dug. 1945 WHITTAKER--''DIAMOND JUBILEE O F DIRECT COTTON DYES" 20 1

The existence of such dye aggregates in wool fibres bee been detected by Astbury and Damonlo from X-ray observations and more recently by Royer and M d * @ from microscopical observation. In the present experi - ments the wool ww so deeply coloured that microscopioal examination revealed nothing. In view of the erne with whch the dyed wool could be disintegrated, it was thought that it might provide a satisfactory subject for examination in the electron microscope and, accordingly, portions of the wool dyed heavily with Carbolan Blue BS were ground in a mortar with a very little dispersing agent and finally diluted with water to form a very fine stable dispersion, the particles of which showed Brownian movement in the microscope. A portion of this suspension waa examined in the electron microscope, but the particles were neither found to possess any recognisable structure, nor could the crystallites of dye, if present, be differentiated from the wool. Support for this view of the tendering process is therefore lacking. It does, however, seem to be the most probable solution and hence this behaviour will probably be associated only with dyes having large molecules. It should perhaps be emphasised that this tendering behaviour ww observed only with very high concentrations of dye on the fibre such as are never attained in practical dyeing; in normal depths of shade no tendering was n beerved.

SUMMlUrY Isotherms for the absorption of three acid dye# of

rlifferent types on wool, silk, casein fibre and nylon have been determined at several pH values. The results may be fitted by the Lamgmuir adsorption equation a t high concentrations, but at low concentrations a depmture froni this equation is observed, from which it is urferred that the dyeing mechanism is more complex than simple mlt formation. At high acidities, hydrolysis of wool occurs during dyeing, leading to increased dye absorption. The degree of hydrolysis is not increased in presence of dye. The amount of a typical colloidal dye absorbed is not in excess of the total number of basic groups present, provided that it is assumed that each amino-group in the

fibre can coiuhno with one dye molecule and not with one dye equivalent.

At very high concentrations of dye in the wool fibre, severe tendering takes place, which 1s attributed to mechanical disruption. due to the formation of large dye crystallites inside the water-swollen fibre, which cannot be aocommodated on drying.

The absorption isotherms of wool and casein fibre ere almost identical. Thew chemical aBnity for dye ia thus the saae, and the observed differences in rate of dyeing and wet fastness must be attributed to differences in physical structure. The dyeing mechanism with nylon app-6 to be similar to that of wool, and, from the quantity of crystalloidal dye absorbed, the fibre appears to oontain 0.06 milliequivalent of baaic groups per g., ag compared with 0.2 milliequivalent per g. for silk and 0.7 milliequivalent per g. for wool and casein fibre. IB~PERIAL CHEMICAL INDUETRIES LTD.

DYBBTWFS DIVISION D ~ H O U S E LABORATORIES

MANOHESTER 9 (Received on let Decembw. 1944)

RE~RBIBCEKI 1 Valkb, Kdtoidchemzache Qvwdhwen tier TeWwedltmg (J. Springer.

2 Freundllch 'and Losev 2. Plrusik. Chem. A 1907 59, 284. 3 Pelet-Jollvet and 9ie' ist Koaoid-Z., I d , 5, h36. 4 Knecht, Be?., 1904, 3 y 3481. 6 Qoodsll this Joerr 1838 55 629. 8 Astbury', tpie Jmr', Ju& ,bolume, 1834, p. 21. 7 Gilbert. Prtuate Comrnunicatzan. 8 Bll)d, Tram. Fnraday Soc., Discussion on Colloidal Electrolyte@,

1936 .306. Tram. Pwudall Sa.. 1833 19 327. 9 Gilbert ah{ RIdAal, Proc. Roy. Sm. A , 1844,'18i, 335. 10 Pfeiffer, Organieche Molekutwrbtndwagen (Stuttgart), 1922. 11 Steinhardt Fugitt and Harris A m Dgedt@ Rep 1842 31. 77. ZZg eakman'aud Hirst, Tram. k'amdav Soc., 1834, 40, 63b. E3 Sreinhardt and Harris. TaztU8 Res.. 1940. 10. 181.

Berlin) 1837

14 Steinhardt slid Harris' ibdd 1840 I0 ZZB., 16 Lloyd and Bidder !l'r&e. S& 1 8 h 31 HH4. 16 Qleysteen and H&ris, A m . Dyestuff Rw., 1941,'30, 26. 17Peter-a this J a r . 1846 61 86. 18 Aatbdy Private kornrnh&trOn. 1SAetbnry'and Damon thin J w r 1938 S4 6. 20 Royer and Mareah, A'&. M/esl& i843. 32, lH1.

