GB2048963A - In-line Colouration of Acrylic Fibres Using Bis-cationic Anthraquinone Dyes and Dyestuff Solutions Suitable Therefor - Google Patents

Abstract

The process is for the colouration of wet-spun acrylic fibres and comprises contacting the fibres while they are in gel condition with a bis cationic anthraquinone dyestuff free from acidic water-solubilising groups which has the formula (I): <IMAGE> in which Z is optionally substituted alkylene, Q<+> is a cationic group, A<-> is an anion, the floating -NH-Z-Q<+> group is in the 4-, 5- or 8-position of the anthraquinone nucleus and the benz rings A and B are optionally substituted. Aqueous dyestuff solutions which contain from 5 to 80% by weight of a dyestuff of formula (I) are used for this process. A preferred dyestuff has the formula (III): <IMAGE>

Description

SPECIFICATION 'In-line' Colouration of Acrylic Fibres Using Biscationic Anthraquinone Dyes and Dyestuff Solutions Suitable Therefor This invention relates to the colouration of acrylic fibres using certain bis cationic anthraquinone dyes. More particularly it relates to the colouration of such fibres while in a gel condition during a fibre-forming process. The invention also relates to novel solutions of certain bis cationic anthraquinone dyes for the colouration of acrylic fibres and to their manufacture.

It has long been known to dye acrylic fibres with cationic dyestuffs, including cationic anthraquinone dyestuffs, which are free from acidic water-solubilising groups. However, bis cationic anthraquinone dyes have been found to be unsuitable for dyeing pre-made acrylic fibres because of their low affinity and poor build up properties (see, for example, US Patent Specification 3646072). The use of certain bis cationic anthraquinone dyes for the dyeing of acid-modified nylon, acetate, silk and human hair has been disclosed in, for example, US Patent Specifications 3700398,3646072, 3904660,2153012 and 3467483.

It is also known to dye acrylic fibres that have been spun from certain aqueous salt solutions while they are in the form of a gel structure prior to being irreversibly dried. This process of dyeing wet-spun acrylic fibres while they are in a gel condition is fully described in, for example, UK Patent Specifications 991,957,992,195 and 1,Q56,731. Dyes which up till now have been found suitable for use in this so-called 'in-line' dyeing process are those cationic dyes which have proved suitable for dyeing pre-made acrylic fibres by other conventional dyeing techniques.

According to the present invention we provide a process for the colouration of wet-spun acrylic fibres which comprises contacting the fibres while they are in a gel condition with a bis cationic anthraquinone dyestuff free from acidic watersolubilising groups, such as sulphonic acid and carboxylic acid groups, which has the formula (I)

in which Z is optionally substituted alkylene, Qs is a cationic group, As is an anion, the floating --NHH--Z-Qo group is in the 4-, 5- or 8-position of the anthraquinone nucleus and benz rings A and B are optionally substituted.

In using the term acrylic fibres we include polymers and copolymers of acrylonitrile and dicyanoethylene.

As has already been said, processes for the 'inline' colouration of wet-spun acrylic fibres in a gel condition are already known and documented in patent literature. Any such process can be used with the present invention. Technicians skilled in operating these processes will readily be able to substitute known dyestuffs already used in these processes for dyestuffs of formula (I) if they are in a suitable form. Most suitable are aqueous solutions of the dyestuffs.

Thus in another aspect of our invention we provide a dyestuff solution comprising from 5 to 80% preferably from 10 to 60% and especially from 30 to 50% by weight of a dyestuff of formula (I) in an aqueous medium. The invention also includes a process for preparing these solutions.

Generally the dyestuffs of formula (I) are highly soluble, more so that their mono-cationic counterparts, and it is therefore possible to obtain concentrated solutions in water without solubilising aids. Nevertheless, it may be desirable to include these depending on, for example, the anion chosen which is not without effect on the solubility of the dye. Aids to improve the storage stability of the solution may also be usefully added.

It is intended therefore that the solutions of the invention may contain the various additives and auxiliaries commonly used in preparing aqueous solutions of cationic dyes such as those described in UK Patent Specification 1333937. These include water-soluble organic bases and carboxylic acids, neutral water-soluble organic solvents and various other auxiliaries and surfactants.

In particular we would mention the use of liquid polyhydric alcohols and carboxylic acids as stabilising aids. Both may be used together or without the other.

