GB1564722A

GB1564722A - Disperse dyestuff compositions

Info

Publication number: GB1564722A
Application number: GB3282/76A
Authority: GB
Original assignee: Imperial Chemical Industries Ltd
Current assignee: Imperial Chemical Industries Ltd
Priority date: 1976-01-28
Filing date: 1976-01-28
Publication date: 1980-04-10
Also published as: JPS5291976A; CH632888B; FR2339655B1; IT1076109B; CH632888GA3; FR2339655A1; DE2703594A1; ES455428A1

Abstract

Aqueous dispersions of a dispersion dye contain a dispersant mixture containing a) a fluorine-free surfactant and b) a surfactant with a terminal perfluoro group. Such dispersions, especially of hydrophobic dyes, are easily and uniformly dispersible in water and have little tendency to sediment and to form aggregates. They may be used for the preparation of dye baths and printing pastes for textile materials.

Description

(54) DISPERSE DYESTUFF COMPOSITIONS (71) We, IMPERIAL CHEMICAL INDUSTRIES LIMITED, Imperial Chemical House, Millbank, London SW1P 3JF, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to dyestuff compositions and more particularly to aqueous dispersions containing disperse dyestuffs.

Disperse dyestuffs are defined by the Society of Dyers and Colourists as " substantially water-insoluble dyes having substantivity for one or more hydrophobic fibres, for example cellulose acetate and usually applied from fine aqueous dispersion." They are also commonly applied to cellulose triacetate, nylon and polyester fibres and may also be used for surface dyeing of selected thermoplastics. For all such purposes they are marketed as concentrated solid or liquid compositions which contain surfactants. Fine uniform distribution of the dye throughout the dyebath is necessary in order to promote satisfactory even dyeing, and the marketed forms of the dyestuff comDositions need to be such that a uniform dy & ath can easily be prepared from them.

The surfactants hitherto used in disperse dye compositions comprise hydrocarbon structures to which a hydrophilic group is attached. We hereinafter refer to all such surfactants as "hydrocarbon surfactants".

Depending upon the nature of the hydrophilic group hydrocarbon surfactants may be anionic, cationic or non-ionic in character. As hydrophilic groups anionic surfactants may, for example contain sulphate, sulphonate, phosphonate or carboxylate groups: cationic surfactants may, for example, contain quaternary ammonium or phosphonium groups or tertiary sulponium groups and non-ionic surfactants may contain polyoxyalkylene chains e.g. polyoxyethylene or polyoxypropylene chains, or amine oxide groups.

According to the present invention there is provided an aqueous dispersion of a disperse dyestuff wherein the dispersing agent comprises a hydrocarbon surfactant as hereinbefore defined and a terminal perfiuoro surfactant.

To promote water-dispersibility the dyestuff in the composition is in finely divided form i.e. the particle dimensions are such as are common in dyebaths used for the application of disperse dyes to textile fibres. The particle dimensions may be for example less than 5 microns and more particularly from 3 to 5 microns.

Terminal perfiuoro surfactants comprised in the composition of the invention may be of the formula: R--XX-Y wherein Rf is a perfiuoro alkyl radical C, F1 wherein n is an integer greater then 2, X represents either a direct linkage or a divalent linking radical and Y is a hydrophilic group.

The perfiuoroalkyl radical Rf preferably contains from 5 to 12 carbon atoms. Specific examples of perfiuoroalkyl radicals Rf are the straight chain radicals C,F13, and CSFls and more especially the branched chain radicals Caff,, CloFl9 and Cl2F2s. The preferred branched chain radicals are of the formula C,,F,,~, where m is an integer greater than 3. Surfactants containing such perfluoro radicals are obtainable through processes which are described and claimed in our United Kingdom Patents 1,130,822 and 1,366,691.

The hydrophilic group Y may be of any character, such as may for example be present in hydrocarbon surfactants and are exemplified above.

