut-ed phenyl or naphthyl radical or a substituted or unsubstituted heterocyclic radical or a nitrogen-containing heterocyclic radical.
,:
Preferred radicals R and R11 of the benzene series are as follows:
., Le A 26 260 - 4 -, , . .

4~

~ R3 , ~

In particular, suitable radicals are those which are derived from phenol and its substitution products, if appropriate subsequently alkylated or acylated, and from aniline and its substitution product also, if appropri-ate, subseqllently alkylated or acylated. Examples are:
H, ~ CH~, ~ C2H5, -CH2-CH2-OH, ~ H , ~ H , : ~ NH2~ ~ ~CH3 ~ ~CH3 \CH2-CHz-OCH3 ~N~CH3 ~N~ ' ~3N _ N _ R l 1 ~N = N _ R l 1 .
CH~ OCH3 CH3 =N_Rl 1 ~N-N-Rl 1 , ~N=N-Rl 1, -CH~ CH3 OCH3 ~N=N Rl 1 , ~N=N_Rl 1, ~
OCH3 HN~ 503H

.

Le A 26 260 - 5 -,. . . .......................

Preferred radicals R and R11 of the naphthalene series are listed below:

Y~
Rl2 = -OH, -NH2 ~ 1 0 ~8 ~ 9 R13 is H, if R14 = -N=N-R11 or H, and is -N=N-R11, if R14 = -OH, -NH2, R14 is -OH, -NH2, -N=N-R11, 1S ~ ~14 ~R6 ~<
~ R6 ~ 16 R15 ~ R16 Rl5, Rl6 are H, -OH, -OR1, -3-CORl, -NH2, -NH-Rl, -NHRlR2, -NH-CO-R1, -SO3H, R17 is H, -SO3H.

In particu}ar, the ~ollowing radicals R and R11 of the naphthalene seriss are preferred:

B

~lB i5 H, OH, N~2, -NH-CO-R~, -NH-R1, -N=N-R~l, -S03H, h~ ZE~ - 6 -~=19,~, 50 .H

503H SO ~H H035 ~ 21 Rl9 R
Rl9 is H, -N=N-Rll, R20, R21 are OH, NH2, -O~CO-Rl, -NH-CO-R1, OH OH ~20 CH Rl 7 , ~,~ = Rl ' `~

S03H 53~ 503H
Preferably, R ~nd R1l are derived from the (substituted) S I acid:
: OH
R22 is -NH-Rl, -NH CO-R1, -N=N-R

~03S R22 : PrefPrred radicals X, Y, R3 and R5 of the heterocyclic ~: series have the formula ~: Rl9 -X Z
: in which ~ is a C or an N atom, where the free valence of carbon has been saturated by a double bound, and Z represents the remaining members of a preferably ~: 5- or 6-membered monocyclic or bicyclic or tricyclic ring 15 which can contain 1 to 3 hetersatoms from the series con-sisting of ~, O, S and i5 subatituted or unsubs~ituted.

Le A 26 260 - 7 -~ ~ ' ~o~

In particular, they are derived from the following heterocyclic systems:
triazole, pyrazole, ben~otriazole, naphthotriazole, oxazole, imidazole, thiazole, oxadiazole.

Preferred radicals R and R11 of the heterocyclic series have the formula R19 -C Z
in whicn Z represents the remaining members of a preferably 5- or 6-membered monocyclic or bicyclic or tricyclic ring, which can contain 1 to 3 heteroatoms from the series con-sisting of N, O, S and is substituted or unsubstituted, the free valence of carbon being saturated by a double bond.

In particular, R and R11 are derived from the following heterocyclic systems (coupling components):
thiophene, triazole, pyrazole, pyridine, benzotriazols, pyridone, naphthotriazole.

In addition, Rll is derived from the following hetero-cyclic systems (diazo components)-thiadiazole, thiazole, benzothiazole.

Suitable het~rocyclic radicals R and R~l are in particular a ~ubstituted 5-amino- or 5-hydroxypyrazole radical.

Further preferred radicals R ~nd Rll are those of the formula:
-~-A-N=N-)p-L

k~ h_~Q - B -in which A is a substituted or unsubstituted phenylene or naphthalene radical, L is a substituted or unsubstituted phenyl or naphthyl radical and p is 1, 2, 3.

In particular, A represents and L represents Examples of radicals R and Rll are:

HO ~ , CH30 ~ , ~ J H3C ~ CH~ !-~ONH~- ~O~'i, ~503H, `-_'H3-CO-NH OH OH

~503H, CH3-CO-NH ~ 503H , ~e A 26 260 - 9 - ?
, :.

O-,~H OH Cl ~ ~ O-,~jlY. OH

~ ~ 503H, ~ 503H~

OH OH
;G -.~03f OH H03S OH

~2'~ ~ ~ ' . ., ~J
¦ ~ ~ O-.~H
503H ~ _ ~ S03H

H03s- ~503H, Ho3s~3~\503U, . OH OH
3 h'~ " ~ 503H O-NH ~ 503H

r H 3 - C O - !`1 H ~ ,~,~

~ 1 9H

'~35~-'~ ~ O-NH ~ 503H

~4 o~

.o~
~ 21 L~ A 26_26~ - 10 -R20, R21 are H, C1-C4-alkyl (methyl), C1-C4-alkylcarbonyl, in which alkyl can be substi uted by -OH, OAlk, CN or are (2-hydroxyethyl, 2-cyanoethyl), phenyl, benzyl, benzoyl which can be substituted by -NO2, S-OH, Cl-C4-alkyl (methyl), halogen, -SO3H, -COOH, _ ~ r. ~ I
R~N-~. I ~ ~R21 ~7 o~y N=~ `~'~
,yo35J~N~
~ S O 3H ) n n is 0, 1 or 2 ~$ N= ~ ~ N

50~H)n .Y N H 2 \~=-N-RI I
HO~S

.~03S X ~ ~ ;N-R11 ~ ~ ~S03H

S~3H ~ 03H

.~03S N_N~ 03s i N

e A 26 260 ~

41~

'H _C~H OH
!~ ~X~, 03H N=,~ Rl 1 HO3S N-N_Rl 1 OH

~,C.Y ~ 10CH3 ~N = ,~ ' 1 ~0~ N = N - R ! 1 OCH

CH
~ 3 CH3~N=N-R1 1 ' ~N=N-Rl 1 CH ~

=N_RI ~ `$N=N_Rl I

:~

Le A 26 260 - 12 -. , ' ' ' '' " ' .

