762 FILSON AND SPEAKMAN- RECLAMATION O F FIBRES FROM RAGS- 111 J.S.D.C. 74

Conclusions There is obviously a need for a fastness-to-

weathering test to supplement or replace light- fastness testing where fabrics are to be exposed in the open air. The destructive effects of outdoor exposure vary widely from place to place and at different times of the year.

Exposures can be made in the open air or in a weathering lamp, and in either case can be assessed either against specially selected weathering standards exposed simultaneously under identical conditions or against the IS0 Light-fastness Standards exposed simultaneously but protected from water (rain, dew, or artificial spray) by glass

or preferably polymethacrylate resin, or by a mechanical device if a lamp is used. DYEHOUSE DEPARTMENT

I M P E H I A L CdEMICAL INDUSTRIES LTD. DYESTUFFS DIVISION

HEXAGON HOUSE

(Reeciucd 9thS'eptember 1958) MLVCHESTER 9

References Butterworth, E., and Guthrie, J. G., J.s.D.c., 71, 587

ICI, Techrrical I,rformatiori, Dyehouse No. 405 (1957)*. Niederhauser. J. P.. Teinterr. 21. 456 (195AI: Co7mdion

(1955).

, --, ~~- ~ ~ ~ ~ . , . ~. ... . . Textile J., 73, 47 77th Sept. 1956).

Brunnschweiler, E., Textil-R nd., 13, 226 (April 1958). 5 ICI, Technical Itiformation, ayehouse No. 266 (l955)*.

"Weathering I7astiie6s- Vat and Azoic Dyestuffs."

COMMUNICATION

Reclamation of Fibres from Rags 111- Action of Hydrazine on Terylene

A. FILSON and J. B. SPEAKMAN

The extent to which Terylene is attacked by 2% solutions of hydrazine in various alcohols a t 100'~. is closely, but inversely, related to the heats of mixing of hydrazine and the alcohols. With glycerol and ethylene glycol the heat, of mixing is high, and it has been shown that ethylene glycol forms a well defined 1 : 1 complex (m.p 9 . 2 ' ~ ) with hydrazine. Dilute solutions of hydrazine in these solvents contain little free hydrazine, and it is not surprising, therefore, that they cause little degradation of Terylene in 40 min. at 1 0 0 " ~ . Conversely, the most rapid destruction of Terylene is brought about by solutions of hydrazine in less reactive solvents, such as toluene and isoainyl benzyl ether. Such solutions have the additional merit of discriminating sharply between wool and Terylene, thus allowing the former to be recovered - - from mixtures for re-use.

In Part I1 of this series of papers it was shown that, when wool and Terylene are treated with a 2% solution of hydrazine in butanol for 60 min. a t 100°c., the wool suffers little damage but the Terylene is reduced to powder l. Wool undergoes severe damage in an aqueous solution of hydrazine a t 100°c., and butanol was chosen as solvent with the object of restricting attack to the surface of the wool fibres2. As soon as it had been shown that the but,anol solution of hydrazine could be used to recover wool from mixtures of wool and Terylene, further experiments were carried out with solutions of hydrazine in other solvents. The object of the work was to discover the principles on which the selection of a solvent for use in commercial processes should be based.

Experimental MATERIALS

(a) HYDRA z I N E- Anhydrous hydra z i n e (99.6y0), supplied by Whiffen & Sons Ltd., was used without further purification.

( b ) TERYLENE-A spun yarn (2127s worsted count), composed of 4-denier filaments, was purified by extraction for 12 hr. each with alcohol and ether in a Soxhlet apparatus. The yarn was then stored in the humidity room (65% R.H., 22.2"c.).

(c) WOOL- A 2132s worsted yarn, made from 64s merino wool, was purified in the same way as the Terylene yarn.

(d ) SOLVENTS- Methanol, ethanol, n-propanol, and n-butanol were dried over calcium and dis- tilled in contact with the metal. Toluene, which was sulphur-free, was redistilled before use. Benzyl alcohol, ethylene glycol, glycerol, ethanol- amine, triethanolamine, and isoamyl benzyl ether were redistilled under reduced pressure.

Procedure and Results 1 . TREATMENT OF TERYLENE YARN WITH SOLUTIONS

OF HYDRAZINE IN VARIOUS SOLVENTS

The Terylene yarn was wound in 30-yd. hanks (1.7-1.8g.), each of which was treated with a 2% (vol./vol.) solution of hydrazine for 7 hr. a t 50°c., or 40 min. a t 100°c., in a sealed, evacuated tube, using a liquor ratio of 30 : 1. After treat- ment, the yarn was washed in running water

Solvent

None (untreated) Methanol ... Ethanol ... n-Propanol . , . n-Butanol . . . Benzyl alcohol.. . Ethylene glycol Glycerol ... Ethanolamine , . .