The linking radical -X- may be a simple alkylene radical, for example, an alkylene radical containing from 2 to 6 carbon atoms or an arylene radical, for example, a phenylene radical but preferably linkage to the perfluoro radical Rt is through a hetero-atom, especially an oxygen atom present in the linking radical X. Thus the preferred linking radicals -X- are oxyalkylene, especially polyoxyalkylene, radicals, e.g. polyoxyethylene radicals (OC2H4)p where P is an integer from 3 to 40, preferably 10 to 25, and oxyarylene radicals e.g. the oxyphenylene radicals --OC,H,,-. Linkage with Rf may also be through a -CONH alkylene or -SO2 alkylene groups.

Specific examples of terminal perfluoro surfactants which may be present in the compositions of the invention are the compounds C,,F,,-(OCH,CH2)s'-OC.F1, wherein q has an average value of 11, 22 or 33 C,,0F10OC0H4SO3Na C,F1, CONH C2HsN(CH3)2 [C,F15 CONH C3H"N(CH3)3] ,+SO4= The preferred terminal perfluoro surfactant has the structure C8F2,-(OCH2CH2)23 OC0F12, the 23 oxyethylene units in this formula representing the average value of a mixture of compounds having oxyethylene chains of different lengths.

Only small proportions of the perfiuoro surfactants in addition to the hydrocarbon surfactants are needed in order to provide water dispersible compositions. Thus for example the dyestuff composition contains terminol perfluoro surfactants in weight percentage from 0.01% to 2.0% with respect to the dyestuff. Percentages less than about 0.1% are generally insufficient to obtain the full benefit of the invention, and percentages above 1.0% do not yield improvements commensurate with the further amounts added.

Thus the preferred range is 0.1 to 1.0% by weight of terminal perfluoro surfactant based on the weight of dyestuff.

The hydrocarbon surfactant may be any surfactant comprising a hydrocarbon structure to which a hydrophilic group is attached, which is known from the art or used in practice as a dispersing agent for disperse dyestuffs. Examples of suitable dispersing agents are the alkali metal, especially sodium, salts of naphthalene-2-sulphonic acid/formaldehyde condensates, the phenol/formaldehyde/ sodium sulphite/sodium hydroxide reaction product which is described in German Offenlegungsschrift 2401818, alkali metal, especially sodium, and ammonium salts of lignosulphonic acids, and the cresol/formaldehyde/ sodium sulphite reaction product described in FIAT Report No. 1013 dated 25.11.46 and known as "Dispierungsmittel SS".

In the case wherein the alkali metal salt of a naphthalene-2-sulphonic acid/formaldehyde condensate is used as the hydrocarbon surfactant, the aqueous dispersion may also contain poly (vinylpyrrolidone), conveniently added as an aqueous solution. The poly (vinylpyrrolidone) has a synergistic effect on this particular dispersing agent system.

The hydrocarbon surfactant may be present in amounts from 1% to 200% by weight based on the weight of dyestuff and preferably 10--100% by weight. It may be found that the amount of hydrocarbon surfactant required to obtain a satisfactory dispersion is less, by virtue of the presence of the perfluoro surfactant, than it otherwise would be.

The most desirable proportions of each additive are therefore a compromise between the technical effect (superior dispersion) obtained and the cost of the additives.

The amount of dyestuff present in the dispersions according to the present invention may be from 5 to 60% by weight based on the total weight of the dispersion, but in general will be from 15 to 30% by weight.

The aqueous dyestuff dispersion must contain water in sufficient quantity to provide a fluid composition. Thus, water may comprise from 25 to 90% by weight of the total weight of the dispersion, and preferably 25 to 50% by weight.

The invention is of particular value when the disperse dyestuff in the composition is hydrophobic is character, i.e. when it is of such a character that its surface is not easily wet by water. Disperse dyestuffs containing an alkyl chain of at least 4 carbon atoms are especially hydrophobic in character.

