GB2263912A

GB2263912A - Dyestuff compositions

Info

Publication number: GB2263912A
Application number: GB9202656A
Authority: GB
Inventors: Barry Mclow
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1992-02-07
Filing date: 1992-02-07
Publication date: 1993-08-11
Also published as: GB9202656D0

Abstract

A dyestuff composition comprises (A) one or more direct dyes, the dye or mixture of dyes having a light absorption maximum wavelength lambda max of 390 nm to 510 nm and (B) a fluorescent whitening agent. (A) may be an azo dye or a stilbene dye and (B) may be a stilbene such as a 4,4' - bis (triazin-2-ylamino) stilbene - 2,2' - disulphonic acid or a salt thereof. The compositions may be used for dyeing viscose.

Description

Compositions This invention relates to dyestuff compositions suitable for use in the dyeing of cellulosic film, particularly viscose (regenerated cellulose) film and to the use of the compositions in the production of coloured cellulosic film.

Coloured viscose film, for use in packaging and other applications, has conventionally been produced by passing newly formed colourless viscose film, while still wet and before treatment with softener (plasticizer), through an aqueous solution or dispersion of a direct dye. Certain coloured viscose film, for example film to be subjected to lithographic printing processes, is required to exhibit significant absorption of UV light. Conventional attempts to provide such absorption properties, by increasing the amount of dye used in the dyeing process, often give film which is dark and lacking in clarity and yet still has inadequate absorption properties. Furthermore, the use of increased amounts of dye makes the production of the coloured film uneconomical.

It has now been found that coloured viscose film which is clear and has good UV absorption characteristics can be produced by dyeing viscose film using a mixture of a direct dye having a light absorption maximum wavelength Xmax from 390nm to 5lOnm and a fluorescent whitening agent.

Accordingly, the present invention provides in one aspect a dyestuff composition comprising (A) one or more direct dyes, the dye or mixture of dyes having a light absorption maximum wavelength Xmax of 390 nm to 510 nm and (B) a fluorescent whitening agent.

Direct dyes having a suitable Xmax value include many of those previously used for the dyeing of cotton, paper and regenerated cellulose, for example thiazoles, phthalocyanines, oxazines, azo dyes and stilbene dyes. Preferred direct dyes (A) are stilbene dyes and, especially, azo dyes.

Examples of suitable stilbene dyes are C.I. Direct Yellow 6, C.I. Direct Yellow 11, C.I.

Direct Yellow 19, C.I. Direct Orange 15, C.I. Direct Orange 34, C.I. Direct Orange 37, C.I.

Direct Orange 39, C.I. Direct Orange 41, C.I. Direct Orange 61, C.I. Direct Orange 70, C.L Direct Orange 71, and mixtures of two or more thereof. These dyes are either available commercially or may be prepared by known procedures.

Examples of suitable azo dyes are C.I. Direct Yellow 4, C.I. Direct Yellow 12, C.I. Direct Yellow 27, C.I. Direct Yellow 44, C.I. Direct Yellow 50, C.I. Direct Yellow 72, C.L Direct Yellow 84, C.I. Direct Yellow 137, C. I. Direct Yellow 157, C.I. Direct Orange 8, C.

I. Direct Orange 26, C. T. Direct Orange 29, C.I. Direct Orange 72, C.I. Direct Orange 73, C. I. Direct Orange 102, C.I. Direct Red 239, C.I. Direct Red 262, and mixtures of two or more thereof. These dyes are either commercially available or may be prepared by known procedures.

Mixtures of one or more azo direct dyes such as those hereinbefore described with one or more stilbene direct dyes such as those hereinbefore described may be used as component (A) of the compositions of the invention, if desired.

Preferred direct dyes (A) are those having Xmax from 400 nm to 500 nm, more preferably from 410 nm to 490 nm, especially from 420 nm to 450 nm. Anionic direct dyes are preferred as also are liquid direct dyes, which are often liquid formulations of solid dyes admixed with solvent, usually water. A specific especially preferred direct dye is C.L Direct Yellow 137.

The fluorescent whitening agent (B) may be, for example, a fluorescent whitening agent, alternatively known as a fluorescent brightener, an optical brightener or an optical whitening agent, known for the treatment of cellulosic textiles or paper. Such fluorescent whitening agents include stilbenes, such as mono(azol-2-yl) stilbenes, for example sulphonic acid group-containing 2-(stilben-4-yl)naphthotriazoles and their alkali metal and amine salts, bis(azol-2-yl) stilbenes, for example 4,4'-bis(triazol-2-yl)stilbene-2,2'-disulphonic acids and their alkali metal and amine salts, and bis(triazinylamino)stilbene sulphonic acids, for example 4,4'-bis(triazin-2-ylamino)stilbene-2,2'-disulphonic acids, including those of formula

where R1 is phenylamino, m-sulphophenylamino, p-sulphophenylamino or 2,5-disulphophenylamino and R2 is methylamino, diethylamino, N-methyl-N-2-hydroxyethylamino, bis (2-hydroxyethyl)amino, morpholino, phenylamino or methoxy, and alkali metal and amine salts thereof.