2 ~
J~l R 2 4 R ~ 2 R23 is H, Cl-C4-alkyl (methyl), -COOH, R24 is a substituted or unsubstituted aryl radical, preferably ~ So~H, - ~ j ~ S3 -~ ~ N=N-~ ~ 503H

The radical R pxeferably contains 0, 1, 2 or 3 azo groups.
Preferred are compounds of the formula I in which X=Y=-N=N-R.
Halogen (X, Y~ preferably repr~sen s F, Cl, Br, I.
He~erocyclic radicals (X, Y) are preferably derived from a 5- or 6-membered heterocycle which contains 1 to 3 heteroatoms from the series Consisting of N, 0, S, for example triazole, pyrazole, oxazoler imidazole, thiazole, oxdiazole, thiadiazole,;benzothiazole.
Alkyl (Rl, R2) preferably represents C1_CB_a1kY1 ~methyl, ethyl), cycloalkyl (Rl, R2) preferably represents C3-C7-cycloalkyl (cyclopentyLI cyclohexylj.
Aryl (Rl, R2~ praferably represents phenyl and naphthyl.
Aral~yl (Rl, R2) preferably repxesents phenyl-Cl-C4-alkyl ~benzyl, phenethyl).

Suitable substituents for the alkyl and cycloalkyl radicals (Rl, R2) are, for example, halogen ~Cl, Br, F), -0~, -CN, C1-C4-alkoxy and the like.

Suitable subs~ituants for the aryl and aral~yl radicals I.e A 26 2~0 - 13 ~

, ' :

(R1, R2) are, for example, haloyen (Cl, Br, F), -OH, C,-C4-alkoxy (methoxy), C,-C4-alkyl (methyl), CF3, NO2, CN.

Compounds I can be prepared in analogy to processes known from the literature. Compounds II to V, th~ preparation of which is illustrated below, can serve as starting material.
CH3-C0-NH ~ H-0 ~ H3C ~ ~ N02 C.~! 3 - C C - ~IH~H - C H~}No 2 HCl ~ (II) H2~ ~ H=CH ~ No2 NaHS
S03~ ~
~III) CH3-C0-~H ~ ~ H=CH ~ NH2 \ NaHS HCl 503H
( I V ) H2N ~ } CH=CH ~ 3 ~H2 SO~H
( v ) - ~urther possible syntheses of these and similar suitable intermediates for the synthesis of dyestuff can be found in DOS (German Patent Specification~ 3,805,513; see in p~rt~ular Example 2 and Example 2ter.

~he ~yn~hesis of the dye~tuff from these compounds is carried out in the usual manner by diazotization and coupling onto sui~able coupling components.

- Compound III i~ diazotized, and the product is Le A 26 260 - 14 -.

.
, coupled onto components such as phenols, aniline~, (aminohydroquinone dLmethyl ether~, benzoyl I acid, acetyl gamma-acid, N-(4-sulphophenyl~-5-pyrazolone etc. The phenolic OH groups of th~ products from the phenol couplings can then be sealed ~y alkylation.

The free amino groups of the product from the aniline couplings can again be diazotized, and the product again be coupled onto phenol~, anilines, benzoyl I acid, acetyl gamma-acid etc. Finally, the nitro group on the dyestuff can be reduced, and the free amino group can be coupled onto the coupling components mentioned, which makes it possible to prepare "unsymmetrical" compounds.

The free amino groups from the aniline coupling or the reduction of the nitro groups can also bs acylated, for ex~mple with benzoyl chloride.

- Compound (IV) is diazotized and coupled onto components as phenoles, anilines (aminohydroquinone dimethyl ether), benzoyl I acid, acetyl gamma-acid, acetyl H acid, N-(4'-~ulpho-diphenyl)-5~pyrazolone, etc. The phenolic OH group~ of the products from the phenol couplings can then be se~led by alkylation.
~he free amino group~ of the products from the aniline couplings can again be diazotized, and the product again be coupled onto phenols, anilines, be~zoyl I acid, acetyl gamm -acid etc. Finally, the acetylamino group on the dyestuff can be cleaved, and the free amino group ~an be coupled onto the coupling component~ mentioned; thus, it i8 possible al~o to prepare the derivative~ which, with respect to ths position of the ~ulpho group~, are isomers to those prepared frsm ~III). The free amino gxoups from the aniline coupling or the cleavage o the Le A 26 260 15 -^- 2~0~i4~4 acetylamino group can also be acylated, for example with benzoyl chloride.

- Compound (v) can be tetrazotized, and the product can ~e coupled onto the abovementioned coupling com-ponents. The phenolic OH groups of the products from the phenol couplings can then be sealed ~y alkyla-tion. The free amino groups of the products from the aniline couplings can again be diazotizedJ and the product ag~in coupled onto phenols, anilines, benzoyl I acid, acetyl gamma-acid etc., and they can also be acylated, for example with benzoyl chloride.

- The amino groups of the monoamino compounds III
and IV can be conYerted to the corresponding halo-gen, CN, OH compounds ~tc. according to Sandmeyer or, for example, to various d rivatives (triazole, pyrazole etc.). After reduction of the nitro group or hydrolysis of the acekylamino group, the mono-amino compound~ obtained can be coupled to giv~ azo dyestuffs.

20 ~ - Diamino compound V can be condensed with azodye-stuffs which contain a nitro group, preferably in a 4-po~ition with respect to an azo group, to form azoxy bridges, which can subsequently be reduced to azo bridges ~ treatment, for example, with glucose.
Likewi~e, 4,4'-dinitros~ilbene-2-~ulphonic acid ~Preparation see DOS ~erman Patent Specification) 3,805,513, ExampIe ~) can be Gonden~ed with azo dye~tufs which contains an amino group, preferably in the 4 po~ition with~respect to an azo group, to ~orm a~oxy bridges, which can likewi~e be reduced to azo bridges.

In ~ further aspec~, the invention relates to light-Le A 26 260 - 16 -4~

polarizing film~ (sheet~) which contain an organic polymer and one or more compounds of foxmula I.

