6. Egerton and Morgan, J.S.D.C., 87 (1971) 268. 7. Dilthey and Quint, J. prakt. Chem., (2) 128 (1930) 146. 8. Kearns, Hollins, Khan, Chambers and Radlick, J. Amer.

Chem. SOC., 89 (1967) 5455. 9. Griffiths and Hawkins, Chem. Comm., (1972) 463.

10. Kearns, Khan, Duncan and Maki, J. Amer. Chem. SOC., 91 (1969) 1039; Wasserman, Kuck, Delavan and Yager, ibid., 91 (1969) 1040.

1 I . Wilcox and Stevens, ibid., 84 (1962) 1258; Forbes and Griffiths, Chem. Comm., (1967) 427.

12. Fox, J.S.D.C., 65 (1949) 508. 13. Landolt, ibid., 65 (1949) 659. 14. Bamford and Dewar, ibid., 65 ( I 949) 674. 15. Foote, Wexler and Ando, Tetrahedron Letters, (1965)

41 11. 16. Quannes and Wilson, J. Amer. Chem. SOC., 90 (1968)

6527.

The Behaviour of Disperse Dyes at High Temperatures

WILLIAM McDOWELL

Farbwerke Hoechst AG vornials Meister Lucius & Bnining Frankfurt (Main)-Hoechs t

Investigations on disperse dyes in the vapour phase are described. The various methods of determining the vapour pressure of such dyes at high temperatures are compared. By means of direct spectrophotometric determination, a relation is established between the partial vapour pressure of a disperse dye over its solution in polyester, and its concentration in polyester. I t is shown that the heat-fastness properties of such dyes depend on their vapour pressures, any exceptions being due to the instability of the particular dye under the conditions of testing. Finally, the kinetics of such processes are considered and some attempt is made to analyse practical systems.

Introduction The behaviour of disperse dyes at high temperatures has always been of importance owing to the fastness to subli- mation* required in the domestic and industrial spheres. With the rapid increase in ‘popularity’ of thermofix dyeing, a considerable amount of experimental information has been published on the mechanism (or mechanisms) of thermo- fvration [ 1 - 121 . After considerable discussion about the role of transfer by physical contact between dye particle and substrate [e.g., 71, it now seems to be accepted that, in the absence of large amounts of auxiliaries, dye is transferred through the vapour phase [9]. Since it has long been assumed that fastness to sublimation depends on transfer in the vapour phase, and since recent experimental evidence strongly supports this hypothesis [ l o ] , it was considered that a closer look at modem disperse dyes in the vapour phase might supply information that would complete our understanding of such

*‘Fastness to sublimation includes fastness to dry heat in all its variations.

phenomena. Further, since much quantitative information on older disperse dyes and model compounds had been obtained by Jones et al. [13-171, it was decided to compare vapour pressures as measured by other methods with the data of Jones et al. obtained using effusion methods (both Knudsen and torsion).

Experimental Where a comparison with previous results was possible, e.g. with 1-methylaminoanthraquinone (C.I. Disperse Red 9), the dyes were carefully purified. In other cases the dyes were taken directly from the press cakes, to enable their experi- mentally determined vapour pressures to be correlated with their known behaviour in practical dyeing and testing systems.

The chief method adopted for measuring the vapour pressures was the most direct one available, viz. by spectro- photometric estimation of concentration in the vapour phase. A few mg of dry dye was added to a 10-cm gas cell. The cell was then flushed with nitrogen (to avoid oxidative destruction of dye [ 181 ), evacuated to less than 1 mmHg and melt-sealed.

The 10-cm cylindrical portion of the cell was fitted into two halves of a thick steel cylindrical sleeve, whch was drilled out for the filling tube, so allowing both halves of the sleeve to be pressed tightly together (Figure 1). Copper plates were braised on to the ends of the sleeves, and windows were cut into the plates. The windows were large enough to facilitate alignment of the spectrophotometer beam through the cell. The windows were then sealed by cementing a portion of a microscope slide over the aperture. The two halves of the sleeving were wound with identical lengths of resistance wire, which were then switched parallel to the same transformer. The purpose of the thick metal sleeving, its contact in the middle, and the copper plates covering most of the window surface was to ensure an even distribution of heat over the entire cell and so avoid condensation of dye in the cell.

The filling tube, in which the solid dye was contained, was placed in a separately controlled oven of similar construction which was held some 10 degC lower than the other oven and thus used to control the vapour pressure. Temperatures at the

JSDC May 1973 177

glass surfaces in both ovens were measured by means of fine nichrome-constantan thermocouples with an ice-bath as reference. The cell aggregate was then placed between the collimators in the measuring beam of a modified Beckman DU or a Bausch & Lomb 600 E spectrophotometer using an 1 SP 21 photomultiplier with the output to a Metrawatt Servogor RE 5 1 1 servo-recorder. Four microscope slides were placed in the reference beam to compensate for the reflectance losses a t the four windows of the cell-oven aggregate. In later experiments dyed polyester samples were placed in the lower oven. All spectra were taken after sufficient time had been allowed for equilibrium to be established at each new oven temperature.

I copper plate

I

glass window

lrwing

iktwce wire (lower oven1

Figure I -- Gas cell and oven unit for vapour spectra of disperse dyes

The second method used for measuring the vapour pressure of disperse dyes was the classical transpiration method. Here a constant area of dye (premelted), or dyed material, is exposed at a carefully controlled temperature for a given time to a stream of inert gas (nitrogen). The vapour produced over the surface of the dye (or substrate) is swept away by the carrier gas, collected in a cold trap (Figure 2) , from which it can later be extracted and spectrophotometri- cally estimated [ 181. Since the carrier stream is not saturated with dye vapour, the measurement is repeated at various rates of flow of carrier gas and the results are extrapolated to zero rate of flow.