Triethaiiolamine

TABLE I Breaking Load (g.) of

Yarn treated at 50"c. 1 OOOC .

... I600 1590

... 475 344

... 330 216

... 472 156

... 500 42

... 970 300

... 1560 1350

... 1620 1515

... - Destruction in

... - 680 < 10min.

Now. I068 FILSON AND SPEAKMAN- RECLAMATION OF FIBRES FROM RAGS- I11 763

overnight and then dried in vacuo over anhydrous calcium chloride. The breaking load of the treated yarn was determined with 50-cm. lengths on the Uster machine, and each of the results given in Table I is the average of 20 tests. During the course of the work 200 tests were carried out on the untreated yarn, and the average breaking load was found to be 1 5 8 0 g . , with a coefficient of variation of 7.6%.

2 . TREATMENT OF TERYLENE YARN WITH SOLUTIONS OF HYDRAZINE DJ MIXTURES O F 12-BUTANOL AND

ETHYLENE GLYCOL OR GLYCEROL

The experiments were carried out a t 1OO"c. under the same conditions as above, and the results are shown in Fig. 1.

I .6

x 103

I .4

I .2

I .o

ti

f - 0.8

c 3 QJ L m

0.6

0.4

0.2

0 20 40 60 80 100 Concn. of butanol, yo vol./vol.

x-x -X Butanol-glycerol O--O--O Butanol-glycol

FIQ. 1

3. TREATMENT OF TERYLENE YARN WITH A SOLUTlON O F HYDRAZINE IN ETHYLENE GLYCOL OR GLYCEROL, FOLLOWED BY TREATMENT WITH A

SOLUTION OF HYDRAZINE IN ?%-BUTANOL

After hanks of yarn had been treated with a 2% (wt./vol.f solution of hydrazine in ethylene glycol or glycerol for 40 min. a t 100"c., under the same conditions as before, they were washed, dried, and then treated for different times at 10O"c. with 29.6 (wt./vol.) solutions of hydrazine in n-butanol. For reference purposes, other hanks were merely treated with the solution of hydrazine in n-butanol. The treated yarns were washed, dried, and tested

Tune of Treatment in

Butanolic Hydrazine

(min.) 0 8

16 24 32 40

TABLE I1 Breaking Load (g.) of Yam

Pretreated Pretreated Not with with pretreated

Ethylene Glycerol Glycol 1480 1540 1500 539 760 800 232 301 316 149 178 186 91 107 115 44 55 64

in the usual manner, and the results are given in Table 11. 4. FREEZING POINTS O F MIXTURES OF HYDRAZINE

AND ETHYLENE GLYCOL

A series of solutions of hydrazine in ethylene glycol were prepared for freezing-point deter- minations. Each solution was introduced into a test-tube containing an alcohol thermometer and a hand-stirrer. The tube was mounted within a larger tube, so that it was separated by an air- space from the freezing mixture of solid carbon dioxide and ethanol, which was itself contained in a Dewar flask. Supercooling was encountered in only a few cases, when the concentration of hydrazine was more than 70% (wt./wt.), and the freezing-point diagram is shown in Fig. 2.

10

0

ci -- c ._ % - I 0

I e

M .-

Y

-20

- 30 0 20 40 M, 80 100

Concn. of hydrazine. % wt./wt.

FIQ. 2

5. HEATS O F MIXING O F HYDRAZINE WITH VARIOUS SOLVENTS

Hydrazine (0.2 mole) was added to the stirred solvent (0.5 mole) in a Dewar flask over a period of 45 sec., the rise in temperature being noted on a thermometer graduated in tenths of a degree Centigrade. After the solution had cooled to the original temperature, the temperature rise was duplicated by passing a measured current through' a calibrated nichrome resistance immersed in the

764 FILSON AND SPEAKMAN- RECLAMATION OF FIBRES FROM RAGS- I11 J.S.D.C. 74

solution. Values for the heat of mixing of hydrazine with the various solvents are given in Table 111.

Solvent

Methanol ... Ethanol ... n-Propanol . . . n-Butanol .=. Benzyl alcohol.. . Ethylene glycol Glycerol ...

TABLE I11 Heat of Mixing at

2 0 . 3 " ~ . 5 0 . 0 " ~ . (cal./niole N,H,,'2.5 moles

of solvent) ... 1650 1460 ... 630 492 ... 350 99

... 2220 1900

... 3320 2875

... 3600 3600

205 - ...