The organic polymer is preferably an oriented polymer which forms transparent films and i6 compatible with S dyestuffs which contain~ acidic groups. Examples of such a polymer are: liquid-cry~talline polymers, for example based on polyesters, polyamides, cellulose aceta~e, vinyl alcohol homopolymers and copo].ymers and vinyl acetate homopol~mers and copolymer~, where the comonomer~ present can b~, for example, èthylene, propylene, cro~onic acid, (meth)acrylic acid, maleic acid. Polyvinyl alcohols which have been prepared by complete or partial hydrolysis of polyvinyl acetate, in particular those types which have a viscosity of > 4 mPa.sec2, preferably 20 to 70 mPa.sec2, at 20C in 4~ strength a~ueous solution and a hydrolysis degree of > 8Q mole %, preferably 85 to 100 mole %, are preferably used. The films preferably have a thickness of 10 to 150 ~. Preferably, those sheets are u~ed which ha~e stretched at room temperature or elevated temperature, preferably at 80 to 160C, by 200 to 1000 ~.

The films preferably have a thickness of 10 to 150 ~. The films preferably contain 0.01 to 10 % by weight, parti-cularly preferred 0.5 to 6 ~ by weight, relative to the weight of the film, of the dyestuf~ or the dyes~uff mixture. The films are coloured in the u~ual manner, fsr example by colouring the polymer which is dissolved (in water). It i~ recommended ~o fre0 the dye~tuff~ or dye-stuff salta be~ore use sf foreign salt~, or ex~mple by recry~tallization, ex~raction and/or dialysifi.

Ths dichrolsm of tha ~y~tem can be con~idar~bly enhanced by addition of polyhydric alcohols, ~uch as glycol, glycerol, diglycol, trimetholetha~e, trLmethylolpropane, pentaerythritol, ~orbitol~ their ethers, ~uch as glycol Le A 2_6 260 - 17 -monomethyl ether, glycol monoethyl ether, glycol dLmethyl ether, di~lycol diethyl ether, hydroxy amine~, such as propanolamine or amides, such as DMF, N-methylpyrroli-done, pyrrolidone, e -caprolactam, to the casting solu-tion. The additives can be used alone or, more advantage-ously, in mixtures, in which lower monohydric alcohols, for example methanol, ethanol, propanol, i-propanol, can also be pxesent as components of the mixture. The addi-tives are added to the casting solution in amounts of 1-50 % by weight, relative to the casting solution.

The film is produced in a manner known per se from the solution by casting.

If desired, the dyestuff-containing ilms can also be sub~ected to an aftertreatment, for example with aqueous boric acid solution, in order to improv~ ~he light permeability or the polarization coefficient. The condi-tions under which this aftertreatment iæ carried out can ~ary, depending on the film material and dyestuff.
Preferably, a 1 15 % strength by weight, particularly preferably a 5-10 % strength by weiqhtl boric acid ~olution i8 used at 30-80C, particularly preferably at 50-~C.

Preferablyr 6urfactants and, if desired, inorganic salts are added to the boric acid solution. The ~urfactants can be nonionicl cationic or anionic; preferably, they are nonionic. Example~ of nonionic ~urfactant~ are: addition products o~ e~h~lene oxide with higher alcohols or addi-tion products of ethylene oxide with nonylphenol. Prefer-ably, 0.005-0.5 % by weight, particularly preferably 0.02-0.2 % by w0ight, of surfactant i8 used, relative to the water.

Suitable inorganic ~alts are preferably sodium sulphate Le A 26 ?60 - 18 -and furthermore potassium sulphate, sodium chloride, potassium chloride, sodium nitra~e, potassium nitrate.
Relative to the water, preferably 0.1-5 % by weight, particularly preferably 0.3-3 % by weight, of inorganic salts are used. If desired, this can be followed by a fixation treatment with an aqueous solution of a high-molecular weight cationic compound.

The light-polarizing films or sheets can be compounded or laminated with other materials in a manner known per se.
Examples of suitable protective coatings are sheets made of a tetrafluoroethylene/hexafluoroethylene copolymer or another fluorohydrocarbon resin, a polyester, polyolefine or polyamide resin,a polycarbonate or cellulose ester, preferably cellulose triacetate, cellulose tripropionate, cellulose tributyrate.

Besides being used in light-polarizing films, the dye-stuffs of the formula (I) can be used alone or in mix-~ures for rendering ordered structures visible in the analysis of polymers and in biological material.

Example 1 a) Synthesis of the dyestuff:

R-N=N ~ H-CH ~ N=N-R

OH

3CONH~ 503H

29 g (0.1 M) of 4,4'-diaminostilbene-2-sulphonic acid (prepared according to DOS (Germa~ Patent Specification) 3,805,513, Example 3) are ~u~pended in 1 1 of water.
e A 26 260 - 19 -4~L~

83 ml of concentrated hydrochloric acid are added and 51 ml (0.22 M) of ~odium nitrite solution las an ~pproxi-mately 30 % strength ~olution) ar~ added dropwise slowly at room temperature. The suspension is stirred overnight.
After this time, it should be possible to detect a nitrite excess which is destroyed by the addition of sulphamic acid solution. This tetrazonium salt solution i~ ~lowly added dropwise at room temperature, while controlling the pH, to a solution of 69 g (0.2 M) of l~hydroxy 6-ben~oylaminonaphthalene-3-sulphonic acid in 0.5 1 of water, the pH being maintained between 6.5 and 7 by dropwise addition of 10 per cent strength ~odium hydroxide æolution. After ~tirring overnight, the preci-pitated dyestuff i~ filtered off wi~h suction and washed several times with small portions of water. The dyestuff i~ then di~solved in water and subjected to dialysis, to separate off salt~; the dye~tuff solution obt~ined is then evaporated, and the residue is dried. Yield: 95 g.
.
b~ Manufacture of the sheet 9.9 g of ~MOWIOL 28-99 (hydrolyzed polyvinyl acetate;
degree of hydrolysis 99.4 + 0.4 mole %; vi~cosiky of the 4 % strength of aqueous solution at 2DC:28 + 2.0 mPa.sec2; from Hoechst A~) and 0.1 g of the dy0 of Example la are di~olved in 190 ml of water by hea~ing ~he mixture at 9~C for 2 hours with ~tirring. 5 g of methan-ol and 2.5 g of glycerol are added to 92.5 g of the 1 ~
strength, relative to the polymer, dye~tuff solution o~tained. By mean~ of a knife, 50Q ~ thicX lay2rs are applled ~rom thi~ ~olutlon to a clean glassplate, and the l~yers thu~ obtained are dried in air at room ~emperature on a support i~ an exactly horizontal position. The resulting dry ~heets are peeled off from the gla~splate;
~hey have a violet colour and are about 40-50 ~ ~hicX.