The Diamond Jubilee of the Discovery of Direct Cotton Dyee. 18844944 C. M. WHITTAKER

In the fXth number ofthe LJociety's Journal (26th March, 1886, p. 124) is an incomplete abstract of B.P. 4,416 of 1884 covering Paul Bottiger's process for the manu- facture of Congo Red (Colour Index, No. 370), which waa the first member of the direct cotton group of dyes. The patent waa communicated from Lodz, which was at that time in Russia. It would be interesting to know why it was not from Berlin. Where was the Arst laboratory sample of Congo Red made? This makes the Diamond Jubilee of the discoveqy of direct cotton dyes coincide with the Diamond Jubilee of our Bociety. An int'eresting coincidence, because it may be justly said that the direct cotton colours have been used more widely in the textile trade than any other class, and that they have been produced in larger quantities tlim any other class of dyes. Jt is interesting to recall the introduction of the different dyes which marked definite progressive steps in the expan- sion of this group.

Benzopurpurine 4B (Colotdr Index, No. 448) followed closely on the heels of Congo Red, and still remains in continuous use t o this day. It is distinguished by its great mbstantivity for the fibre, which remains unsurpassed. whilst its bright shade was in 1886 -equalled. In the Droylsden laboratory of Courtadds Ltd. it has always been held that if Benzopurpurine 4B can be dyed on any cellulosic package successfully, then any other direct cotton dye can also be successfully dyed. Never was a dyeatd more adulterated in commerce, and prices as low-ae 4d. per lb. prevailed prior to 1914. The next outstanding discovery was that of Primuline

( 0 0 2 ~ Index, No. 812) in 1687 by Green, and the equally valuable disoovery that it could be diazotised and coupled

on the fibre with B-naphthol to produce a red dyeing faet to scouring and acid cross-dyeing, but, unfortunately, not fast to light. Primuline Red became the standard mlour in many types of fabrics and still finds its use for backing thread, although the introduction of Para Red (Colwr I d e z , No. 44) and the azoic dyes has largely diminished its importanoe.

Rosophenine 4B (Colour Index, No. 604) also came out in 1887 and was the first red direct cotton dye of good fagtness to aoids, although it possessed only moderate fastness to light and washing, as well aa poor aftinty for the fibre. Nevertheleas, its fastneqs to acids compelled its use in certain lines, but the dyeing trade had to wait until 1900 for the introduction of Benzo Fast Scarlet 4BS (Golour I&, No. 327), which first oombined faatnew to light and acids with moderate festnese to washing.

In 1889 Diamine Fagt RebF (Golour Index, No. 419) appeared, and its good af&lity and suitability for after- treatment with bichromate or chromium fluoride, together with the fact that it b a m e a standard dye for wool, gave it an extended me. In 1888 Erika B ( C o h r Index, No. 130) v as introduced; it obtained and retained success aa a standard dye for bright pinks, particularly for flannelettes.

Turning to the yellow direct dyes, Chrysophenine G (Colour Index, No. 365) wm discovered in 1886 and, like Benzopiqurine 4B, it was distinguished by great sub. stantivity and, at that time, a high standard of light- fasltnes)s, although its standard of light-fastness hae long since been surpassed by later types of yellow direct dyes. The introduction of Primuline also led t o the discovery

that, by treatment on the fibre with hypoohlorite, a very

WHITTAKER-“DIAMOND JUBILEE OF DIREC‘I’ UOlTON DYES” dug. 1966 ~- __ ____ - ~~ ~~

202

fast yellow shade could be produced possessing good fact- ness to light and washing, although the complete chlorinw tion of Primuline on the fibre still remains one of the moht difficult operations in the dyehouse. Exaniintttion of I I chlorinated Primuline shade on the fibre under ultrw-violet light almost invarably reveals unconverted Primuline. This yellow dyeing has been a standard shade ever since.

In the manufacture of Primuline, dehydrothio-p- toluidine is jointly produced. A t first the latter was regarded as a by-product, whereas the position is now reversed, Primuline being the less desirable of the two. The position was reversed as a result of the discovery- also in 1887-that a very fast-to-light direct cotton yellow- Oxyphenine (Colour Index, No. 814)- could be made by treatment of dehydrothio-p-toluidine eulphonic acid with hypochlorite.

Read Holliday & Sons Ltd., before they learnt sense, sold this product to L. Cassella & Co., no doubt to the immense satisfaction of the latter in being able to buy i t without the Primuline. I,. Cassella & Co. made their Diamine Fast Yellow B by this process and successfully made a type which was superior to all other makes of this product in its behaviour when dyed in a sodium sulphide bath and used in combination with sulphur dyes.