Examples of suitable polyhydric alcohols are ethylene glycol, diethylene glycol, triethylene glycol, 1 ,2-propylene glycol and glycerol. If used, these will normally be present in amounts of from 5 to 50% by weight of the solution. The inclusion of ethylene glycol in amounts of from 10 to 15% by weight of the solution is especially to be mentioned.

Suitable carboxylic acids include optionally substituted carboxylic acids having 1 to 4 carbon atoms. Examples are formic, acetic, propionic, butyric, glycollic, chloracetic, lactic and tartaric acids, of which acetic acid is of particular value. If used, the carboxylic acids will normally be present in the amounts mentioned for polyhydric alcohols.

The dyestuff solution is readily prepared by dissolving the appropriate quantity of a powder or paste of the chosen bis-cationic anthraquinone dye of formula (I) in water or if a solvent is used, in either the water or solvent or any combination of these. In order to aid dissolution the liquids may be warmed to, say, 40 to 500C if necessary.

Alternatively, the solution is obtained by diluting, as appropriate, the reaction mixture in which the dyestuff is made. It will not be uncommon for the dyestuff to be made in polyhydric alcohol, especially ethylene glycol, in which case the dyestuff solution can be prepared simply by dilution with water. If the dyestuff is made in water, optionally in the presence of a surfactant, further water is added as necessary together with, for example, a polyhydric alcohol or carboxylic acid to stabilise the solution is required.

The surfactant present in the dyestuff reaction mixture may be, for example, a cationic surfactant or a surfactant of the betaine type such as Empigen BB (Empigen is a registered trade mark).

In the dyestuffs of formula (I), benz rings A and B may carry any of the substituents commonly found in anthraquinone dyes. These include hydroxy, lower alkyl and halogen, especially bromine and chlorine.

Z may be branched or unbranched alkylene and may carry substituents which include hydroxy and halogen, especially chlorine.

Preferably the floating --NHH--Z-QO group is in the 4-position of the anthraquinone nucleus.

The cationic group Q0D is suitably a cyclammonium group such as pyridinium, a quaternary ammonium group which may be, for example, trialkylammonium, especially trimethylammonium, an isothiouronium group, for example,

a hydrazonium group, for example,

or a sulphonium or phosphonium group. Such cationic groups are well known in cationic dye technology and are more particularly described in, for example, our UK Patent Specification No.

1482234.

The anion AO may be inorganic or organic in character and may be any of those anions commonly used in the cationic dye field. lots nature is not of importance with respect to the tinctorial properties of the dye and will normally be selected on solubility grounds.

Examples of suitable organic anions are acetate, methosulphate, and p-tolyisulphonate and of suitable inorganic anions chloride, bromide, iodide, bisulphate, sulphate, sulphamate, phosphate and borate. Most conveniently the tetrachlorozincate is used. In those cases where the anion is polyvalent the water soluble dyestuffs will contain a corresponding molar proportion of the cationic moiety.

When we use the term "lower" to describe an alkyl containing group, we mean that the alkyl moiety has from one to four carbon atoms.

Of particular interest to us are the dyestuffs free from acidic water-solubilising groups which have the formula (II)

in which X and X1 are each independently hydrogen or hydroxy, R1, R2, and R3 are each independently hydrogen, optionally substituted lower alkyl, cycloalkyl, aryl, or aralkyl or two of R1, R2 and R3 together with the nitrogen atom to which they are attached form a 5- or 6-membered heterocyclic ring, such as morpholino, pyrrolidino or piperidino, or R1, R2 and R3 together with the nitrogen atom to which they are attached form a cyclammonium ring, such as pyridinium and picolinium, and AO has the meaning hereinbefore defined.

Substituents which may be carried by lower alkyl or cycloalkyl include cyano, hydroxy lower alkoxy, halogen and lower alkoxy carbonyl.

Cycloalkyl includes 5 to 7 membered carbocyclic rings. Aryl includes phenyl and aralkyl includes phenyl lower alkyl especially benzyl. Substituents which may be present in aryl and aralkyl include lower alkyl, lower alkoxy, halogen, cyano, lower alkyl carboxyl, lower alkoxy carbonyl, N,N-dilower alkyl substituted carbonamido and acylamino.

Of especial interest are the dyestuffs of formula (II) in which X and X' are hydrogen and R1, R2 and R3 are lower alkyl, especially methyl.