6. TREATMENT OF TERTLENE AND WORSTED YARNS WITH SOLUTIONS O F HYDRAZLNE I N INERT SOLVENTS

Although hydrazine is not readily soluble in toluene and isoamyl benzyl ether, 2% (wt./vol.) solutions can be obtained at raised temperatures below 10O"c. When Terylene yarn was treated with such solutions a t 100"c. , degradation was extremely rapid, being complete in under 10 min. More dilute solutions of hydrazine (O.5y0, wt./vol.) were, therefore, used to follow the rate of degrada- tion of Terylene. In these experiments equal dry weights of Terylene and conditioned worsted yarn (regain 15.6%) were together treated with the solution for a given time a t 100"c., the liquor ratio being 30 : 1. After treatment, the yarns were washed, conditioned, and tested in the usual way. The results are given in Table IV.

TABLE IV

Treatment Terylene Worsted (min.) Yarn Yarn

TOLUENE - 1600 344

8 432 325 16 37 1 330 24 291 280 32 22 1 301 40 < 20 253

~SOAMYL BENZYL ETHER - 1565 325

2.5 600 325 5.0 156 319 7.5 < 20 325

Time of Breaking Load (g.)

7. ANALYSIS OF THE PRODUCTS OF THE REACTION BETWEEN HYDRAZINE AND TERYLENE

When Terylene is treated with a solution of hydrazine in n-butanol a t 100"c., the yarn-form is retained even when the breaking load is reduced to 4% of the original value. Further treatment causes the filaments to break up, fist into fibrils and then into powder. The three stages of degradation were examined in the following way-

(i) Terylene yarn was treated with a 204 (vol./ voL) solution of hydrazine in n-butanol for 40 min. a t 100"c., using a liquor ratio of 30 : 1. When the yarn was washed, dried, and re-weighed, no change In weight could be detected, and the nitrogen content was only 06-0-870. The treated yarn was

readily soluble in phenol, and cryoscopic measure- ments showed the molecular weight to be 915.

(ii) Terylene yarn (1.0000 g.) was treated with 10 ml. of a 5% (vol./vol.) solution of hydrazine in n-butanol for 1 hr. a t 10O"c. The resulting fibrils were fltered off, washed with hot butanol, dried, and weighed (0.8645 g.). When the filtrate was cooled to O'C., a flocculent precipitate separated out. This was filtered off, washed, and dried. Its nitrogen content was 2343%, and the molecular weight, determined as before, was 278 (mol. wt. of terephthalic dihydrazide = 194).. The fibrils were next extracted with hot water, and the residue (0-191Og.) was found to have a nitrogen content of 2.304 and a molecular weight of 685. After the water-soluble material had been recrystallised four times from distilled water, it was found to have the following composition- C 50.4y0, H 5.;2%, N 28.696; theoretical for terephthalic dihydrazide-

(iG) Terylene yarn (0.9517 g.) was treated with 6 ml. of a lo?/, (vol./vol.) solution of hydrazine in butanol for 2 hr. at' 100"~. The reaction product was separated into various fractions as before, and the results obtained are given in Table V.

TABLE V

C 49.5:4, H 5.204, N 28.8%.

Type of Amount of Nitrogen Molecular Material Material Content Weight

(%) (%), Butanol-soluble . . . 6.1 2 1.8 189 Water-soluble . .. 81-4* 27.8 - Insoluble ... 12.5 2.5 580

* B y differencr.

Discussion The most surprising feature of the results is the

small extent to which Terylene is attacked by solutions of hydrazine in ethylene glycol and glycerol, as shown in Table I. Even when mixtures of n-butanol and ethylene glycol or glycerol are used, the protective effect of the polyhydric alcohols is still evident (Fig. 1). The remote possibility that the polyhydric alcohols react with Terylene was eliminated by treating the yarn with a solution of hydrazine in n-butanol after previous treatment with a solution of hydrazine in ethylene glycol or glycerol. As is indicated by the data of Table 11, the rate of degradation of the pretreated yarns is even more rapid than that of the untreated yarn. It seemed likely, therefore, that the protective effect of the polyhydric alcohols was due to complex formation with the hydrazine. This view was confirmed by the form of the freezing-point diagram for mixtures of ethylene glycol and hydrazine. As shown in Fig. 2, there is clear evidence of the formation of a 1 : I complex (34% hydrazine), and when the glycol is present in great excess, as in the solutions used for treating Terylene, it is unlikely that much free hydrazine will be available, even at IOO"c., for attack on the polymer. In accordance with these observations, the extent to which Terylene is attacked by solutions of hydrazine in the alcohols listed in Table I is closely, but inversely, related to the heats of mixing of hydrazine and the alcohols (Table 111).