Read Holliday made a series of direct cotton dyes from dehydrothio-p-toluidine, known as “Titan” dyes, but their a f h i t y for the fibre and light-fastness were so poor com- pared with competing types that they belied their name of “Titan” and were a failure.

Chrysamine G (Colour Indm, No. 410) was discovered in 1884, and was largely used a t one time, despite its defects of inferior fastness to alkalis and sensitivity to copper salts.

The marketing of Diamine Fast Oranges EG and ER (C:) and, more recently, the Solar Yellow 2R type (S,), raised the fastness to light of the direct cotton yellom to a very high standard, which still remains unsurpassed by other shades in the direct cotton dye group.

Blue, green and grey direct dyes were so inferior in light-fastness that it was impossible to use them as a drabbing agent without producing an unbalanced fade; fortunately, Durazol Grey VGL (I.C.I.) has remedied that position.

Turning to the blue direct dyes, the Black BH typo (CoEour Index, No. 401), introduced in 1890, provided one of the,most outstanding successes of this group and it is still used in enormous quantities, despite its relative lack of fastness. In the early 1900s i t was t,he subject of some of the most fantaatic price cutting conceivable between the then-competing firms of F. Bayer & Co., Berlin Aniline Go. and L. Cassella & Co., and it was one of the causes of the first movement towards combination amongst the big German fims. I ts suitability for direct or developed navy blue shades made it pre-eminent, whilst its suitability for filling up cotton without staining the wool in mixed fabrics made it one of the brims of Fingle-bath union dyeing, and made modern garment dyeing possible.

Sky Blue FF (Colour Index, No. 518) was introduced in 1891 and became of outstanding importance in the range of blue direct cotton dyes, particularly in view of the fact that its faatness to light is very much improved by after- treatment with copper sulphats. With this dye diould also be included the Blue RW type (Colour Index. No. 512), introduced in 1894 and also very suitable for aftertreat- ment with copper sulphate. Blue direct dyes which are fast to light without aftertreatment with copper sulphate were of much later introduction, and even to-day the fastness to light of the bluef direct cotton dyes still leaves something to be desired in compnrison with Chlorazol Fast Orange AG (I.C.1.). Solar Yellow 2R (S.), Solophenyl Red Brown (Gy.) and Durazol Grey VGL (I.C.I.).

Turning to black direct dyes, Columhia Black FV ( ~ ‘ O h W

Index, No. 539) was introduced in 1898 and Direct Black EW (Colouv Indcz, No. 581) in 1901; they remain the two onManding examples of ordinary direct blacks -in general use and equally were subjects of the same absurd price cutting aa-Black BH.

Diamine Black RMW (C.) was a product to which L. Caasella & Co. gave a great reolame aa a burl-dyeing black. It was frankly a mixture which, i t waa understood, was originated by the agent of L. Camella BE Co. in Vienna, Richard Mdhlau of Wien, hence the brand letters RMW. Countless- hours were spent in the laboratory of Read

Holliday & Sons Ltd. in unsuccessful attempts to match it,. It had one component, an orunge dye, which was neither identified nor substituted sat,isfbctorily by them.

In 1893, Uiaminogen Extra (c‘olour Index, No. 317) and Diaminogon B (C.)- the latter a mixture- occupied an unrivalled and cleverly advertised position in the developed black range; for many years they had a very large a l e for the dyeing of sewing cottons. This supremacy was subsequently challenged by the introduction of Zainbesi Blttcks V and D (A.), which also achieved a large sale, particularly &or the dyeing of sewing cotttons.

The next step forward in black direct cotton dye8 waa the marketing of types suitable for aftertreatment with formaldehyde, e.q. Formal Fast Black (Gy.), which enabled black dyelngs fast to washing to be dyed cheaply, but the majority of them possess the limiting handicap of suffering a diminution in fastness to light by the after- treatment.

The Chlorazol Fast Black BK (I.C.I.) type, particularly for the dyeing of grey shades of superior fastness to light, compared,with those yielded by the ordinary direct blacks, also had a great success until i t was greatly surpassed in fastness to light by the introduction of I)urazol Grey VGL (I.C.I.).

Turning to the green direct dyes, Green B (Colour Index, No. 503) and Green G (Colour I d e x , No. 594) were intro- duced in 1891, the G type being distinguished by being much improved in fastness to milling by aftertreatment with chromium fluoride. Progress in the production of improved direct green dyes &d not proceed in the same manner as with the remainder of the range, and the user had to wait a long time befure the much faster to light and brighter Chlorantine Past Greens BL and 5GLL (S.C.I.) and Diphenyl Fast Blue Green BL (Gy.), were introduced.