The dyestuffs which are used in the invention are conveniently prepared, for example, by condensing a compound of the formula

wherein X1, R, and R2 have the meaning hereinbefore defined, with a leuco-1 ,4,5,8- tetrahydroxyanthraquinone or with a mixture of a quinizarin and the corresponding leuco- quinizarin, as appropriate, and quaternising the disperse dye so formed.

The condensation reaction is conveniently carried out in an aqueous, aqueous/organic or organic medium mixture of equal parts of an alcohol, e.g. ethanol, and water is quite suitable and preferably in an atmosphere free from oxygen. In most cases the reaction can be completed at a temperature of 70-900C within two to four hours without the need of a copper catalyst.

In the case of the quinizarin condensation, unwanted yellow leuco dye is removed by adding to the reaction mixture small quantities of sodium m-nitrobenzene sulphonate and piperidine and stirring the mixture at the same temperature for a further two hours or so.

Suitable quaternising agents which can be used to introduce the R3 group and form the cationic moiety include alkyl halides such as methyl iodide, ethyl iodide or ethyl bromide, cycloalkyl halides, aralkyl halides such as benzyl chloride, alkyl sulphates such as dimethyl sulphonate, diethyl sulphate and diisopropylsulphate and aryl sulphonic esters such as methyl, ethyl and butyl p-toluene sulphonate.

The intermediate disperse dye may be isolated and then quaternised in an inert organic solvent such as benzene, toluene, xylene, chlorobenzene, nitrobenzene, acetone, carbon tetrachloride, tetrachlorethane or pi-ethoxyethancl. In certain cases it is possible to use a medium consisting of the quaternising agent or of water or an aqueous organic solvent. Conveniently the cationic dyestuff can be directly obtained in solution by quaternisation of the disperse dye reaction mixture. The alkylating agent is preferably used in considerable molar excess of the dyestuff.

Suitable temperatures for alkylation are from 20 to 1 500C and will vary according to the medium chosen.

When the alkylation is effected in organic solvents the intermediate dyestuff, which is normally insoluble, is conveniently isolated by filtration, purified by dissolution in warm water, precipitated by salting out as, for instance, a double salt with e.g. zinc chloride and finally isolated.

The dyestuff of especial interest to the applicants having the formula (it1):

is similar in shade to Cl Basic Blue 22 but has the commercial advantage that it is significantly cheaper and easier to make.

The invention is illustrated by the following Examples in which all parts and percentages are by weight unless otherwise specified. Where parts by volume are given, the relationship of weight is the same as that between gram and millilitre.

Example 1 Preparation of Dyestuff A mixture of 16 parts of quinizarin, 8 parts of leucoquinizarin, 60 parts by volume of ethanol, 60 parts by volume water and 25 parts of y-N,Ndimethylaminopropylamine are stirred under nitrogen at 80-850C for 4 hours. Analysis by thin layer chromatography indicates that complete reaction has occurred.

5 parts of sodium m-nitrobenzene sulphonate and 1 part by volume of piperidine are added to the reaction mixture and stirring continued at 80-850C for a further 2 hours until no yellow leuco dye can be detected by thin layer chromatography.

The product is isolated by the addition of acetic acid and zinc chloride and the excess amine removed by steam distillation.

8.16 parts of the disperse dye so obtained are dissolved in 50 parts by volume of chlorobenzene and stirred at 600.2.5 parts of dimethyl sulphate are added to the blue solution and the resulting mixture stirred for half an hour at 600. A copious precipitate of a dark blue solid forms.

After cooling the reaction mixture to 250C, the violet coloured chlorobenzene liquors are decanted off and the residual dark blue solid dissolved in warm water. The solution is filtered through "Hyflo Supercel" and the product isolated from the filtrate by the addition of 100% zinc chloride solution. The resulting dyestuff which has the structure:

is tiltered ott and dried.

Preparation of Dyestuff Solution A concentrated solution of this dyestuff is prepared by dissolving 34% by weight of the dried dyestuff in water and sufficient glacial acetic acid to adjust the pH to 4.0 to 4.5 It is used to dye wet-spun polyacrylonitrile fibre in a gel condition by a method described as follows.

'In-line' Dyeing A spinning solution consisting of 10 parts of polyacryionitrile in 90 parts of an aqueous 60% by weight zinc chloride solution is pressed out into an aqueous coagulation bath containing 44% byweight of zinc chloride, whereby a bundle consisting of a great number of-fibres is formed, the bundle containing 5 to 6% by weight of water per part by weight of dry polymerisate in the hydrogel structure.