Le A 26 260 - 20 -c) Stretching of the sheets To produce dichroic properties, the sheets are stretched.
To this end, th~y are heated in a drying cabinet at a constant temperature of 130C for 15 minute~ and then stretched at a speed of about 10 cm/min to about 700 % of their original length. The stretched sheets have a dichroic ratio of about 43 at the absorption maximum (570 nm~, measured with polarized light; losse~ due to reflec-tion are not taXen into account in the measurement.

d) Sheet manufacture on the casting machine O.2 g of the dyestuff of Example la is dissolved in 100 g of hot water. 10 g of glycerol are added, and 19.8 g of ~NOWIOL 28-99 are stirred into the cooled so'ution. After stirring at room temperature for 1 hour, the mixture is heated to 90C, and stirring is continued at this temperature until, after about 3 hour~, a homoge-nous solution has been formed. At 50C, 5 g of methanol are then stirred in. The warm solution i~ filtered through a filt~r pre~, while injecting air, and i8 then ~0 degas~ed by evacuation. The casting solution i~ pourable and stable at 30~C.

To produce a sheet, the casting solution is applied continuou~ly by means of 250 ~ knife to the casting wheel ~wheel diameter 25 cm, rotating speed about 7.5 min per revolution) which has been preheated to about 50~C. The la~er i~ dried by pa~ing heated air over it, and the solidified sheet i~ continuou31y peeled off ~he wheel and additionally dried. The sheet obtained i~ about 40 ~
~hick. It i~ ~retched as described above in c), leading to similar result~.

e) Rxactly analogou~ly as in Example la, analogous Le A 26 260 - 21 -dyestuffs are obtained by using the coupling components mentioned (the lina -- denotes in each case the coupling site), which are incorporated into sheets according to lb. Stretching according to lc gives dichroic sheets.

OH

rH~-CO-NH SO~H

,~J

OH

HO~S

OH

HO ~S S 03H

N~2 OH
.
HO~S~

Le A 26 260 -- 22 -Further dyestuffs are prepared analogously to Example la from the following coupling componentsO

OH OH
H035 ~ ~ ~ ~ NH ~

`H3C-CO-NH OH

.~O~

Cl ~ O-NH OH
0.'1 1 1 , OH H~C CO-NH OH

NH SO~H S03H 503H

OH ~ O-NH OH

CH3 ~NH S03H S03H S03H

Le A 26 260 - 23 -` ZÇ~ 4 OH
~ = CH33~

. ~
OH ~=~0 - NH O.Y
CH 3 - CO - N !t~ [~

5031t 50~H
OH OH
~O-NH~r ~ ~'1SO3H

503H <~CO-NH

HOOC~_N
$~N - N~3s03 H

OH
HOOC`~=N
~N ~ 35 0 3 H
OH
~0~

OH
C O - N~ 5~ --Cl HO ~G~S ~1 NH2 ~ o--NH
503H '==~ SO~H

The products obtained from the coupling onto phenols can be ~sealed~ by subsequent alkylation, for example methyl-ation using dimethyl sulphate.

Example 2 a~ 17.3 g (0,1 M) of 4-aminobenz~ne sulphonic acid are dissolved into 200 ml of water in combination wi~h about 7 ml of sodium hydroxide solution (45 %
strength) and 2~ ml of concentrated hydrochloric acid are then added all at once. The freshly precip-1~ itated ~uspension is diazo~ized at 5-10C with 7 g of sodium nitrite in 15 ml of water. After 15 minutes, the product is'filtered off with suction and washed on ~he filter with icewat r. The moist product is immediately stirred into 100 ml of water (caution: the dry product is explosive). To the suspension of diazonium salt thus obtained is added dropwis~, with vi~orous stirring, a cold solution of - 34.1 g (O.l M) of 8-amino-1-hydro~y-naphthalene-3,6-disulphonic acid monosodium salt and 5~5 g of sodium carbonate in 100 ml of water over a period of 45 minutes. The mixture is stirred for 12 hours while waxming to room temperature, the product is filtered off with suction and washed neutral. This gives a dyestuf~ paste of *he formula:

~e A 26 260 - 25 -. .

Ho35 ~ N- ~

H035 SO~H

b) The dyes~uff paste from a~ is dissolved together with 40 g of sodium carbonate in about 500 ml of water, if necessary with heating, and ~hen coolad to below 10C. The tetrazonium salt solution from 14.5 g ~0.05 M) of 4 ~ 4 ' -diaminostilbene-2-sulphonic acid prepared according to Example la is added dropwise to the suspension obtained over a period of 30 minute~, while maintaining the pH at 6.5 to 7 by metering in 10 per cent s~rength of sodium hydroxide solution. The mixture is stirred overnight, the dyestuff is filtered off with suction, washed neutral with water and then dissolved in water and dialyzed to separate off salts. The dyestuff 501u-tion is evaporated and the residue is dried. The : 15 dyPstuff obtained has the structure: -R-N=N ~ H=CH ~ N=N-R

-- R = ~ ~
H~S H03S 503H

c) The following coupling componPnts which can be prepared ~nalogously to 2a) can also be used:

A 26 ?6~ - 26 -HO3S ~ / - < ~ N=~

H03S ~ N=N ~ N=N ~, ~\ .
H03S ~C3H

~Hz OH
HO 3 S{~N = N\~-¦503H
lH2 H035 ~ / ~ ~ 503H

H035 ¦' OH

OH

H3S~N=~so3H
_ H03$
OH

~O~S ~ N- ~ 503H
~3S

la A 26 260 - 27 -; ' d) Exactly analogously, the dyestuff of the structure:

R-N=N~H=CH~3 N=N-R

~03S HO~S S03~

is obtained by coupling the tetrazonium salt solu-tion of ~xample l~ first ~t a-p~ of 4.5-5.5 onto 1-hydroxy-8-aminonaphthalene-3,6-disulphonic acid and then coupling the diazonium compound from 4-amino-ben~ene sulphonic acid prepared according to Example 2a twice onto the product at a pH of 7-7.5.

