IDENTIFICATION OF REACTIVE DYES ON CELLULOSIC FIBRES-Ill 117

Conclusions Interesting modifications in textile properties have been pro-

duced on a laboratory scale by depositing thin polymeric surface coatings on to fabrics. They include improved antisoil and soil- release properties of Terylene and nylon 6.6, improved water repellency of Terylene and cotton, and improved dyeability of Terylene with basic dyes, although only surface dyeing is achieved. The resistance to soiling of Terylene fabric is very markedly improved merely by activating the surface of the fabric by an argon glow discharge. Glow-discharge techniques provide a novel method of modifying surface properties without markedly altering the bulk properties of textiles. The textile industry should be aware of new techniques that, with advancing tech- nologies, may be used in on-line treatment of textiles.

A recent paper by Bradley and Fales (22) complements some of the work described in this paper.

* * * We thank Mr N. Wilson, and Mr S. C. Simmens and Miss G.

Hadfield (Shirley Institute) for resistivity measurements and microscope examination, respectively, and Mr D. Keyworth and Mr D. Robins (Shirley Institute) for experimental assistance. (MS. received 9 August 1971)

References I Goodman, J. Polymer Sci., 44 (1960) 551. 2 Bradley, Ind. Engng Chem., Prod. Res. Dev., 9 (1970) 101. 3 Brick and Knox, Modern Packaging, (1965) 123. 4 Mearns, Thin Solid Films, 3 (1969) 201. 5 Williams, J. Oil Col. Chem. Assocn, 48 (1965) 936. 6 Coleman, BP 1,184,451 (1967). 7 Sauter, German P 1,066,013 (1959). 8 Reinsch, Kunstst.-Plast., 11 (1964) 213. 9 Schonhorn and Hansen, J. Appl. Polymer Sci., 11 (1967) 1461. 10 Hall, Westerdahl, Devine and Bodnar, ibid., 13 (1969) 2085. 11 Goring, Pulp Paper Mag. Canada, 68 (1967) T372. I2 Goring and Suranyi, ibid., 70 (1969) T390. 13 Kassenbeck, French P 1,256,046 (1961). 14 Thorsen and Kodani, Text. Research J., 36 (1966) 651, and refer-

ences cited therein. 15 Brown, unpublished work. 16 Wilson (Shirley Institute), to be published. 17 Denaro, Owens and Crawshaw, Europ. Polymer J., 6 (1970) 487. 18 Davidson, J. Textile Znst., 39 (1948) T65. 19 Byrne and Arthur, Text. Research .I., 41 (1971) 271. 20 Bolland and Cooper, Proc. Roy. Soc., A225 (1954) 405. 21 Sagar, J.C.S., B, (1967) 1047. 22 Bradley and Fales, Chem. Tech., (1971) 232.

Publications Sponsored by the Society's Identification of Dyes Committee-lX

Identification of Newer Types of Reactive Dyes on Cellulosic Fibres-I11 F. JORDINSON AND R. LOCKWOOD

Dyeing and Finishing Section, Department of Textile Industries, Huddersjield Polytechnic, Huddersfeld H D I 3 D H

Tine reactive systems and chromogens present in further types of reactive dyes are briefly discussed. Dyeings or prints on cotton of selected dyes in each range, including more black reactive dyes, have been tested to distinguish between the various types of reactive

dyes. Tests for detecting the presence of metals in reactive dyeings are included.

Introduction The first decade after the introduction of reactive dyes in 1956

was characterised by developments that rapidly extended the number of reactive systems and chromogens. It is not surprising, however, that with reactive dyes for cellulosic fibres this spect- acular development has decelerated. Advances in the chemistry of reactive dyes are now mainly achieved by careful manipulation of chemical and physical properties to give dyes for particular technical applications. Thus, the newer types of dyes tested since the publication of part I1 ( I ) posed no special problems of identification. The only additional studies carried out were a more detailed investigation of the Thumm and Benz tests (2) and a careful examination of methods of detecting the presence of metals, since several reactive dyes are metal complexes. Most of the dyeings tested were approximately 1/1 depth, except for the blacks, which were approximately 2/1.