More particularly the disperse dyestuff in the composition of the invention may, in ope of its possible tautomeric forms, be represented by the formula:

wherein A is a phenyl radical which is substituted by a nitro, cyano, trifluoromethyl, -SO2R', -CONR4R', --COR3, or SO2NR4Rs groups and is optionally further substituted by one or two nitro, cyano, lower alkoxy, hydroxy lower alkoxy, acyloxy, lower alkyl or phenoxy groups; R3 is an alkyl, cycloalkyl, aryl or aralkyl radical; R4 is hydrogen, alkyl, cycloalkyl, aryl or aralkyl; R5 is hydrogen or alkyl; and Z may be alkyl or cycloalkyl either of which may optionally be substituted or it may be aryl optionally carrying substituents.

Such dyestuffs, and their manufacture, are described and claimed for example in our United Kingdom Patent No. 1,398,741 and Application No. 33718/73 (Serial No.

1452322).

The alkyl radicals represented by R3, R4 and R5 are preferably alkyl radicals containing from 1 to 10 carbon atoms such as methyl, ethyl, n-propyl, n-butyl, amyl, hexyl, octyl, dimethylhexyl and dodecyl radicals.

The cycloalkyl radicals represented by R3 and R4 are preferably cyclohexyl. The aryl radi cals represented by R3 and R4 are preferably monocyclic aryl radicals such as phenyl, tolyl and xylyl. The aralkyl radicals represented by Ra and R4 are preferably phenyl lower alkyl radicals such as benzyl and ,B-phenyl- ethyl radicals.

The designation "lower" means that the radical contains not more than 5 carbon atoms.

As examples of the hydroxy lower alkoxy groups there may be mentioned ,B-hydroxy- ethoxy and a-hydroxypropoxy. The acyloxy lower alkoxy groups are preferably lower alkyl carbonyloxy lower alkoxy groups such as t3-acetoxyethoxy.

The alkyl radicals represented by Z preferably contain at least 4 carbon and especially from 4 to 12 carbon atoms. Examples are butyl, amyl, hexyl, 2-ethyl-n-hexyl, octyl, decyl, dodecyl, and dimethylhexyl radicals.

Examples of cycloalkyl and aryl radicals which may be represented by Z are cyclohexyl and phenyl respectively.

The invention is of especial value when the dyestuff in the composition is of the above formula wherein the phenyl radical A is substituted by a group -SO2NR1R2 wherein R1 is a hydrogen atom or an alkyl, cycloalkyl, aralkyl or aryl radical, and R2 is an alkyl radical containing 5 or more carbon atoms; and the phenyl radical A may be further substituted by nitro, cyano, alkyl, alkoxy, chlorine, bromine, phenyl or phenoxy.

The alkyl radicals represented by R2 preferably contain from 5 to 12 carbon atoms such as n-amyl, n-hexyl, n-octyl, n-decyl, ndodecyl, 2-ethyl-n-hexyl and 1:1:3: 3-tetra- methyl-n-butyl radicals.

As an example of a cycloalkyl radical represented by Rl there may be mentioned cyclohexyl. As examples of aralkyl radicals represented by Rl there may be mentioned phenyl lower alkyl radicals such as benzyl and ,8-phenylethyl radicals. The aryl radicals represented by Rl are preferably monocyclic aryl radicals such as phenyl, tolyl and xylyl radicals. The alkyl radicals represented by Rl preferably contain from 1 to 12 carbon atoms such as methyl, ethyl, propyl, butyl, alkyl, nhexyl, n-octyl, n-decyl and n-dodecyl radicals, but are preferably lower alkyl radicals. Above all it is preferred that Rl is a hydrogen atom.

More specifically, the invention is of especial value when the pure dyestuff in the composition is of the formula

wherein Rl is hydrogen, and R2 and Z have the meanings previously stated.

A particularly preferred dyestuff is that in which R2 is the 2-ethylhexyl radical, the sulphonamide group being para to the azo linkage, and Z is the n-butyl radical.

