US1886947A - Dye and dyeing - Google Patents

Description

Patented Nov. 8, 1932 UNITED STATES PATENT orr cs DAVID ALEXANDER WHYTE FAIRWEATHER, OF GRANGEMO'UTH, ANIJ.JOHN THOMAS,

013 KING-ARTE, POLMONT, SCOTLAND, ASSIGNORS TO IMPERIAL CHEMICAL INDUS- TRIES LTD., A CORPORATION OF GREAT BRITAIN DYE AND DYEING No Drawing. Application filed December 9, I930, SerialNo. 501,130, and in Great Britain December 9, 1929.

It is an object of theinvention to provide improved or modified processes for the development of such esters.

We have observed that the development of estersof this type appears to be in part a reversible reaction, and our invention consists in a suitable adjustment of this reversible reaction so as to facilitate the development of the colour or to prevent over oxidation. We achieve this result, for example,

in the case of development with ferric salts by the addition of a little ferrous salt or by the addition of salts of weak acids capable of forming double salts with the ferric salt present. In the case of development with copper salts, in which it is probable that the copper salt is converted into cuprous salt, acid and oxygen (the oxygen being utilized in developing the ester), we achieve this same result by reducing the concentration of acid originally present.

In developing dyeings of the esters of reduced vat dyestuffs using ferric sulphate we have found that the addition of ferrous sulphate is of great advantage, for instance, uslng ferric sulpiiate alone it is very easy to obtain oVer-oxi tion, particularly with certain dyestuffs, for example, those belonging to the indanthrone'class.

By the use of ferrous sulphate it is possible to easily avoid any over-oxidation. This result is very unexpected, since the addition of a reducing agent would not be expected to have any effect on the developing process.

One special advantage of this addition of ferrous sulphate is that it is possible to regulate the strength of the oxidizing agent with precision to suit any particular dyestufi by varying the relative proportions of ferric and ferrous sulphate. The oxidation is preferably carried out in the presence of acid.

Instead of using ferric sulphate and ferrous sulphate, ferric chloride and ferrous chloride or other pairs of ferric and ferrous salts may be used. 7

It is possible that the beneficial effect of the ferrous salt is due to the fact that the reduction of a ferric to a ferrous salt is a reversible reaction.

Instead of using pairs'of salts with the same acid, such as ferric sulphate and ferrous su'lphate it is possible to use ferric and ferrous salts of different acids for instance, ferric chloride and ferrous sulphate. Using ferric sulphate and ferrous sulphate and acidulating, sulphuric acid forms a convenient acid. With ferric'chloride and ferrous sulphate, hydrochloric acid forms a convenient acid. Salt may be added in addition.

It is possible to omit addition of a ferric salt altogether, and form it in situ, it being practicable, for example, to work with ferrous sulphate and sulphuric acid in the presence of air, but for large-scale operations development under these circumstances may not be sufliciently fast.

Another method of developing a ferric salt is to use a ferrous salt in conj unetion with an oxidizing agent, for example, a nitrite or persulphate and in these cases a small quantity of the additional oxidizing agent will sometimes be found sufli'cient.

It is known to develop esters of reduced vat dyestuffs and similar substances by the use of copper salts in acid solutions.

One of the great advantages of the use of copper salts in this connection is the wide range of applicability of the copper salts and the fact that it is easy to carry out the oxidation without over-development.

The use of acid is common to nearly all methods of developing esters of reduced vat dyestuffs but we have discovered that reducing'the concentration of acid in developing with copper salts increases instead of reduces the developing power; thus, a solution of cupric chloride is a stronger developing agent than a solution of cupric chloride containing hydrochloric acid. The actual strength of the developing agent can therefore bevaried and controlled by altering the strength of the acid. I

This phenomenal-result has the advantages that it is possible to eliminate or to reduce the concentration of the acid and also that development can be made to take place more rapidly. In carrying out this part of the invcntion cupric chloride may be used, or alternatively copper sulphate'with the addition of sodium chloride.

The explanation of the phenomenon is probably to be found in the fact that the reduction of cupric salts, to give cuprous salts, acid, and oxygen, is a reversible reaction.

When using ferric salts as developing agents for the ester salts of reduced vat-dyestufi's the addition of salts of weak acids which will form double salts with the ferric salt presents certain advantages.

As is known in using ferric salts, particularly with some dyestufi's which are easily over-oxidized, over-development is liable to take place.

The foregoing method however is of special use in avoiding over-oxidation, whilst the use of double salts obtained from ferric salts and salts of strong acids is not of the same advantage, since with these the liability to overoxidation still exists.

The present invention, therefore, includes theuse of double salts in the manner which is mentioned, preferably in the presence of a small quantity of acid.

The invention is further illustrated by the following examples in which the parts are parts by weight.

Example 1 curs even if the development is carried on for over 10 minutes, and a pure bright blue shade results.

Example 2 In place of the ferricsulphate used in Example 1 in a bath otherwise of the same composition, an equivalent quantity of an oxidizing agent such as per-sulphate, bichromate, &c., may be added, these probably oxidiz ing part of the ferrous sulphate to the ferric state and so producing a bath pfv the same ,"oxidizing power as in Example 1;

Example 3 dyed with 4 per cent times its weight of the sulphuric ester salt of leuco indigo is developed in the following bath:-

Example4 7 Cotton cloth is padded with a 2 per cent solution of the tetra-sulphuric ester of leuco indanthrone and dried.

The yellow dyeing so obtained is developed in the bath specified in Example 3 for 10 minutes at 80 C. Blue dyeings of exceptional brightness are thus produced, and the time of development and temperature may be varied within wide limits without superoxidation to the yellow azine occurring.