The Thumm and Benz test, using cold alkaline sodium dithion- ite, is a very reliable confirmatory test for phthalocyanine reactive dyeings. It is effective even with metallised phthalo- cyanines, with which the Hoechst confirmatory test (spotting with concentrated nitric acid, followed by cold acid stannous chloride) fails. Accordingly, attention was directed to extending the Thumm and Benz test for characterising anthraquinone reactive dyeings. Our results were generally in line with those obtained for different dyes by Thurnm and Benz, after the treatment (30 s) with cold alkaline dithionite. It should be stressed, however, that the reagent must be freshly prepared

before use, for, even if the alkaline dithionite is used only a few hours after preparation, with many dyeings the colour changes in the blank vat and the effects of rinsing are different from those reported.

Detailed information on modern procedures for the detection of metals present in dyed textiles is given in Clayton's Tables (3), by Thumm and Benz (4) and by Burdett (5). As the amounts of metal present in any reactive dyeing on a cellulosic fibre are extremely small, detection is by no means easy. However, after extensive trials using the above three methods, we decided to follow the general procedure recommended by Burdett (5). Owing to difficulties encountered in heating micro-crucibles, small standard porcelain crucibles (40 cm) were used and were found suitable for ignitions. This necessitated using 0.15-0.20 g of material for each test, the sample being cut into very small pieces, then gently ignited, after which the crucible lid was attached and the crucible heated strongly for several minutes. After adequate cooling, a few drops of a hot saturated solution of sodium nitrate were added and the mixture was heated strongly until a clear melt was obtained. After cooling, the residue was extracted with a little warm distilled water and the extract filtered, the filtrate being tested for chromium.

Test for Chromium-A yellow filtrate strongly suggests the presence of chromate. Acidify the solution with a few drops of glacial acetic acid and add a few drops of s-diphenylcarbazide (0.25% s o h in ethanol). The solution turns reddish violet if chromate is present.

118 JSDC MARCH 1972; JORDINSON AND LOCKWOOD

TESTS FOR OTHER METALS

Metals other than chromium will remain in the residue on the filter paper and in the residue in the crucible. These residues are dissolved in a small amount of dilute hydrochloric acid and combined. The solution is made alkaline by adding ammonium hydroxide (conc.), and separate portions of the solution are then tested for metals as follows:

Copper-To a few ml of the test solution add an equal volume of sodium diethyldithiocarbamate (0.1 % aq. soln). A golden brown coloration or precipitate indicates the presence of copper.

Cobalt-To a few ml of the test solution add a few drops of 1-nitroso-2-naphthol (soh of 0.1 g in 5 ml glacial acetic acid diluted to 10 ml with distilled water). If cobalt is present, a brown precipitate develops.

Nickel-Add a few drops of Nioxime (0.8% aq. soln) to a portion of the test solution. A red coloration or precipitate indicates the presence of nickel.

Freshly prepared solutions of Analar reagents were used throughout and after each test the colorations or precipitates were checked against blank tests using distilled water, Of the above four metals, chromium and copper are present in many more reactive dyes than cobalt and nickel. In fact, in all the reactive dyeings found in the present work to contain a metal, this was either chromium or copper (see Table 10).

Six more ranges of reactive dyes have been examined, using dyeings or prints on cotton. The dyes were selected so as to cover various chromogens. The general procedure followed has been described earlier (2). Additional tests for metals were carried out on those dyes thought to be complexes. No new Remazol (FH) dyes were tested, as we were informed (6) that the new d e velopments in these dyes do not affect their reaction with the fibre via vinyl sulphone linkages and, therefore, will not present new problems in their identification.

Procion Supra Dyes * (Continuation) These dyes are probably monochlorotriazinyl dyes (7). A

second reactive system is incorporated to obtain almost 100% fixation in printing. By building special features into the molecule the planarity is disrupted, which minimises hydrogen bonding between unfixed dye and the cellulose, so that any traces of hydrolysed dye are easily removed in washing-off.