The aqueous dyestuff dispersions of the invention may be manufactured by agitating in aqueous medium the dyestuff, terminal perfiuoro surfactant and hydrocarbon surfactant containing a hydrophilic group in the presence of particulate grinding elements, for example pebbles, hard spheres, coarse sand or gravel. Advantageously, undried press pastes from the manufacture of the dyestuff may be used directly in the agitating process.

When a dispersion of sufficient fineness has been produced the grinding elements are removed. The resultant liquid dispersion may then be used as such or if desired it may be dried by known techniques which avoid reaggregation of dispersed particles, for example by spray drying or freeze drying.

The aqueous dyestuff dispersions of the invention are valuable for the preparation of dyebaths or printing pastes from which the disperse dyestuffs may be applied to textile materials in known manner. They are also useful for incorporating the dyestuffs into aqueous printing inks.

The aqueous dyestuff dispersions may if desired contain a water-miscible organic liquid, preferably a polyhydric alcohol, as a humectant and/or to prevent freezing of the dispersion when it is exposed to low tem- peratures such as may occur when a dispersion is stored in the open in cold weather.

Suitable compounds for this purpose are, for example, ethylene glycol and glycerol. Such additives may be present in amounts up to 50% by weight based on the aqueous phase and dependent on the degree of protection required.

The dispersions may also contain preservatives to protect them from attack by microorganisms. A suitable preservative is, for example, the sodium salt of orthophenyl phenol.

Preservatives may be used in amount of 0.01 to 0.5% by weight based on the total weight of the dispersion.

Compared with comparable compositions in which only hydrocarbon surfactants are used, the aqueous dispersions of the invention, especially those containing hydrophobic dyes and more particularly the dyestuffs hereinbefore indicated by formulae, are more easily and uniformly dispersed in water, and the compositions have less tendency to settle and aggregate.

Example 1.

This example relates to the making of a liquid, containing a hydrophobic dye and a dispersing agent, intended for the dyeing of polyester fibre in conventional dyebaths.

53.40 Parts of a yellow dyestuff paste con taining 29.00 parts of the dye obtained by diazotising 4 - aminobenzenesulphon - N (2 - ethylhexyl) - amide and coupling with 1 - n - butyl - 3 - cyano - 6 - hydroxy - 4methylpyrid - 2 - one was mixed with 17.40 parts of a hydrocarbon dispersing agent prepared by heating phenol, formaldehyde, sodium sulphite and sodium hydroxide in an autoclave as described in Example 1 of German Offenlegungsschrift 2401 818, 2.0 parts of a 10% aqueous solution of a terminal perfluoro surfactant of the formula C0F15 (OCH2CH2 ),8OC,F15 as hereinbefore defined, 1.75 parts of a 20% aqueous solution of the sodium salt of orthophenyl phenol and 12.96 parts glycerol.

The pH was adjusted from 10.9 to 7.8 by adding acetic acid. This mixture was agitated with 333 parts of particulate grinding elements in a mill fitted with discs rotating at 3000 rpm. After 30 minutes a quantity of 20% aqueous glycerol was added to bring the final composition to 26% colour, 15.6% agent5 0.31 % sodium salt of orthophenylphenol - the balance being 20% aqueous glycerol. After a brief mixing the mill charge was separated from the grinding elements to yield approximately 71 parts of liquid.

Comparative Example.

A comparative product was made by following the procedure of Example 1 omitting the terminal perfluoro surfactant.

The two products were separately dispersed by stirring 6 parts into 150 parts of water and the apparently homogeneous dispersions tested after dividing into three equal aliquots. The first was heated rapidly to 400C and filtered through two No. 4 Whatman filter papers. The second and third aliquots were similarly treated being heated at the boil for 10 and 30 minutes respectively. The deposit left on the filter paper was then examined with the following results:-

40 C 10 min. boil 30 min. boil Comparative Trace Trace + many Small amount Example large specks Example I Trace Trace Trace The products were further tested by dyeing texturised polyester yarn using a minature laboratory package dyeing machine. At 2% depth of shade dyed at 1300C for 45 minutes, followed by a cold water rinse (no reduction clearing treatment) the product of Example 1 gave less dyebath deposit than that of the Comparative Example and the dyeing from the Example 1 product had better fastness to rubbing.