This review would not be complete without mentioning the outstanding brown direct dyes, e.g. Brown M (Colour Index , No. 420), introduced in 1887, Brown B (Colour I n d e x , No. 423), introduced in 1894, Diamine Catechines B and G (C.), Pegu Brown (I,.), Chlorazol Drab RH (I.C.I.), and Benzo Fast Browns GL and RL (By.), whilst the introduction of dyes capable of coupling with diazotised p-nitroaniline to give shades of improved fastness t o washing provided a method which was soon adopted by calico printers for discharge styles and still remains in use for that purpose.

In 1929 the present author visited dyestuff manu- facturers to appeal for the production of dyes to cover up uneven dyeing viscose rayon, and fully discufised the methods then current for determining the behaviour of direct cotton dyes on uneven dyeing viscose. The icy reception given to these methods in certain quarters remains an amusing memory in view of the fact that shortly afterwards the same methods were freely discussed in their technical conferences.

The introduction of the Icy1 (I.C.I.) and Benzo Viscose (1.G.) series of dirert dyes was one of the results of this visit and more attention was paid t o giving information on the behaviour of new dyes with uneven dyeing viscose rayon. Fortunately, technical improvements in tho production of continuous filament visrose rayon yarn has considembly reduced the necessity for these special dyes.

All the dycstilff makers followed one another in pro- ducing rtlriges of direct dyes of superior fastness to light, e.g. Sirius Supra (I.G.), Chlorantine Past LL brm& (S.C.I.), Diphenyl Past (Gy.), Solar (S.), Durazol (I.C.I.), etc. Some of these products were new, but many were simply well-known old dyes under a new name, whilst some makers could not resiRt the temptation to include unworthy members in the series, thus, in the present author’s opinion, depreciating the value of the whole aeries.

Dumzol Fast Blue 8GS (I.C.I.) should be mentioned aa the first representative of a new phthalocyanine product, which is distinguished by a very brilliant shade; inci- dentally, the fastness to washing is remarkably improved by an aftertreatment with Fibrofix (Courtaulds Ltd.).

Activity by the manufacturers in the use of the property of copper sulphate to improve the fastness to hght of certain direct dyes was evidenced in the introduction of the Bemio Faat Copper (I.G.) and Coprantine (S.C.I.) series of dyes.

It is a.n unfortunate f m t that copper sdphate tends to make viscose rayon yarn sticky, which is reflected in bad

Aug. lS45 ERRATA. CORRESPONDENCE 208

winding, and elao d t m it non-absorbent, p r t i d m l y of eiee. It is for this reason the,t the prasentLsnthor has alwsys avoided the use of copper sulphate aftertreatment in viscose rayon dyeing.

purpurine 4B, Black BH, Black E, Sky Blue FF, Brown M, and Red F, are still largely used.

Although the direct cotton dyes are the easiest to apply of any clms of dyes, yet, despite this fact, they are correctly

A retrospective survey of this nature reveals the fact that, although the dye-users have frequently been reproved for requiring 80 many specialities, the number of direct dyes used in large quantities wm relatively amall. The users instinctively selected those dyes possessing the greatest substantivity for cellulose. It also reveals the continuous progress made by the dye chemists from the days of Congo Red and Benzopwpurine 4B in producing dyes of excellent fastness to light and improved faatness to waehing. The end of the story is not yet, however, because, although there is a wonderful record of auccess over sixty years, the obvious goal must be the production of direct cotton dyes equal in fastness to the vat dyes.

described as a group of pronounced individualists. It is scarcely flattering, either t o the dye-users or to the

dye-makers, that, in the Diamond Jubilee year of the diecovery of direct cotton dyes, our Society should have a Committee in active session endeavouring to draw up stryldard methods for the classification of direct cotton dyes as regar& compatibility, rate of dyeing and d t sensitivity. Surely, the statement of this fact after sixty years must induce in both dye-makers and dye-users a mood of contemplative humility. Finally, it is also interesting to note that the

manual dealing with the Diamine dyes published by L. Caasella & Co. waa one of the earliest examples of the introduction of dveine literature more lavish and in-

Many auxiliary products have been introduced to improve the fastness to washing of the direot Cotton dyes, hut the ideal and universal product still awaits discovev. Fibrofix r e m a at the moment the most satisfactory product for this purpose, although not in free supply.