Levafix P Dyes (Continuation) According to the AATCC ( 1 ) the reactive system in these dyes

is a methylsulphonyl heterocyclic grouping. Beech (8) states that * These dyes are now named Procion SP dyes

Test Boil for 2 min in 5% NaOH

(Clayton) Hoechst solvents test Acid cross-dyeing test (Bode) Formosul G (Clayton)

Acid stannous chloride (FH)

they are alkylsulphonylpyrimidino dyes derived from products such as 4,5-dichloro-6-methyI-2-methylsulphonylpyrimidine (:I) :

I DNH

Levafix P dye

MecysoaMe c1 \,N

Rernahol H Dyes (9) Whereas the earlier Remazol dyes are essentially sulphatoethyl-

sulphonyl dyes [DSO,CH,CH,OSO,Na], the Remazol H dyes contain a dialkylaminoethylsulphonyl group [DSO,CH,CH,N *

(Alk)2]. In both cases the dye reacts with the cellulosic fibre by means of a vinyl sulphone (DSO,CH,:CH,) system formed in the presence of alkali. Thus the same linkage is obtained with both ranges via the same intermediate stage, although the two ranges differ greatly in their rate of reaction.

Cibacron Pront Dyes These dyes were introduced in 1968 for the printing of cotton

and regenerated-cellulose materials. They are mentioned in the Colour Index (10), but no definite information is available about their chemical composition, except for the chromogens. They contain a highly reactive system, probably monochlorotriazinyl (7) like the earlier Cibacron dyes. Stead also states that, in Cibacron Pront dyes, the non-labile group is specifically chosen to promote a high degree of reactivity and therefore to accelerate fixation in both 'all-in' and two-stage printing processes.

Prints on cotton of four Cibacron Pront dyes were tested in the usual way and the results are given in Table 1.

Like Cibacron dyeings, the four Cibacron Pront prints were greatly affected by acid cross-dyeing. In boiling dilute sodium hydroxide they became paler, owing to bleeding, whereas Cibacron dyeings were resistant. Attention is drawn to the behaviour of Cibacron Pront Scarlet 3R (C.I. Reactive Red 13) on reduction, and re-oxidation with persulphate. The colourless pattern turned orange-brown, as did some other red reactive dyes (I, 2).

Reactdil Dyes In 1968 Geigy introduced the Reactofil dyes for use on

cellulosic fibres. The chromogens of many of these dyes are disclosed (lo), but the reactive system is not.

Of the six dyeings on cotton chosen for testing, three are of straightforward monoazo dyes, i.e. the yellow and the two reds. One of the three blue dyeings is of a phthatocyanine dye (C.1.

TABLE 1 Behaviour of Cibacron Pront Dyest

Yellow 4R Scarlet 3R Blue 3R Turquoise G (C.I. Reactive Yellow 56)

(Monoazo) (Monoazo) (An thraqumone) (Phthalocyanine) Slight LC (GS 4) LC (GS 3-4B) LC (GS 3) LC (GS 3) 4 No staining of white cotton --•

Slight LC GS 4) Very slight LC (GS 4-5)

Navy blue, Faint greenish Permanently decolorised Decolorised, Orange- Yellow, Purple with

(C.I. Reactive Red 13) (C.I. Reactive Blue 74) (C.I. Reactive Blue 75)

No LC

brown with persulphate persulphate blue with persulphate

Very slight LC GS 4-5) LC (GS 2- s C) SW (GS 2) LC (GS 3) SW (GS 2) LC (GS 3) SW [GS 2) LC (GS 2-3) SW (GS 3)

As above

Alkaline dithionite (Thumm and Benz)

Conc. HNO, and acid stannous chloride (FH) tGS -Grey Scale LC =Loss of colour SW =Staining of wool

Decolorised As above Pale orange with persulphate

As above

Purplish brown Bluer on rinsing rinsing Original colour with persulphate

Purple; original colour on

Positive

IDENTIFICATION OF REACTIVE DYES ON CELLULOSIC FIBRES-Ill 119

TABLE 2 Behaviour of Reactom Dyes*

Brilliant Red Brilliant Red Blue 2RLD Blue 2GL Turquoise Yellow RL GL 2B (C.I. Reactive (C.I. Reactive Blue GL.