Example 2.

This example relates to the making of a fluid aqueous paste containing approximately 40% by weight of dye, suitable for milling to make a printing paste ingredient To 552 parts of water were added 21 parts of a 38% aqueous solution of the sodium salt of a condensate of naphthalene e-sulphonic acid and formaldehyde, 27 parts of a 30% aqueous solution of polyvinylpyrrolidone and 0.5 parts of a terminal perfluorosurfactant of the formula CsFzs(OCH2CH2)2sOC8FX6, which is a synergistic dispersing agent system, followed by mixing using a Silverson mixer/ homogeniser. 400 Parts of 1,4-dimethylamino-anthraquinone (a disperse dye of hydrophobic character) were added to the stirred mixture uniformly over a period of one hour. A fluid dispersion was obtained.

In a similar procedure carried out in the absence of perfluorosurfactant it was not possible to incorporate the dye even after 5 hours mixing because the dye was not completely wetted by the mixture.

Example 3.

The procedure described in Example 2 was repeated except that the 400 parts of 1,4 - dimethylaminonanthraquinone were replaced by 400 parts of 1 - hydroxy - 4 anilinoanthraquinone. A similar result was obtained.

1 - Hydroxy - 4 - anilinoanthraquinone is an extremely hydrophobic dyestuff and was not wetted out in 7 hours in the absence of the perfiuoro surfactant.

Example 4.

This example relates to the making of an aqueous dispersion containing a hydrophobic dye and a dispersing agent, intended for the dyeing of polyester fibre in conventional dyebaths.

74.4 Parts of a yellow dyestuff paste, containing 48.0 parts of the dye obtained by di- - azotising 4 - aminobenzenesulphon - N - (2ethylhexyl)amide and coupling with 1 butyl - 3 - cyano - 6 - hydroxy - 4 - methylpyrid - 2 - one, was mixed with 19.2 parts of Reax 85 (a sodium lignosulphonate; "Reax" is a Registered Trade Mark), 3.2 parts of a 10% aqueous solution of a terminal perfluoro surfactant of the formula: CgF15(OCH2CH2)25OC,F155 1.9 parts of a 20% aqueous solution of the sodium salt of o-phenylphenol and 10.4 parts of glycerol.

The pH of the mixture was adjusted from 10.5 to 7.9 by the addition of 20% aqueous aqueous acetic acid, and the mixture was agi tated with 333 parts of particulate grinding elements in a mill fitted with discs rotating at 3000 rpm. After 30 minutes a quantity of 20% aqueous glycerol was added to bring the final composition to 40% colour, 16% Reax, 0.27% perfluoro surfactant, 0.31% sodium salt of o-phenylphenol, the remainder being 20% aqueous glycerol. This product was satisfactory for the high temperature dyeing of polyester yarn at 1300C as described in Example 1.

WHAT WE CLAIM IS: 1. An aqueous dispersion of a disperse dyestuff wherein the dispersing agent comprises a hydrocarbon surfactant which is a hydrocarbon structure to which a hydrophilic group is attached, and a terminal perfluoro surfactant.

2. A dispersion as claimed in claim 1 wherein the particle dimensions of the disperse dyestuff are from 3 to 5 microns.

3. A dispersion as claimed in claim 1 or claim 2 wherein the terminal perfluorosurfactant is of the formula RI--XX-Y, wherein Rf is a perfluoro alkyl radical C,,F1 wherein n is an integer greater than 2, X represents either a direct linkage or a divalent linking radical and Y is a hydrophilic group.