After being removed from the coagulating bath, the coagulated bundle is washed until free of salt by being passed through several consecutive water baths. It is then stretched wet at 950C in order to give the fibres a total stretched length which is 1 2 times greater than the original length after the pressing out process.

The bundle is passed through squeezing rollers to reduce the water content of the gel structure to about 200% by weight. The fibre bundle is afterwards treated in a dye bath containing 10% by weight of the dyestuff solution prepared above, the fibre bundle being passed round a guide roller through the bath, at a temperature of 20--400 (ambient temperature) for 1/20 sec. With 1/10 sec. retention time. The dyed bundle is then passed through a second set of squeezing rollers to remove excess dyestuff solution from the gel fibres, and finally transferred to a drying oven where the fibres are dried at 1 400C to give the final textile fibres.

The dyestuff colours the polyacrylonitrile fibre a bright blue shade: the dyed cloth exhibiting excellent fastness properties.

Example 2 The procedure of Example 1 is repeated except that the condensation stage is carried out in aqueous ethylene glycol. The condensation reaction proceeds equally efficiently.

Example 3 A solution of the dyestuff of Example 1 is made by a "through process" as follows, without isolation of an intermediate product.

A mixture of 1 ,4-dihydroxyanthraquinone (36 parts), I ,4-dihydroxy-2,3-dihydroanthraquinone (12 parts) and water (60 parts) is stirred at ambient temperature in a nitrogen gas atmosphere. 3-N:N-dimethylaminopropylamine (40.8 parts) is added dropwise to the mixture and the temperature raised to 80 C over one hour.

The temperature is maintained between 80 and 85"C for three hours when condensation is complete. The mixture is then cooled to between 35 and 40 C before dimethylsulphate (61 parts) is added over one hour. The mixture is stirred for a further hour to ensure complete methylation and then until residual dimethyl sulphate is destroyed.

Acetic acid (42 parts) is added and the solution screened to remove traces of insoluble matter.

Ethylene glycol (25 parts) is added as a humectant to the resulting solution.

"In-line" dyeing is carried out as in Example 1.

Example 4 The procedure of Example 1 is repeated except that benzyl chloride replaces dimethyl sulphate as the alkylating agent. The dyestuff obtained which has the formula:

colours polyacrylonitriie bright blue.

Claims (11)

Claims

1. Process for the colouration of wet-spun acrylic fibres which comprises contacting the fibres while they are in gel condition with a bis cationic anthraquinone dyestuff free from acidic water-solubilising groups which has the formula (1):

in which Z is optionally substituted alkylene, Qo is a cationic group, AO is an anion, the floating --NHH--Z-QO group is in the 4-,5. or 8-position of the anthraquinone nucleus and the benz rings A and B are optionally substituted.

2. A dyestuff solution for use in the process of claim 1 which comprises from 5 to 80% by weight of a dyestuff of formula (I) in an aqueous medium.

3. A dyestuff solution as claimed in claim 2 in which there is from 10 to 60% by weight of the dyestuff.

4. A dyestuff solution as claimed in claim 2 in which there is from 30 to 50% by weight of the dyestuff.

5. A dyestuff solution as claimed in any one of claims 2 to 4 in which there is present a polyhydric alcohol or carboxylic acid or both.

6. A dyestuff solution as claimed in claim 5 in which there is present ethylene glycol or acetic acid or both.

7. A dyestuff solution as claimed in any one of claims 2 to 6 in which the dyestuff has the formula (II)

in which X and X1 are each independently hydrogen or hydroxy, R1, R2, and R3 are each independently hydrogen, optionally substituted lower alkyl, cycloalkyl, aryl, or aralkyl or two of R1, R2-and R3 together with the nitrogen atom to which they are attached form a 5- or 6-membered heterocyclic ring, or R1, R2 and R3 together with the nitrogen atom to which they are attached form a cyclammonium ring, and Ao has the meaning given in claim 1.

8. A dyestuff solution as claimed in claim7 in which X and X' are hydrogen and R1, R2 and R3 are lower alkyl.

9. A dyestuff solution as claimed in claim 8 in which R1, R2and R3 are methyl.

10. A process as claimed in claim 1 substantially as herein described with reference to Examples 1 to 4.

11. A dyestuff solution as claimed in claim 2 substantially as herein described with reference to Examples 1 to 4.