(C.I. Reactive (C.I. Reactive (C.1. Reactive Blue 84) Blue 83) (C.I. Reactive Orange 48) Red 91) Red 90) (formazan ; (formazan ; Blue 85)

Test (monoazo) (monoazo) (monoazo) copper-complex) copper-complex) (phthalocyanine) Boil for 2 min in 5% Very slight LC Very slight LC Very slight LC Slight LC LC (GS 3) LC (GS 3) NaOH (Clayton) (GS 4-5) (GS 4-5B) (GS 4-5) (GS 3-4) . _ .

Colour is greener when in alkali c No staining of white cotton +

Hoechst solvents test +- Completely resistant (no LC) +t Some LC (GS 3-4) + Acid crossdyeing test Slight LC Much LC Much LC Some LC Some LC LC (GS 2-3)

SW (GS 3) (Bode) (GS 4)

Formosul G Permanently Pale yellow Yellow Permanently Permanently Purple then (Clayton) decolorised No change with No change with decolorised decolorised decolorised

with persulphate

Unchanged with persulphate Unchanged with persulphate decolorised Pale greenish blue with persulphate

colour on rinsing

(GS 3-4) SW (GS 2)

(GS 3) 'S"w"& 1) Slight SW (GS 4) (GS 1-2) SW (GS 1) SW (GS 3)

persulphate persulphate Very pale blue

Acid stannous chloride c- Yellower but not completely reduced -++- Slowly decolorised- +Navy blue then (FH)

Alkaline dithionite Violet ; original (Thumm and Benz) Conc. HNO, and acid stannous chloride (FH) Positive

Reactive Blue 85) ; the other two dyes (C.I. Reactive Blue 83 and 84) are listed as formazan copper complexes. These interesting dyes are derived from the parent dye (11):

'GS =Grey Scale LC =LOSS of colour SW =Staining of wool

moderately good. The resistance to Bode's acid cross-dyeing test varied widely with respect both to staining on to white wool and to loss in depth. The presence of copper in the two blue formazan dyes was detected by the procedure described above. As these dyes contain an azo linkage, they were permanently decolorised by reducing agents.

Amaryl and Amaryl X Dyes These two ranges of reactive dyes are manufactured by Amar

Dye-Chem. Ltd (Bombay). The chromogens are listed in the Colour Index, and the Amaryl dyes are thought to be chloro-

I co a: HHNo/o where R = ~ c o o H ' I1 I

N, C //N I R

COONa or CN

The results of the tests are shown in Table 2. triazines (12). No information is available about the constitution of the Amarvl X dves.

The resistance of the three monoazo dyes to boiling sodium hydroxide was excellent, but that of the three blue dyes was only

The results of the tests with these dyes are given in Tables 3 and 4. Five dyeings from each range were tested.

TABLE 3 Behaviour of Amaryl Dyes*

Brilliant Yellow R Brilliant Red EB Magenta B Blue BR Brilliant Blue R

(C.I. Reactive (C.I. Reactive (C.I. Reactive ((2.1. Reactive (C.I. Reactive Yellow 44) Red 73) Violet 13) Blue 56) Blue 55)

Test (azo) (azo) (az0) (aZ0) (anthraquinone) Boil for 2 min in 5% NaOH Redder Yellower Yellower Slightly redder Slightly redder (Clayton) t No loss of colour +

c No staining of white cotton -+ Hoechst solvents test Slight LC Very slight LC Slight LC Very slight LC Very slight LC

(GS 4) (GS 4-5) (GS 4) (GS 4-5) (GS 4-5) Acid cross-dyeing test mode) Much LC (GS 2) Much LC (GS 2) Much LC (GS 2) Slight LC (GS 4) Much LC (GS2)