4. A dispersion as claimed in claim 3 wherein the radical R, contains from 5 to 12 carbon atoms.

S. A dispersion as claimed in claim 3 wherein the radical R, represents a branched chain radical of the formula C H4an~1 where m is an integer greater than 3.

6. A dispersion as claimed in any one of claims 3 to 5 wherein X is a polyoxyethylene radical containing from 3 to 40 oxyethylene units or an oxyphenylene radical, the radical Rf being attached to a terminal oxygen atom thereof.

7. A dispersion as claimed in claim 6 wherein the number of oxyethylene units in the polyoxyethylene radical is 10 to 25.

8. A dispersion as claimed in claim 1 or claim 2 wherein the terminal perfluoro surfactant has the structure C,F,,(OCH2CH,)28OC,F1, in which the 23 oxyethylene units represents the average value of a mixture of compounds having oxyethyl- ene chains of different lengths.

9. A dispersion as claimed in any one of claims 1 to 8 which contains from 0.1 to 1.0% by weight of the terminal perfiuoro surfactant with respect to the disperse dyestuff.

10. A dispersion as claimed in any one of Claims 1 to 9 wherein the hydrocarbon surfactant is present in an amount from 1 to 200% by weight based on the weight of disperse dyestuff.

11. A dispersion as claimed in claim 10 wherein the amount of hydrocarbon surfactant is from 10 to 100% by weight based on the weight of disperse dyestuffs.

12. A dispersion as claimed in any one of claims 1 to 11 wherein the amount of water in the aqueous dispersion is from 25 to 90% by weight of the total weight of the dispersion.

13. A dispersion as claimed in claim 12 wherein the amount of water is from 25 to 50% by weight of the total weight of the dispersion.

14. A dispersion as claimed in any one of claims 1 to 13 wherein the disperse dyestuff is hydrophobic in character.

15. A dispersion as claimed in claim 14 wherein the disperse dyestuff contains an alkyl chain of at least 4 carbon atoms.

16. A dispersion as claimed in any one of claims 1 to 15 wherein the disperse dyestuff, in one of its possible tautomeric forms, is represented by the formula:

wherein A is a phenyl radical which is substituted by a nitro, cyano, trifluoromethyl, -SO2R3, CO -CONK', -COR or -SO2NR4R5 group wherein R3 is an alkyl, cycloalkyl, aryl or aralkyl radical, R4 is hydrogen, alkyl, cycloalkyl, aryl or aralkyl radical, R5 is hydrogen or alkyl, and Z is an unsubstituted or substituted alkyl, cycloalkyl or aryl radical.

17. A dispersion as claimed in claim 16 wherein the radical A is substituted by one or two nitro, cyano, lower alkoxy, hydroxy lower alkoxy, acyloxy, lower alkyl or phenoxy groups.

18. A dispersion as claimed in claim 16 wherein the alkyl radicals represented by R3, R4 and R5 are alkyl radicals containing from 1 to 10 carbon atoms.

19. A dispersion as claimed in claim 16 or claim 17 wherein the cycloalkyl radicals represented by R3 and R4 are cyclohexyl.

20. A dispersion as claimed in claim 16 or claim 17 wherein the aryl radicals represented by R3 and R4 are monocyclic aryl radicals.

21. A dispersion as claimed in claim 16 or claim 17 wherein the aralkyl radicals represented by R3 and R4 are phenyl lower alkyl radicals.

22. A dispersion as claimed in any one of claims 16 to 21 wherein the alkyl radicals represented by Z contain at least 4 carbon atoms.