Xov. 1958 BROOKER AND VITTIIM- DYES FOR PHOTOGRllPHY 7 65

It is obvious from the preceding results that hydrazine will be most effective in destroying Terylene when it is dissolved in a solvent with which complexes are not formed. Ethanolaniine is presumably a solvent of this kind, because the polymer is destroyed with such rapidity (Table I), but a solution of hydrazine in ethanolamine degrades wool a t 100"c. and cannot be used to recover wool from' mixtures containing Terylene. Solutions of hydrazine in toluene or isoamyl benzyl ether do, however, discriminate between Terylene and wool, as shown in Table IV, and the rate of attack on Terylene is very much more rapid than that given by a solution of hydrazine in n-butanol.

chain fission in accordance with the following equation-

-OC0,C6H4C0.0,CH,CH,- -1- N2Ha -+ -0,C0.C8H4,C0,NH.NH2 + HOCHz.CHz-

Ultimately, the polymer should be converted into terephthalic dihydrazide, and the recrystallised aqueous extract from severely degraded Terylene was found to have a composition in good agreement with that of the dihydrazide. TEXTILE CHEMISTRY LABORATORY

THE UNIVERSITY LEEDS 2

DEPARTMENT OF TEXTILE INDUSTRIES

(Received 31st July 1958)

References 1 Atkinson, J. C., and Speakman, J. B., J.s.D.c., 73, 419

Speakman, J. B., T r a m Farocihy SOC., 26, 61 (1930).

men Terylene is attacked by hydrazinej the molecular weight decreases in accordance with the severity of the treatment, presumably owing to

(1957).

EXTERNAL ADDRESS

A Century of Progress in the Synthesis of Dyes for Photography" L. G. S. BROOKER and P. W. VITTUM

There are four main uses of dyes in photography today- (1) as optical or spectral sensitisers, (2) in antihalation and filter layers, (3) as desensitisers, and (4) in the formation of coloured images.

became clear that the longer the conjugated chain between the two nitrogen atoms, the longer the wavelength of the long-wave, and photographically important, band. In 1920 the purple Pinacyanol, obtained from quinaldine ethiodide and form-

1 . SENSITISERS aldehyde, was found to contain a 3C conjugated chain joining the two nuclei (111: D = D' = residue of quinoline nuclei; R = R' = C&,; Z = H).

The optical or spectral sensitisers confer sensi- tivity on the photographic emulsion in regions in

a wide variety of dyes behave in this manner, those / I I I I C=CH-CH=C I 1856 the first cyanine was obtained by Greville N / Williams by the action of alkali on a crude ff

cyanine, rendered a photographic emulsion In the years immediately fo l lohg , Kiinig pre- sensitive to light of the range absorbed by the dye, Pared dyes (111: D = D') containing benzo- although this is a simplified picture and the thiazole and benzoxazole rings, which rapidly absorption of the dye when adsorbed on the replaced the quinoline derivatives as Useful halide particles is different from its usual lnolecular sensitisers. Later, dyes were prepared containing absorption. It was discovered that the presence chains of 5 C and 7 C, t'he benzothiazole dye of the of lepidine in the quinoline was necessary for the latter tYPe being an infmred sensitiser. In the formation of cyanine (I). years 1925-1910 a variety of methods for preparing

both symmetrical (D = D'), unsymmetrical f-\ ,,/-\ L-N /\,,'\ (D f D'), and chain-substituted (e.g. Z = CH,)

dyes were discovered, and a range of heterocyclic nuclei incorporated into cyanine dyes. Cyanine

X- R X- dyes may be considered as resonance hybrids of the two possible canonical states, and the colour of the dyes has been related to the basicity of the

The mixed quinaldine and quinoline salts gave the nuclei forming the ends of the dye molecule. In red isocyanines (11), and these dyes were used in 1934 a new class of polymethin sensitisers was the first decade of this century to confer, on a discovered by Kendall, the merocyanines, which silver iodobromide emulsion, sensitivity in the are vinylogues of amides, e.g. IV, in which green region of the spectrum. resonance is between an uncharged and a dipolar

The outbreak of the 1914 war caused Pope and form. A wide range of nuclei has been used at the his co-workers to investigate the synthesis and acidic end of the merocyanine. structure of cyanine dyes, and the structure of the More recently it has been shown that good simpler dyes was placed on a firm footing. It soon sensitisers have a planar or nearly planar structure,

which it would otherwise be insensitive. Although 2 D' / \ / S , /CO-N.C2Hb

in use today are almost entirely cyanine dyes. In I 'ccH='-cH=c \A \.y 'S-c=s

CPHS I R' quaternary quinoline salt. Vogel in 1873 dis- X-

covered that a variety of dyes, including Williams's (111) (IV)

/ ,'-\~ \ /-' -/ + )=( .-

R-N ,>=CH-,\,;N-R R-N,=>=CH \=.

( 1) (11)

Communication No. 1842 from the Eastman Kodak Co Research Laboratories published in Proceedings of the Perkin Centennial (LOWeU Abstracted fromjoumal of Photographie Science, 5, 71-88 (1057) by G. F. Duffin of Ilford Ltd: Mass.: AATCC. 1958), pp. 369-408.

Reuwick Laboratory.

A6