Slight SW (GS 4) SW (GS 3) sw (GS 2) Slight SW (GS 4) SW (GS 3) Formosul G (Clayton) Decolorised Decolorised Decolorised Yellow Orange

Very pale yellow Pale orange with Very pale orange No change with Very pale blue with persulphate persulphate with persulphate persulphate with persulphate

decolorised No change with Blue with Acid stannous chloride (FH) Permanently As above As above Slowly decolorised Decolorised

persulphate persulphate Alkaline dithionite Orange brown (Thumm and Benz) Dull blue on

rinsing Original colour with persulphate

*GS -Grey Scale LC =Loss of colour SW =Staining of wool

120 JSDC MARCH 1972; JORDINSON AND LOCKWOOD

Test Boil for 2 min in So/ , NaOH (Clayton)

Hoechst solvents test

Acid cross-dyeing test (Bode)

Formosul G (Clayton)

Acid stannous chloride (FH)

Brilliant Yellow 5GX

(C.I. Reactive Yellow 45)

(azo) Much LC (GS 2) f

Very slight LC (GS 4-5) Very slight LC (GS 4-5) Very slight SW (GS 4-5) Permanently decolorised

As above

TABLE 4 Behaviour of Amaryl X Dyes*

Brilliant Orange RX Brilliant Red 6BX

(C.I. Reactive (C.I. Reactive Orange 37) Red 76)

(am) bzo) Much LC Much LC (GS 2) (GS 2)

-+ -No staining of white cotton Very slight LC No LC (GS 4-5) Slight LC (GS 4R) LC (GS 3B)

Slight SW (GS 4) sw (GS 2)

Decolorised Pale yellow Pale yellow with persulphate persulphate

Pale orange with

As above Decolorised Pale orange with persulphate

Alkaline dithionite (Thumm and Benz) Conc. HNO, and acid stannous chloride (FH) *GS =Grey Scale LC =Lo89 of Culour SC =Staining of Cotton SW =Staining of Wool

Navy Blue RX (C.I. Reactive

Blue 59) (am)

LC (GS 2-3) Slight SC Very slight LC (GS 4-51 LC (GS 3 4 )

SW (GS 2-3)

Decolorised Pale yellow with persulphate

As above

Turquoise Bluc 3GX

(C.I. Reactive Blue 5 8 )

(phthalocyanine) LC (GS 3)

No SC LC (GS 3-4)

Very slight LC (GS 4-5G) Very slight SW (CS 4-5) Purple then pale green Pale greenish blue with persulphate Purple then decolorised Pale greenish blue with persulphate Purple; original colour on rinsing

Positive

The Amaryl dyeings were fast t o boiling 5 % sodium hydroxide, thus resembling early types of reactive dyes, e.g. Procion H and Cibacron. However, the Amaryl X dyeings had poor resistance to boiling alkali, although they were somewhat faster t o acid cross-dyeing than the Amaryl dyeings.

Calcobond Dyes This interesting range of reactive dyes was introduced in 1965

by American Cyanamid CO., although for patent reasons the dyes are not offered for sale outside the U.S.A. The chromogens used are given in the Coloiir Index. All the previously mentioned ranges of reactive dyes require alkaline conditions to bring about

reaction between dye and fibre, but Calcobond dyes require a n acidic catalyst. Furthermore, dry heating is necessary t o induce reaction with cellulose. In the reaction, the methylol groups in the reactive dye molecule condense with the hydroxyl group in cellulose (13) :

Calcobond dyes have low substantivity for cellulosic fibres and are applied either bY padding or by Printing in the Presence of ammonium chloride (catalyst). The material is cured by heating for 1-2 min a t 160-175"c, followed by washing-off to remove unfixed dye.

DNHCH,OH + HOCell-+ DNHCH,OCell + H,O

Dyeings of six of this range of dyes were tested (Table 5 ) .