23. A dispersion as claimed in claim 22 wherein the alkyl radical represented by Z contains from 4 to 12 carbon atoms.

24. A dispersion as claimed in any one of claims 16 and 18 to 23 wherein the phenyl radical A is substituted by a group -SO2NK1R2 wherein Rl is a hydrogen atom or an alkyl, cycloalkyl, aralkyl or aryl radical

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. tated with 333 parts of particulate grinding elements in a mill fitted with discs rotating at 3000 rpm. After 30 minutes a quantity of 20% aqueous glycerol was added to bring the final composition to 40% colour, 16% Reax, 0.27% perfluoro surfactant, 0.31% sodium salt of o-phenylphenol, the remainder being 20% aqueous glycerol. This product was satisfactory for the high temperature dyeing of polyester yarn at 1300C as described in Example 1. WHAT WE CLAIM IS:

1. An aqueous dispersion of a disperse dyestuff wherein the dispersing agent comprises a hydrocarbon surfactant which is a hydrocarbon structure to which a hydrophilic group is attached, and a terminal perfluoro surfactant.

4. A dispersion as claimed in claim 3 wherein the radical R, contains from

5 to 12 carbon atoms.

and R2 is an alkyl radical containing 5 or more carbon atoms.

25. A dispersion as claimed in claim 24 wherein the phenyl radical A is further substituted by nitro, cyano, alkyl, alkoxy, chlorine, bromine, phenyl or phenoxy.

26. A dispersion as claimed in claims 24 or 25 wherein the alkyl radical represented by R2 contains from 5 to 12 carbon atoms.

27. A dispersion as claimed in any one of claims 24 to 26 wherein the aryl radicals represented by R1 are monocyclic aryl radicals.

28. A dispersion as claimed in any one of claims 24 to 27 wherein the alkyl radicals represented by R1 contain from 1 to 12 carbon atoms.

29. A dispersion as claimed in claim 28 wherein the alkyl radicals represented by R are lower alkyl radicals.

30. A dispersion as claimed in any one of claims 24 to 26 wherein R1 is a hydrogen atom.

31. A dispersion as claimed in claim 24 wherein the disperse dyestuff is of the formula:

wherein R1 is hydrogen and R2 and Z have the meanings previously stated.

32. A dispersion as claimed in claim 31 wherein Z represents the n-butyl radical and the SO2NR1R2 group is the sulphon-(2-ethylhexyl)amide group in para position to the azo linkage.

33. A dispersion as claimed in any one of claims 1 to 32 which also contains a watermiscible organic liquid in amount up to 50% by weight based on the aqueous phase, as a humectant and to prevent freezing of the dispersion.

34. A dispersion as claimed in claim 33 wherein the water-miscible organic liquid is a polyhydric alcohol.

35. A dispersion as claimed in claim 34 wherein the polyhydric alcohol is ethylene glycol or glycerol.

36. A dispersion as claimed in any one of claims 1 to 35 which also contains a preservative to protect the dispersion against attack by micro-organisms.

37. A dispersion as claimed in claim 36 wherein the amount of preservative is 0.01 to 0.5% by weight based on the total weight of the dispersion.

38. An aqueous dispersion of a disperse dyestuff as claimed in claim 1 and substantially as hereinbefore described in the foregoing Examples 1 or 2.

39. An aqueous dispersion of a disperse dyestuff as claimed in claim 1 and substantially as hereinbefore described in the foregoing Examples 3 or 4.

40. A method for the manufacture of an aqueous dispersion of a disperse dyestuff claimed in claim 1 which comprises agitating in aqueous medium the disperse dyestuff, terminal perfluoro surfactant, and hydrocarbon surfactant containing a hydrophilic group in the presence of particulate grinding elements and, when a dispersion of sufficient fineness has been produced, removing the particulate grinding elements from the dispersion.

41. A method for the manufacture of an aqueous dispersion of a disperse dyestuff substantially as hereinbefore described in the foregoing Examples 1 or 2.

42. A method for the manufacture of an aqueous dispersion of a disperse dyestuff substantially as hereinbefore described in the foregoing Examples 3 or 4.

43. An aqueous dispersion of a disperse dyestuff whenever obtained by a method as described in claim 40 or claim 41.

44. An aqueous dispersion of a disperse dyestuff whenever obtained by a method as described in claim 42.