_The other components mentioned in c) can also be reacted in reverse order to give analogous dye-stuf~s.
Example 3 a~ At a maximum temperat~lre of 10C, a ~olution of 30.6 g ~O.2 M) of 2,5-dLmethoxyaniline in 500 ml of water (to which concentrated hydrochloric acid is added until a clear solution is fonmed) is added dropwise to-the tetrazonium salt solution prepared according to Ex~mple la, with stirring, while maintaining a p~ of 3 to 4.5 by simultaneous meter~
ing in of sodium hydroxide ~olution. After stirring ~ralgh~ and warming to room temperature, the coupling reaction i8 comple~ed. The product is filtered off with ~uction and carefully washed neutral with water. ~he d~estuff obtained after drying weighs 57.2 g and ha~ the formula:
~e P._6 26rJ - 28 -~64~

R-N=N~H=CH~3N-N-R

~ 3 R - H2N~

Instead of 2,5-dimethoxyanili~e, it is also possible to use 2-methoxy-5-methylaniline, 2,5-dime~hyl-aniline, 3-methylaniline, 3-acetylaminoanaline, 1-naphthylamine, 1-amino-2-ethoxy-naphthalene-6-S sulphonic acid or anilinomethane sulphonic acid etc.

b) The intermediate product obtained in a) is tetrazot-ized in aqueous hydrochloric acid with sodium nitrite while letting it stand overnight at room temperature r and the tetrazonium salt solution obtained, after destruction of the nitrite excess, is coupled onto 1-hydroxy-6-benzoylamino-naph-thalene-3-sulphonic acid at a pH of 6.5 to 8. The dyestuff obtained has the formula:

R-N=N{~CH=CH~N=N-R

OH OCH ~

R = O--C0~ J~ OCH3 d~ -- 29 --c~ The other compounds mentioned in Example le and 2c can also be used as components of the final coupling reaction, and phenolic coupling components can subsequently be "sealed" by alkylation.

The dyestuffs obtained are incorporated according to Example lb into a sheet, which is subsequently ~tretched.
Example 4 a) 8.8 g (0.01 M) of the dyestuff from Example le formed by coupling of the tetrazonium salt from la onto 1-hydroxy-6-acetylaminonaphthalene-3-sulphonic acid are stirred in 200 ml of 2N sodium hydroxide solution at 80C until the acetyl groups have been completely cleaved off (monitoring of the reac~ion by thin-layer chromatography). The reaction mixture is neutralized, cooled, and the residue is filtered off with suction and washed neutral.

b) The dyestuff formed according to a) is dissolvPd in 100 ml of sodium hydroxide solution, 1.8 g of sodium nitrite are added to the solution, and the solution is then run into excess hydrochloric acid. After standing overnight at room temperature, the tetrazo-nium salt solution has been formed; excess nitrite is destroyed by means of su~phamic acid, 2 y of phenol dissolved in sodium hydroxide solution are then added dropwis~, and the pH is brought to about 9 with sodium hydroxide solution. After stirring for 3 hours, the coupling reaction is completed. The product is filtered off with suction and washed neutral.
Instead of phenol, it is also possible to use the ~e A ~6 260 - 30 --other coupling componen~s listed in Tables le and 2c as Pnd groups.

c) The dyestuff formed according b) is dissolved in 100 ml of lN sodium hydroxide solution, and 4 g of dimethyl sulphate are added to the solution with stirring. Afer about 1 hour, the methylation is completed. The producted is filtered off with suction, washed neutral and dried. The dyestuff obtained has the formula:

R-~=N ~ ~-CH ~ N-N-R

OH

R CH3 ~ N=N 503H

Instead of dimethyl sulphate, it is also possible to convert the phenolic groups with diethyl sulphate or benzyl bromide to the ethers.
Exam21e 5 a) The tetrazonium ~alt solution from Example la is added dropwise at about 10C to the solution of 68.4 g tO.2 M) of l-hydroxy-8-acetylaminonaph-thalene-3,6-disulphonic acid (mono~odium salt) in ;~ 0.8 1 of water, during which the pH is maintained at 6~5-7.5 by dropwise addition of 2N ~odium hydroxide ~olution. The coupllng reaction i6 then allowed to go to completion overni~ht, whiIe heating to room temperature. The ~roduct is filtered off with suction, washed neutral with water and dried. Yield:
Le A 26 26Q - 31 -~no~

60.5 g of a ~lue-~iolet soluble dyestu~f.

b~ 20 g of the dyestuff from a) are heated in 200 ml of 2N sodium hydroxide solution at about 80~C, until the acetyl groups have been cleaved off. The mixture is then acidified with hydrochloric acid, the pro-duct is filtered off with suction, washed neutral and dried. This gives 14 g of a dyestuff which, in the form of the free acid, has the following for-mula:

= = N--~C H = C H~

H035 503H H03S SC3.

An analogous dyestuff is also obtained from 1-hydroxy-8-acetylaminonaphthalene-3,5 disulphonic acid, followed by clea~age.

The dyestuffs can be incorporated according to Example lb into a s~eet, which subsequently is stretched according to lc.

"UnsYmmetrical" dyestuffs A suitable intermediate for the preparation of "un-6ymmetrical" compounds is obtained analogously to the data ~n German Patent 1,065,838 (Geigy) by replacing benzaldehyde by 4~acet~1aminobenzaldehyde. Likewise, the product described in DOS (German Patent Specification) 3,80~,~13 Example 2ter can be converted into a suitable in~e~mediate by reduction of the nitrs group.