TABLE 5 Behaviour of Calcobond Dyes*

Blue B Turquoisc BN Yellow 3G Orange 2R Red 3B Navy Blue 2G (C.1. Reactive (C.T. Reactive (C.I. Reactive (C.I. Reactive (C.I. Reactive (C.I. Reactive

Yellow 60) Orange 49) Red 92) Blue 87) Blue 86) Blue 88) Test (monoazo) (monoam) (monoazo) (disazo) (anthraquinone) (phthalocyanine)

Boil for 2 min in 5% No LC; Redder Much LC Much LC Much LC Some LC Much LC NaOH (Clayton) (CS 2R) (GS 29) (GS 1-2) (GS 3 4 R )

Hoechst solvents test Slight LC Slight LC Some LC Slight LC Some LC Some LC

(GS 1)

(GS 4) (GS 4R) (GS 3 4 ) (GS 4R) (GS 3-4) (GS 3)

_____ _---, c No staining of white cotton

Acid cross-dyeing test Much LC (GS 1) Much LC (GS 1) Much LC (GS 1) Much LC (GS 1) Much LC (GS 1) LC (GS 3) (Bode) sw (GS 2) sw tGS 1) SW (GS 1) sw (GS 1) sw (GS 1-2) sw (GS 2) Formosul G Permanently Duller and Very pale yellow Permanently Pale brown Purple then (Clayton) decolorised redder then No change with decolorised Very pale blue greenish blue

decolorised persulphate with persulphate Faint blue with (permanently) persulphate

Acid stannous chloride As above Permanently Permanently Pink then (FH) decolorised decolorised decolorised

(permanently)

Alkaline dithionite (Thurnm and Benz)

Purple then yellow Faint blue with persulphate

Orange brown Dull blue on rinsing Original colour with persulphate

Purple then decolorised Pale greenish blue with persulphate Purple: Original colour on rinsing

Conc. HNO,, and acid stannous chloride (FH) 'CS -Grey Scale LC =Loss of colour SW =Staining of wool

Positive

IDENTIFICATION OF REACTIVE DYES ON CELLULOSIC FIBRES-Ill 121

The general resistance to the Hoechst solvents test was in line with that of other reactive ranges, although in no case was the pattern completely fast. The dyeings were not fast to Bode's acid cross-dyeing test or to 5% boiling sodium hydroxide (except for C.I. Reactive Yellow 60). This behaviour differs from that of other classes of reactive dyes on cotton.

Solidazol N Dyes In 1968 Cassella introduced a further range of reactive dyes

for the dyeing or printing of cellulosic fibres-the Solidazol N dyes (14). At present, the range is somewhat limited and consists of azo dyes, but the reactive system employed has not been disclosed.

Dyeings on cotton of three of these dyes were examined (Table 6). Their behaviour is similar to that of the Solidazol prints tested earlier (2), except towards acid cross-dyeing, where the original Solidazol dyes showed much greater staining of the white wool. Incidentally, Solidazol Brilliant Blue FBR (1) resists both boiling 5 % sodium hydroxide and the acid cross- dyeing test.

Identification of Black Reactive Dyeings Six more black reactive dyeings (or prints) on cotton have been

examined and differentiated by the detailed procedure given in part I1 (1). The results (Tables 7 and 8)* classify three blacks in Table 7B, and, of the other three, one (Remazol Black RL) fell into Table 8A and the other two into Table 8B.

"The numbering of Table 7 (A and B) and Table 8 (A and B) corresponds exactly to that used in the relevant tables in Part I 1 ( I ) . The results of tests for metals are, however, included for the first time.