' If necessary 10 percent of sodium chloride or sulphate may be added to the developing bath to prevent bleeding of the colour.

Example5 Cottoncloth padded witha 2 per cent solution of the tetra-sulphuric ester salt of leuco indanthrone is developed in bath containing 2 per cent hydrated ferrous sulphate, per cent hydrated ferric sulphate may be considerably varied.

Examplefi In place of ferric sulphate in Examples and 5 an equivalent quantity of ferric chloride may be used.

Example 7' I and per cent sulphuric acid for 20 min- I 'utes at 50C. The time and temperature Cotton cloth is dyed with the ester salt of leuco Bb2 :'Bz2 dimethoxydibenzanthrone' (caledon jade green) and the orange brown dyeing is immersed either in the bath specified in Example 3 or that of Example 5 in the cold for a few minutes.

Example 8 W001 dyed as in Example 1 is developed in a bath containing 40 parts of' a 10 per cent solution of ferric chloride, 360 parts of a 2 per cent solution of ammonium oxalate crystals, 55 parts of concentrated hydrochloric acid, and 160 parts of water, for 4 .minutes at 90 C.

' Exam plc 9 Cotton cloth padded as in Example 4 is immersed at 90 C. in a 2 per cent solution of crystalline cupric sulphate in water. Developmentproceeds rap dly and the dyeing may be lifted and rinsed in about 5 minutes.

Example 10,

Wool dyed as in Example 1, is developed in an aqueous bath containing 2 per cent ferric ammonium citrate and 0.2 per cent sulphuric acid, for 30. minutes at 90 C.

Example 11 i The proportions of the constituents of a developer containing ferrous sulphate may be considerably varied without appreciably altering the shade produced in the case of a dyeing with an indanthrene ester. A smaller quantity ;of ferrous sulphate than in the previous examples is satisfactory when the fabric is of wool, employing the following bath containing 2 parts hydrated ferric sulphate, 5 parts hydrated ferrous sulphate and 5. parts sulphuric acid'in 1000 parts of water. Development may be carried on at 85 C. for 15-30 minutes.

Example 13 In place of ferrous sulphate in any of the previous examples, ferrous ammonium sulphate in proportionately larger quantity may be employed. The development is somewhat retarded and a slightly longer time in the bath is usually necessary for the production of the correct shade.

V General The invention is not limited to sulphuric esters. V Y

The invention includes development of the dyestuflf in substance. It includes colouring generally, for instance, dyeing as well as printing and padding.

. As many apparently widely different embodiments of thisinvention may be made without departing from the spirit and scope thereof, it is to be understood that we do not limit ourselves to the specific embodiments thereof except as defined in-the appendedpatent claims.

We claim:

1. Process for the development of enolic leuco-ester salts of dyestuffs in the presence of a ferric salt characterized by the addition of an agent capable of influencing the reversible reaction which the ferric salt under I goes during the development, said agent being a salt of'the class consisting of ferrous salts and salts of weak acids capable of forming double salts with said ferric salts.

3. Process according to claim 1 in which i the added agent is a salt of a weak acid which salt is capable of forming a double salt with I the ferric salt.

4. Process according to claim 1 in which the development occurs inthe presence of ferric sulphate and the added agent is fer.- rous sulphate: p

5. Process according to claim 1 in which the added'agent is an ammonium salt of a weak acid. 6. Process according to claim 1 in which the added agent is ammonium oxalate.

7. Process according to claim 1 in which there is present, in addition to the ferric salt, another developing agent.

8.Process according to claim 1 in which there is present, in addition to the ferric salt, a sibstance capable of generating nitrous aci 9. Process according to claim 1 in which the ferric salt is generated in situ by oxidation of a ferrous salt.

10. Process according to claim 1 in which part of the ferric salt is generated in situ by oxidation of a ferrous salt.

11. Process according to claim lin which, in addition to a ferric salt as developer and a ferrous salt as agent for influencing the reversible reaction, there-is also present another oxidizing agent.

12. Process according to claim 1 in which a small quantity of acid is also present.

13. Process for the development of enolic leuco-ester salts of dyestufls in the presence of ferric sulphate, ferrous sulphate, and sulphuric acid.

14. Process of a ferric salt, characterized by the employment of the ferric salt in the form of a double ferric salt of a weak acid.

.15. Process according to claim 14 in which the double ferric salt used is a ferric ammonium salt of an organic carboxylic acid.

16. Process according to claim 14 in which a small quantity of acid is also present.

17. A process of developing enolic leucoester salts of dyestuffs which comprises immersing a fabric impregnated with said ester salts, in a developing bath comprising an oxidizing agent and a ferrous salt and efiecting the development of said dyestuffs.

18. The process of claim ,17 in which said oxidizing agent is a ferricsalt.

In testimony'whcreof we aflix our signatures.

. DAVID ALEXANDER WHYTEFAIRWEATHER.

JOHN THOMAS.

for the development of enolic 'leuco-ester salts of dyestuffs in the presence 2. Process according to claim 1 in which the added agent is a ferrous salt.

CERTIFICATE OF CORRECTION.

Patent No. l, 886, 947. I s I November 8,1932.

DAVID ALEXANDER WHYTE FAIRWEATHER T -It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 95, after "in" insert the words "an aqueous"; andline 109, for the syllable "BbZ" read "B22"; and that the said Letters7Patent should be read with these corrections therein that the same may conform to the record of the case in. the Patent Office.

Signed and sealed this 27th day of DecemberA. D. 1932.

' J. Moore, (Seal) Acting Commissioner of Patents.