Lé A 26 260 - 32 -~6~

Example 6 a) 4-nitro-4'-acetylaminostilbene-2-sulphonic acid:

45.6 g (O.28 M) of 4-acetylaminobenzaldehyde and 59.8 g (0.25 M) of sodium 4-nitrotoluene-2-sulphonic acid are stirred into 90 ml of DMF, 9 ml of piperid-ine are added to the mixture, which is then heated at 140-150C for 3 hours. The volatile components (piperidine and water) are then distilled off, 9 ml of piperidine àre added to the residue, and the -mixture is again heated at 140-150C for 3 hours;
this process is repeated once more. The DMF is then distilled off in vacuo, and the residue is taken up in 200 ml of hot water. After cooling, the product is filtered off with suction, washed with a small amount of water and dried: yield: 65 g (68 ~).
b) 4-nitro-4'-aminostilbene~2-sulphonic acid:

I9.2 g (O.05 M) of sodium 4-nitro-4'-acetylamino-stilbene-2-sulphonic acid and 200 g of half-concentrated hydrochloric acid are heated to reflux until the starting material has been completely converted according to the thin-layer chromatogram.
After cooling, the product i5 filtered off with suction, washed neutral with small portions of water and dried. Yield: 14 g (88 %).

c~ 16 g (0.05 ~) of 4-nitro-4'-aminostilbene-2-sul-pho~ic acid (Example 6b) are suspended in 400 ml of ~ater, and 40 ml of concentra~ed hydrochloric acid are added~ Diazoti~ation is carried out by dropwise addition of 12.8 ~1 of 30 percent strength of sodium nitrite solution (0.0~ M + 10 %~ at a maximum of 13C, and ~tirring i~ then co~tinued at about 20C
Le A 26 260 - 33 ~-X~ 4 overnight. The nitrite excess is then des~royed by addition of sulphamic acid.

The diazonium salt solution obtained is added dropwise to a solution of 17.2 g (0.05 M) of 1-hydroxy-6-benzoylaminonaphthalene-3-sulphonic acid in 160 ml of water at about 20C, during which the pH is kept in the range from 7 to 8 by dropwise addition of sodium hydroxide solution. After stir-ring o~ernight, the precipit~ted dyestuff is fil-tered off with suction, washed neutral with a small amount of water and dried. Yield: 27 g (80 ~).

This gives a dyestuff of the structure:
OH
02N ~ H-CH ~ N=

H03S NH-C ~

Exastly analogously as described above, an analogous dyestuff is obtained by replacing l-hydroxy-6-benzoylaminonaphthalene-3-sulphonic acid by 1-hydroxy-6-anilinonaphthalene-3-sulphonic acid.

Further suitable coupling components are the ones mentioned in the ~ables of Examples le and 2c.

d~ If the nitro group of the 4-nitro-4'-acetylamino-~tilbene-2-sulphonic acid obtained according to a) is reduced in aqueous ethanol with sodium sulphide or analogously to the procedure in DOS (German Patent Specification~ 3,805,513, Example 3, 4-~mino-4'-acetyl~minostilbene-2-sulphonic acid is obtained.

Exactly analogously, it is also possible ~o prepare Le A 26 260 - 34 -z~

4-amino-4'-benzoylaminostilbene-2-sulphonic acid.

e) Diazotization of 4-amino-4'-acetylaminostilbene-2-sulphonic acid in accordance with the procedure of Example 6c, destruction of the nitrite excess with S sulphamic acid, and coupling of the product onto 1-hydroxy-6-benzoylaminonaphthalene-3-sulphonic acid, while maintaining a pH of 7-8, gives a dyestuff of the structur~.

~3'ri H~, ~H-C!~_~ti-N~
S O ~ H /~\ ,~`~, Y.O3S ,~U-CO--,~, The corresponding dyestuff which has a benzoylamino group on the stilbene radical is obtained analogously.

The other compounds mentioned in Examples le and 2c can also be used as further coupling components.

Exampla 7 a) At a maximum temperature of 10C, a solution of 7.8 g (0.05 M) of 2,5-dimethoxyaniline in 125 ml of water (to which concentrated hydrochloric acid is added until a clear solution is formed) is added dropwise to the diazonium salt solu~ion prepared according to Example 6c, with stirring, while maintaining a pH of 3 to 4.5 by metering in sodium hydroxide solution. After stirring overnight, during which the tempexature is allowed to rise to room temperature, the coupling reaction is completed. The product i8 filtered off with suction and carefully washed neutxal with water.

Le A 26 260 - 3~ -: ~, 4~4 Instead of 2,5-dimethoxyaniline, it is also possible to use 2=methoxy-5-methylaniline, 2,5-dimethylanili-ne, 3-methylaniline, 3-acetylaminoaniline, 1-naph-thylamine, l-amino-2-ethoxynaphthalene-6-sulphonic acid or anilinomethane sulphonic acid etc.

b) The intermediate obtained in a) is diazotized in the form of a paste in aqueous hydrochloric acid with sodium nitrite, the diazotization being allowed to go to completion by standing overnight and warming to room tempeature. Excess nitrite is destroyed by means of sulphamic aci~.-The diazonium salt solution is coupled onto 1-hydroxy-6-anilinonaphthalene-3-sulphonic acid at pH
6.5 to 7.5. The dyestuff obtained has the formula O~H3 OH
H-CH~ N ~ ~ N=:

~O35 NH

It is also possible to use the other compounds mentioned in Examples le and 2c as components of the end coupling.

The same dyestuffs are obtained by following the procedure in EP 160,113, ~xcept that the sodium 4-nitro-4'-aminostilbene~2,~'-disulphonate used there is replaced by 4-nitro-4'-aminostilbene-2-sulphonic acid and the middle component (2-methoxy-5-methyl-aniline) is chosen accordingly.

e A 26 260 - 36 -- .

4~L

Example 8 a) The dyestuff of Exzmple 6c which still contains a nitro group is reduced in an ethanolJwater mixture with sodium sulphide or analogously to the procedure in DOS (German Patent Specification) 3,805,513, Example 3, to the amino compound. Another possible reduction is that using iron powder in weakly acidic aqueous medium according to Bechamp.

b) 16.1 g (0.025 M) of the dyestuff obtained in a) are suspended in 300 ml of water, 20 r.l of concentrated hydrochloric acid are added and the mixture is dia-zotized by dropwise addition of 6.4 ml of 30 per cent strength sodium nitrite solution (0.025 M +
10~) at a maximum of 10C, and stirrin~ is allowed to continue overnigh~ at room temperature. The nitrite excess is then destroyed by addition of sulphamic acid.

The diazonium salt solution obtained is added dropwise to a solution of 8 g ~0.025 M) of l-amino-B-hydroxynaphthalene-2,4-disulphonic acid in 80 ml of water at about 20~C, while maintaining the pH at about 7. After stirring overnight, the precipitated dyestuff is filtered off with suction, washed with a small amount of water and dried. The dyestuff obtained has the ~tructure:
R -.N-N ~ H-CH ~ N=N-R

N~2 ~ OH
3~0~5~ ~Q

I HO35 NH-CO-~=~/
s~3~

Le A 26 260 - 37 -It is also possible to use the other compounds mentioned in Examples le and 2c as coupling components.