Test Boil for 2 min in 5% NaOH (Clayton)

Hoechst solvents test Acid cross-dyeing test (Bode)

Formosul G (Clayton)

Acid stannous chloride (FH)

TABLE 6 Behaviour of Solidazol N Dyes*

Brilliant Orange N-GR

Much LC (GS 1)

4- N O Very slight LC- (GS 4 5 ) Slight LC (GS 4) Slight SW (GS 41 Decolorised Faint yellowish brown with persulphate Dull orange brown then decolorised (permanently)

Brilliant Red N-3B

Much LC (yellower in alkali)

staining of white Very slight LC (GS 4-5) Slight LC (GS 4) SW (GS 3)

Decolorised Pale yellowish brown with persulphate Decolorised Pink with persulphate

(9s. 1)

Brilliant Rubine N-B

Much LC (much yellower in alkali) (GS 1)

cotton -+

Decolorised Pale yellowish brown with persulphate Decolorised Pink with persulphate

*GS =Grey Scale LC =Loss of colour SW=Staining of wool

The results of the present work and those reported earlier (1) can be summarised as follows :

Table No. of dyes IA 2 7B 6 8A 5 SB 1s

Procion Supra Black H-BP was originally listed as C.I. Reactive Black 10, but was later changed to C.I. Reactive Black 20, under which name it has already been tested and placed in Table 7B (1).

TABLE 7 Black Reactive Dyes Withstanding* 2-min Boil in 5% NaOH

Conc. nitric acid spotting Conc. sulphuric acid Reduction

dilution chloride)

C.I. stain on steep test (acid Conc, hydrochloric Reactive filter on stannous acid spotting

Commercial name Black Chromogen pattern paper extract (A) Dyes that show little or no mining of wool in the acid cross-dyeing test (Bode), i.e. rating 4, 4-5 or 5 on Grey Scale for Assessing Staining

NO DYES IN THIS CATEGORY

(B) Dyes that show definite staining of wool in the acid cross-dyeing test (Bode), i.e. rating <4 on Grey Scale for Assessing Staining Cibacron Black 2PD 10 Disazo Reddish Bluish Dull Blue Bright red, Slightly

(copper-complex) black grey violet then yellower

Reactofil Black BL 24 Monoazo Slightly Dull Pale Unchanged Slowly Slightly (1 :2 chromium- redder purple violet in tone decolorised redder complex)

decolorised

Levafix Black PG 26 Azo Greenish Purple Bluish green Bluish green Bright red, then Unchanged black decolorised

*Effect on pattern ratingX4 on Grey Scale for Assessing Change in Colour

TABLE 8 Black Reactive Dyes not Withstanding* 2-min Boil in 5% NaOH

Conc. nitric acid spotting Conc. sulphuric acid Reduction

stain on steep test (acid C.I. Reactive filter on stannous Conc. hydrochloric

(A) Dyes that show little or no staining of wool in the acid cross-dyeing tests (Bode), i.e. rating 4, 4-5 or 5 on Grey Scale for Assessing Staining Commercial name Black Chromogen pattern paper extract dilution chloride) acid spotting

Remazol Black RL 31 Disazo Dull green Pale brown Green Red Bright red, then Purple (copper-complex) with purple decolorised

(B) Dyes that show definite staining of wool in the acid cross-dyeing tests (Bode), i.e. rating 1 4 on Grey Scale for Assessing Staining rim

Amaryl Black GX 27 Azo (chromium- Reddish Violet Violet Violet Pale greenish Slightly complex) black grey (on warming) redder

Elisiane Grey BJLX 25 Monoazo Violet grey Pale violet Dull bluish Violet Decolorised Violet (1 :2 chromium- with purple red (on warming) complex) rim

*Effect on pattern rating <4 on Grey Scale for Assessing Change in Colour

122 JSDC MARCH 1972; CORRESPONDENCE

Conclusions TABLE 10 Six more ranges of reactive dyes have been tested. The Hoechst

solvents test remains an excellent means of characterising reactive dyeings on cellulosic fibres, as, with almost every dye examined, resistance to the test was satisfactory. Use of Bode’s acid cross-dyeing test (2) and the boiling sodium hydroxide test (3) was continued, for further differentiation of specific reactive dyes based on their different wet-fastness properties. Reducing agents (Formosul G and acid stannous chloride) were again useful for determining the nature of the chromogen. The Thumm and Benz test (4) was again successful in distinguishing both phthalocyanine reactive dyeings and anthraquinone reactive dyeings. Table 9 summarises the behaviour of the six ranges of reactive dyes examined with (a) boiling 5 % sodium hydroxide, (h) Hoechst solvents and (c) acid cross-dyeing.