It is also interesting to note, despite the competition of faster and better types, that the old dyes, e.g. Benzo-

structive than the partern cards previously distributed. In 1807 it was so valued and 80 novel that Professor J. J. Hummel gave a copy of i t as a prize to the most suocessfnl student of that year in the Dyeing Department of the then Yorkehire &llege--aic tramit qlwia mundi, or to use the l a m @ Of the (Receiverl on lat May, 1945)

“The March Of Time”!

Errata In the paper by D. Trail1 entitled “Synthetic Fibres

from Vegetable Proteins” (this Jour., 1945, 61, 154), two errors occur in Table 111. In the third line below the

heading of column 6, i.e. under “2.5 lb. per sq. in.,” for “34” read “24”; whilst in the fbst column, line 9, for ‘’190%” read “100%”.

CORRESPONDENCE The Editor, Sir,

The Action of Ethylene Sulphide on Wool Barr and Speakman (this Jour., 1944, 60,238) discovered

two sets of conditions under which ethylene sulphide could be used to impart an unshrinkable finish to wool fabrics. In the first method the fabric was soaked in sodium hydroxide solution and then treated with an aqueous-alcoholic solution of ethylene sulphide. They considered that in the alkaline solutions the mercaptam produced by polymerisation of ethylene sulphide caused preferential disulphide cross-linkage breakdown in thg aurface scale etructiue of the wool fibres.. In the second method the wool was exposed to the vapours of ethylene Rulphide and wnter at 50% when the ethylene ~ulphide polymerised within the fibre. Experiments we have made provide evidence that in this latter case also the ethylene sulphide reacts with the disulphide woRn-linkages of the wool.

A tubular fabrir knitted from a 2/36s, 14 x 9 t.p. in. ywn spun from a 64s quality top was scoured in a solution of potassium oleate and sodium sesqnicarbonate. Patterns of fabric each weighing 2 g. approx. were treated with ethylene sulphide and water vapour, n8 described by Rarr and Speakman, and removed after varying intervals of time. After standing in water overnight, the patterns were rinsed in running water, dried and conditioned at 21%. and 70% R.H., and then weighed and analysed. The thiol- and disulphide-sulphur contentti of the wools were determined by Shinohara’s modification (J. Riol. Chem., 193.5, 109. 666: 1936. 112. 671) of Folin nnd Marenzi’s method ( 2 i ; d . . 1929, 83, 103), colorimetric com- parisons heing made in a Spekker abuorptiometer. Hydro- lysis was carried out for 4 hr. with B~-hydroch~oric acid. the insoluble residue of polymeric ethylene sulphide being filtered off before analysis. Increasing the time of hydrolysis to 24 hr. did not alter the values obtained for the disnlphide.sulphm. The analyses given in Table I show that the diaulphide-

sulphur of the wool decreases as the time of treatment with ethyleno sulphide increases. The treated wool con- tains no appreciable a w u n t of thiol-sulphur.

TARLE I ANALYEEE O I WOOLS M E B TBEA’TKBNT WITE ETHYLENA SULPBIDL

AND WATER V4WUB AT 50%. (a) TREATXENT OF O R I Q ~ A L WOOL

I

Time of Treatment 1 Incrcasn In Disulphlde-

Ethylene Subhide 1 with Weight. . sulphur. Thlol-

sulphur*

0 2 4 A

10 n

8.08

1.58 1.13 0.63 0.77 0.72

1.28 0.03 0.04 0.03 0.01 0.1 I\ 0.01 0.02

(b) TBBATXENT OF TarOLACETIC A r m - I i E n o c E D WOOL

n I - I n m - -- 2 25.1 1.02

4 1 06.8 I 0.14 A 784 0.15 8 71.3 0.18 10 I 90.7 1 0.14 10.5 76.3 0.12

2.15 0.14 0.06 0.04 0.04 0.02 001

0 2 4 6. 8

10 ~ 10.6

- 17.4 20 8 26.2 254 24.2 274

1.95 0.19 0.18 0.11

0.16 0.1 e 0.1 n

- ~- C’ahilatrd on the dry weight of the uiitlrated wool. In order to

make thla rnlrulation the percentnge rcdiirtioii 11) regain of the wool ciiuwd by ethylene shphlde trentnlrnt WNR estimated from the data ot Rarr and Spenkmsn (Fig. 8 )

It is possible to reduce some of the disulphide groups of wool to thiol groups by m e m of bhiolaoetic wid (Patterson, Geiier, M i d l and Harris, Bur. Stand. J . Ree., 1941, 27, 89). Patterns of wool, which had been reduoed with twenty times their weight of tl M-solution of thiol- acetic acid a t pH 4-2 and 4 0 ” ~ . for 24 hr., were treated with ethylene sulphide, when the thiol- and disulphide-sulphur