Other fluorescent whitening agents used in the treatment of cellulosic textiles and paper include styrylbenzenes, for example 1,4-bis(styryl)benzenes and 4,41-bis(styryl)biphenyls such as 4,41-bis(o-sulphostyryl)biphenyl.

Preferred fluorescent whitening agents are stilbenes, especially 4,41-bis(triazin-2-ylamino)stilbene-2,2'-disulphonic acids, or alkali metal salts or amine salts thereof, particularly a compound of formula I where Rl is m-sulphophenylamino and R2 is bis(2-hydroxyethyl)amino (C.I. Fluorescent Brightener 336).

In especially preferred compositions of the invention, the direct dye (A) is C.I. Direct Yellow 137 and the fluorescent whitening agent (B) is C.I. Fluorescent Brightener 336.

In the compositions of the invention, the weight ratio of direct dye (A) to fluorescent whitening agent (B) may be from 3:1 to 1:3, preferably from 2:1 to 1:2 and especially from 1.5:1 to 1:1.5. The composition may be supplied to a cellulose film manufacturer as a mixture of (A) and (B) in water, the amount of water being, for example, up to 50% by weight of the composition, conveniently from 5 to 20% by weight of the composition. In use, the composition is diluted with water to give an aqueous composition containing, for example, from 0.2g to 100g, preferably 30 to 80g, of the mixture of (A) and (B) per litre of diluted composition.

The present invention provides, in another aspect, a method of dyeing a viscose film which comprises treating the film with a dyestuff composition of the invention as hereinbefore described. Usually, the viscose film is passed through one or more baths of an aqueous composition containing a mixture of the direct dye (A) and the fluorescent whitening agent (B) in an amount of 0.2g to 100g, preferably 30 to 80g, per litre.

Conveniently, the viscose film is dyed during its production, before the conventional stage of treatment with a softener for the film.

In a typical procedure, viscose is extruded through a narrow slot into a coagulating regenerating bath of sulphuric acid and sodium sulphate dissolved in water. The resulting film is washed to remove acids and salts, desulphurized, washed again and bleached if desired. After washing in a cold water bath, the film is passed through one or more baths containing a dyestuff composition of the invention in diluted form as hereinbefore described. The dyed film is washed with cold water, passed through a softening bath where it is treated with plasticizer, dried and wound onto rolls.

The invention is illustrated by the following Example.

Example A viscose film, which has been extruded, coagulated, desulphurized and washed by conventional procedures, is passed on driven rollers successively through two dyeing baths. The dyeing baths each contain an aqueous composition consisting of a mixture of equal parts of C.I. Direct Yellow 137 and Fluorescent Brightener 336 dissolved in water at a concentration of 60g per litre. The dyed film is washed, passed through a softening bath where plasticizer is applied in a conventional manner, dried and wound onto a roll for subsequent use. The coloured viscose film thereby obtained has the good UV absorption properties required of a film to be subjected to a lithographic printing process.

Claims

1. A dyestuff composition comprising (A) one or more direct dyes, the dye or mixture of dyes having a light absorption maximum wavelength Xmax of 390 nm to 510 nm and (B) a fluorescent whitening agent.

2. A composition according to claim 1, in which (A) is an azo dye or stilbene dye.

3. A composition according to claim 1 or 2, in which (A) has Xmax of 410 to 490 nm.

4. A composition according to claim 3, in which (A) has Xmax of 420 to 450 nm.

5. A composition according to any of the preceding claims, in which (A) is an anionic dye.

6. A composition according to any of the preceding claims, in which (A) is a liquid dye.

7. A composition according to any of the preceding claims in which (A) is C.I. Direct Yellow 137.

8. A composition according to any of the preceding claims in which the fluorescent whitening agent (B) is a stilbene.

9. A composition according to claim 8, in which (B) is a 4,41-bis(triazin-2-ylamino)stilbene-2,2l-disulphonic acid or an alkali metal or amine salt thereof.

10. A composition according to claim 9, in which (B) is of formula

where R1 is m-sulphophenylamino and R2 is bis(2-hydroxyethyl)amino.

11. A composition according to any of the preceding claims, in which the weight ratio of the direct dye (A) to the fluorescent whitening agent (B) is from 3:1 to 1:3.

12. A composition according to claim 11, in which the weight ratio of (A) to (B) is from 2:1 to 1:2.

13. A composition according to claim 12, in which the weight ratio of (A) to (B) is from

1.5:1 to 1:1.5.

14. A composition according to any of the preceding claims which also contains water.

15. A composition according to claim 14, which contains up to 50% by weight of water.

16. A composition according to claim 14, containing 0.2g to 100g of the mixture of (A) and (B) per litre of composition.

17. A method of dyeing a viscose film which comprises treating the film with a composition according to any of the preceding claims.

18. A method according to claim 17, in which the film is passed through one or more baths of a composition according to claim 16.

19. A method according to claim 17 or 18, in which the film is dyed before treatment with a softener therefor.

20. A composition according to claim 1, substantially as described in the Example.

21. A method according to claim 17, substantially as described in the Example.