Example 9 a) 5 g tabout 0.05 M) of phenol are dissolved in 100 ml of water with the addition of sodium hydroxide solution, until ~ clear solution has been o~tained, and the diazonium salt solution obtained in Example 6c is then added dropwise at about 10C, during which a pH of about 9 is maintained by addition of sodium hydroxide solution. After stirring overnight, the mixture is neutralized, the precipitate filtered off with suction and washed.

The moist paste is reacted analogously to the procedure in Example 4c in aqu~ous alkaline solution lS with dimethyl sulphate, until complete methylation has taken place. This gives a dyestuff of the structure:

~o ~ H=CH ~ N=N~ CH3 so3~

Analogously, it can also be reacted with other - alkyla~ing agentsl for example diethyl sulphate or benzyl bromide.

b) The dyestuff obtained in a) is reduced with sodium ~ulphide in ethanol and water or with iron powder in weakly acidic medium to the amine. This amine is diazotized analogously to Example 6c with sodium ~5 nitri~e, and excess nitrite is then destroyed by means o~ sulpharnic acid.

Le A 26 ?60 - 38 -The dia~onium salt solution obtained is coupled in accordance with the further procedure in Example 6c onto l-hydroxy-6-benzoylaminonaphthalene-3-sulphonic acid at a pH between 7 and 8, which gives a dyestuff S of the formula below:

r,y 3 -O~N=N~H=CH~N=N
S O ~H /~\
. .C 35 NH ~

It is also possible to use the other compounds mentioned in Ex~mples le and 2c as componenLs of end coupling, in particular acetyl I acid, phenyl I acid, Chicago acid SS
etc.

Example 10 a) 4-amino-4'-nitrostilbene-2-sulphonic acid The compound is pxepared by claavage of the 4-acetylamino compound analogously to Example 6b described in DOS IÇerman Patent Specification) 3,805,513, Example 2ter.:

- b) Diazotization of the amino compcund prepared in 10a, followed by coupling of the product onto l-hydroxy-6-anilinonaphthalene-3-sulphonic acid analogously to the procedure in 6c gives the following dyestuff:

OH
2 N~3~ H = C H~3N = ~
SO~H NH

Le A 26 260 - 39 -Further suitable coupling components are ~he ones mentioned in the Tables of Examples le and 2c.

The dyestuffs which are isomers with respect to the position of the sulpho group are obtained analogous-ly by following the procedures of Examples 6 to 9;
these dyestuffs have exactly analogous hues.

Condensation dvestuffs Example 11 If the procedure of the examples in Houben-Weyl, Methoden der Organischen Chemie (Methods of organic chemistry~, Vol. 10/3, Part 3, P. 343 are followed and 1,2-bis(4-nitro-2-sulphophenyl)ethylene is replaced by 4,4'-di-nitrostilbene-2-sulphonic acid prepared according to DOS
(German Patent Specification) 3,805,513, Example 2, mainly the yellow condensation product of the formula:

R-N=N ~ CH=CH ~ N=N-R

R = H035 ~ N=N ~

is obtained analogously to the description found there.

The reaction of 4-amino-4'-nitrostilbene-2,2~-disulphonic asid descr~ed in J. Org. Chem. USSR 16 (1980) 388 is applied to the monosulphon~c acid:

Le A 26 260 - 40 -, ~ " , - 2~

a) 25 g (0.1 M) of copper ~2) sulphate pentahydrate are dissolved with heating in 80 ml of water, and 15.5 g (0.15 M) of sodium bromide are added. A solution of 6.3 g (O.05 M) of anhydrous sodium sulphite in 20 ml of water are slowly added to the solution with stirring. After cooling, the precipitate is separa-ted off by decanting, washed with water and then dissolved in 40 ml of concentrated hydrobromic acid.

24 g (O.075 M? of the amine of ~xample 6b are diazotized analogously to the procedure of Example 6c, except that ny~robromic acid is added inst~ad of hydrochloric acid. The diazonium salt solution is then stirred into the previously prepared above Cu salt solution at 0C with stirring. The mixture is carefully heated, which leads to the formation of the SANDMEYER product with evolution of nitrogen.
After the evolution of gas h~s stopped, the result-iny bromine compound of the structure:

02N ~ CH=Cff ~ 3 Br is precipitated by salting out, filtered off with suction, washed and dried.

Exactly ~nalogously, it is also possible to prepare the corresponding chlorine compound or the cyanide instead of the bromine compound.

If the amine of Example lOa is used instead of the amine of Example 6b and hydrochloric acid is used instead of hydrobromic acid, the following compound is obtained analogously:

_e A 26 260 - 41 -"

o2N~3CH=C!~ 1 b) The compound of Example 12a is reduced analogously to the procedure in Example 9b to the amino com-pound. This compound is converted into the corres-ponding diazonium salt, for example as described in 6c, and then as also described in 6c, coupled onto l-hydroxy-6~benzoylaminonaphthalene-3-sulphonic acid, while maintaining a pH of about 7-8. This gives the dyestuff of the structure:

OH
Br~H=CH~3N=`: ,~^q HO 3S !`IH - C ~3 .
Further suitable coupling components are those mentioned in Tables le and 2c.

c) If the procedure of Example 7 is repeated and the diazonium salt solution prepared in 12b is used instead of that used in 7a, and the product is first coupled onto 3-methylaniline and ~hen onto 1-1~ hydroxy-6-anilinonaphthalene-3-sulphonic acid, a dyestuff of the structure:

OH
B r~;3~H = CH~3N ~ N~;3N = ~

S03H HO ~S Nlt~2 is obtained. _==, Le A 26 260 - 42 -~36~4 Further suitable coupling components are those mentioned in Tables le and 2c.

Instead of 3-methylaniline, it is also possible to use2,5-dimethoxyaniline,2-methoxy-5-methylaniline, 2,5-dimethylaniline, 3-acetylaminoaniline, l-naph-thylamine, l-amino-2-ethoxynaphthalene-6-sulphonic acid or anilinomethanesulphonic acid etc.

d) If the corresponding chlorine or cyano compound is used in 12b and c) instead of the bromine compound from 12a, analogous dyes~C r~ are obtained.