TABLE 9 Behaviour of Dyeings in Three Tests

Boiling 5% Hoechst solvents Acid cross- Range NaOH test dyeing test

Cibacron Pront Moderately Resistant Not resistant

React ofil Resistant Resistant Variable

Amaryl Resistant Resistant Variable Amaryl X Not resistant Resistant (except Variable but

than Amaryl Calcobond Not resistant Not completely Not resistant

Solidazol N Not resistant Resistant Fairly good

resistant (much staining of white wool)

(except blues) (except blues) staining of white wool

turquoise) more resistant

(except yellow) resistant

resistance

The detailed scheme (I) for differentiating between 25 black reactive dyes on cotton is extended to include 6 more black dyes based on tests a and c above.

Table 10 summarises the results of tests for metals in the dyeings or prints dealt with in this paper.

Presence of Metals

Chromogen as stated in Metal

Commercial name C.I.Reactive Colour Index found Reactofil Black BL Black 24 Monoazo Chromium

(1 :2 chromium- complex)

(1 :2 metalcomplex)

(coppercomplex)

(copper-complex)

Elisiane Grey BJLX Black 25 Monoazo Chromium

Amaryl Black GX Black 27 Azo Chromium Reactofil Blue 2GL Blue 83 Formazan Copper

Reactofil Blue 2RLD Blue 84 Formazan Copper

Cibacron Black 2PD Black 10 Disazo Copper Remazol Black RL Black 31 Disazo Copper

We thank the many organisations that supplied dyeings or prints of reactive dyes for this work.

References I Jordinson and Lockwood, J.S.D.C., 86 (1970) 524. 2 Idem, ibid., 84 (1968) 205. 3 Clayton, ‘Identification of Dyes on Textile Fibres’ (Bradford :

4 Thumm and Benz, Amer. Dyestuff Rep., 55 (1966) 15. 5 Burdett. J.S.D.C.. 80 (1964) 370.

Society of Dyers and Colourists, 2nd revised edn, 1963).

6 Hoechst-Cassella ’Dyestuffs’Ltd, private communication. 7 Stead, Colourage Annual, (1969) 69. 8 Beech, ‘Fibre Reactive Dyes’ (London: Logos Press Ltd. 1970), - .

p. 181.

I0 ‘Colour Index’ (Bradford: Society of Dyers and Colourists; 3rd edn, 1971).

I 1 Abrahart, ‘Dyes and their Intermediates’ (London: Pergamon Press Ltd, 1968), p. 160.

12 Siegel, Chimia Supplement ‘Synthesis and Reaction Mechanisms in Colour Chemistry’ (1968) 100.

13 McCleary, Cate, Fordemwalt and Loffelman, Amer. Dyestriff Rep., 56 (I 967) 28.

14 Shenai, Colourage Annual, (1969) 131.

9 Feess, Melliand Textilber., 51 (1970) 197.

Correspondence The Editor does not hold himself responsible for the opinions expressed by correspondents

Further Considerations of the Potentialities of the Hank-dyeing Machine A the Light of Operational Mass-transfer Processes

The letter (1) from Burley et al. contains two interesting

(i) That level dyeing can be obtained in a hank-dyeing machine of capacity 500 Ib in a time of 60 min using a dye with a time of half- dyeing of 9 min and a time of half-levelling of 120 min if the rate of flow through the yarn is not less than 28 ft3/min or 175 gal/min.

(ii) That such a figure is considerably in excess of the rate of flow operating in ‘modern hank-dyeing machines’ and would be expected to require uneconomical power inputs and to cause hank damage.

This leads the authors of the letter to conclude that ‘the limitations of design concept of hank-dyeing machines will prevent further progress in making the machines more productive’. This conclusion is demonstrated to be valid for hank-dyeing machines based on the Hussong-circulation principle, as described earlier (2).

statements:

HEATING AND PiIOPLLLER C W U N G COILS

GSH-patented flow through top-hank support poles