E~ample 13 Analogously to the procedures in Houben-Weyl, Methoden der Organischen Chemie ~Methods of Organic Chemistry), Vol. 10/3, Part 3, p. 428, 429, the compound of the following formula is obtained ~y coupling of diazotized -~-amino-4'-nitrostilbene-2'-sulphonic acid, see Example ~b, on~o l-aminonaphthalene-4-sulphonic acid:

~2N~;~H~CH~3 N~

SO~H

I~is reduced analogously to the procedu.re of Example 12b to the amino compound.

The compound which is an isomer with respect to the position of the sulpho group is obtained ~nalogously by coupling onta 2-aminonaphthalene-6-sulphonic acid, followed ~y reduc~ion to the amino compound.

b) ~he amino compound prepared in a) is diazotized Le A ?6 260 - 43 according to -the procedure in Example 6c, and the product is coupled as described there onto 1-hydroxy-6-anilinonaphthalene-3-sulphonic acid, This gives a dyestuf f of the structure:
R-N=N ~ H-CH-~

OH

R = ~ NH ^`,-' ~ \
so3H

R = ~ ~

Analogously, the use of-2-aminonaphthalene-6-sulphonic acid give the isomeric dyestuff in which R' is ~ ~ -N
~50 3H

~xample 14 Light-polarizing sheets having similar good dichroic properties are obtained by replacing in Example 1 Mowiol~
~8-99 by Mowiol~ 40-88 (hydxolyzed polyvinyl ~cetate;
d2gree of hydrolysis 87.7 ~ 1.0 mole ~, viscosity of the 4~ strength aqueous solutio~ at 20C: 40 + 2.0 mPa.sec2 from ~oechst AG) or ~y ~owiol~ 4-98 (hydrolyzed polyvinyl acetats; degree of hydrolysis 9~.4 ~ 0.4 mole ~, visco-~ity of the 4% strength aqueous solution at 20C:

4~

4 i 1.0 mPa.sec2; from Hoechst AG) or by Mowiol~ 66-100 ~hydrolyzed polyvinyl acetate; degree of hydrolysis 99.7 + 0.3 mole %; YiSCosity of the 4% strength aqueous solution at 20C: 66 + 4.0 mPa.sec2. from Hoechst AG).

Exam~le 15 Analogously ~o Examples 1 and 14, light-polarizing sheets containing the dyestuffs from Examples 2-13 are pxoduced.
The sheets obtained are distinguished by good dichroic properties.

Le A 26 260 - 45 -

Claims (10)

1. Dyestuffs which, in the form of the free acid, conform to the formula in which X, Y signify -N=N-R, -CF3, -CONH2, -CONHR1, -CONR1R2, -COOH, -COOR1, -CN, -NO2, -NH2, -NHR1, -NR1R2, -OH, -OR1, -R1CONH-, -O-CO,-R1 halogen or a substituted or unsubstituted hetero-cyclic radical, with the proviso that at least one of the radicals X, Y reprPsents -N=N-R, in which R represents an aryl or a heterocyclic radical and R1, R2 represent alkyl, cycloalkyl, aryl or aralkyl, which may be interrupted by O and/or S, and in which furthermore the radicals mentioned for R, R1 and R2 can be substituted, the dyestuff which, in the form of its free acid, conforms to the formula I where and Le A 26 260 - 46 -being excepted and the azodyestuffs containing a maximum of eight azo bridges.

2. Dyestuffs of Claim 1 in which R is an aromatic radical of the benzol or naphthalene series, preferably of the formulae , in which R3 signifies H, OH, -OR1, -NH2, -NHR1, -NR1R2, -NH-COR1, -O-COR1, -N=N-R11, a heterocyclic radi-cal, R4, R5, R7, R8, R9, R10 signify H, halogen, -OH, -ORl, -NH2, -NHRl, -NR1RZ, R1, -SO3H, -SO2-NH2, -SO2-NHR1, -SO2-NR1R2, -O-CO-R1, -NH-CO-R1, R6 signifies H, -N=N-R11, a substituted or unsub-stituted heterocyclic radical and R11 -signifies a substituted or unsubstituted aryl radical, preferably a substituted or unsubstitu-ted phenyl or naphthyl radical or a substituted or unsubstituted heterocyclic radical or R is a nitrogen-containing heterocyclic radical.

3. Dyestuffs of Claim 2 where R, R11 denotes , in which R12 denotes -OH, -NH2 Le A 26 260 - 47 - R13 denotes H, if R14 = -N=N-R11 or H, and denotes -N=N-R11, if R14 = -OH, -NH2, R14 denotes -OH, -NH2, -N=N-R11, , , in which R15, R16 denote H, -OH, -OR1, -O-COR1, -NH2, -NH-R1, -NHR1R2, -NH-CO-R1, -SO3H, R17 denotes H, -SO3H.

4. Dyestuffs of Claims 1 and 2 in which R and R11 denote , , in which R18 denotes H, OH, NH2, -NH-CO-R1, -NH-R1, -N=N-R11, -SO3H, , Le A 26 260 - 48 -in which R19 denotes H, -N=N-R11, R20, R21 denote OH, NH2, -O-CO-R1, -NH-CO-R1, , ,

5. Dyestuffs of Claims 1 and 2 in which R or R11 denotes in which R22 denotes -NH-R1, -NH-CO-R1, -N=N-R11

6. Dyestuffs of Claims 1 and 2 in which R or R11 denotes a substituted or unsubstituted 5-amino- or 5-hydroxypyra-zole radical.

7. Dyestuffs of Claims 1 and 2 where R or R11 denotes where ?-(-A-N=N-)p-L
A is a substituted ot unsubstituted phenylene or naphthalene radical, L is a substituted or unsubstituted phenyl or naphthyl radical and P is 1, 2, 3 in paxticular those in which A denotes , and L denotes , Le A 26 260 - 49 -

8. Light polarizing films or sheets containing an organic polymer and a dyestuff or more than one dyestuff according to Claims 1 to 7.

9. Light-polarizing films or sheets according to Claim 8, containing an vinyl alcohol homopolymer or copolymer.

10. Light-polarizing films or sheets according to one or more of Claims 1-9, containing 0.01 to 10 % by weight, relative to the weight of the film, of a dyestuff accord-ing to Claims 1-7.

Le A 26 260 - 50 -