I Pt 103

‘ z z d ~ w g ~ m p o c i t y heating jacket thermistar W’C

Figure 2 - Transpiration method for measurement of vapour pressure ( P o = vapour pressure of dye; P = pressure of gas; ID = no. of moles o f dye passed; nc = no, of moles o f gas passed)

178 JSDC May 1973

Results Figures 3 and 4 show typical examples of the vapour spectra of some commercial disperse dyes. I t is interesting to note tha t there is a considerable hypsochroniic shift in going from the solution to the vapour spectrum (analogous to the hypsuchro- mic shift found on going from solid dye to its solution in a solvent). The absence of double peaks in some instances might be taken as evidence of association, bu t such an hypothesis is in n o way compatible with the fact that the observed phenomenon appears t o be in n o way dependent on temper- ature, as would be the case if it were due to association. The total vapour data for a series of modern commercial dyes are given in Table I .

380 LOO 450 500 600 700 Wavelength, nm

Solution spectra 10-cm cell

Figure 3 - Typical vapour spectra of disperse dyes [ A : Samaron Yellow 3GL (C.I. Disperse Yellow 54); B: 7 amaron Blue FBL (C.I. Disperse Blue hO)]

With the standard dye, 1-me thy laminoan thraquinone, i t was necessary to transform the measured transmission spectra in to exact measurements of vapour pressure or concentration. To d o this i t was necessary to determine exactly the extinction coefficient of the dye in the vapour phase. Experience shows that, although the wavelength of maximum absorption of a compound varies significantly with change in dielectric con- stant of the surrounding medium, the integral extinction coefficient (the total area inside the extinction or absorbance curve) of the compound remains in many cases largely unchanged.

90

80

70

60

&? 50

._ = LO : ' - 3 0

Q 3 c m

m L

20

10

L V., u

2 0.5

0.3

a2

01

1 I I I

- - (direct from - -

-

- 1 I "

380 LOO 500 600 700 Wavelength, n m

Solution spectra 10-cm cell

Figure 4 - Typical vapour spectra of disperse dyes ( A : Samaron Golden Yellow HGL (C.1. Disperse Yellow 68); B: Samaron Violet HFRL (C.I. Disperse Violet 31)/

This means in practice that, if the band width remains the same with a bathochromic or hypsochromic shift, the mass or molar extinction coefficient remains virtually unchanged. (Molar extinction coefficients [cmolar] are more popular with organic chemists, who are more likely to know the exact constitution of the compounds with which they are dealing, whereas those workers concerned solely with the physical measurements on such compounds prefer the use of mass extinction coefficients [E,,, , cm2/g] which assumes for convenience unit solid density and expresses the coefficient as the absorption of the solid material instead of the absorption of a unimolar solution. The mass coefficients are in any event of more practical value since such compounds are usually sold by weight and not as moles.)

Although the band width in this case remained much the same despite a hypsochromic shift from 501 nni to 460 nm, it was nevertheless considered advisable to check by independent means the extinction coefficient in the vapour phase. To do this 0.1 mg of the dye was weighed into the cell, which was sealed as before and placed with attached ovens in the measuring beam of the spectrophotometer. The temperatures of both ovens were increased until no further decrease in transmission was observed, showing that all dye was now present in the vapour form. (It was important to keep the

amount of dye weighed into the cell to a minium so that unsaturated vapour could be produced without having to use too high temperatures. The reason for this will be explained below.) The cell, on cooling (upper oven first), was then opened at the end of the filling tube and filled with dimethylformamide (in which solvent the extinction coeffi- cient of the dye was known), and replaced (with ovens) in the measuring beam of the spectrophotometer, so that a double check could be made on the concentration and thus the exact amount of dye in the cell.

10 1 7

5

ir from effusion data)

I-

; a m >

Figure 5 - Vapour pressure of 1-methylaminoanthraquinone

The mass extinction coefficient (emass) for l-methyl- aminoanthraquinone in the vapour phase measured by this means was 21,500 cm2/g (at A,,, 460 nm) compared with 30,000 cmZ/g (at A,,, 501 nm) for the dye in solution in dimethylformamide. Using the Lambert-Beer law and the former value of extinction coefficient to convert the spectral data at the various temperatures of measurement into concen- tration data, a somewhat different relation between vapour concentration and temperature was found for this standard dye (Figure 5 ) than that reported by Jones and Seddon [ 151, based on the vapour-pressure data of Bradley et al. [ 131. That the difference should be due to association in the vapour phase, as has been reported for some dimethylaminoazo- benzene derivatives [ 16, 171, seems very unlikely, since there is no evidence of this in the spectra, despite a IOO-fold increase in vapour concentration measured. A desorption isotherm at

JSDC May 1973 179

TABLE 1

Vapour Data for Series of Modem Disperse Dyes

Dye No. 1 2 3 4 5 6 7 8 9

Commercial Name C.I. Disperse Samaron Golden Yellow HGL Yellow 68 Samaron Yellow 3GL Yellow 54 Samaron Yellow H3GL Yellow 64 Duranol Red GN ( I-MethylaminoAQ) Red 9 Saniaron Pink FBL Red 60 Samaron Violet HFRL Samaron Blue FBL Blue 56 Samaron Blue HBL Blue 95 Samaron Blue H3R Blue 152

Violet 3 1

Dye No. 1* 2 3 4 5 6t 7 hma,DMF 400 438 435 501 517 540 630 A m a x Vapour350 433 430 460 490 505 520 Temp. ("C) Extinction 10 ern vapour at A,,, 160 0.063 170 0.144 180 0.280 0.044 190 0.455 0.1 13 2 00 0.099 0.840 0.167 0.183 210 0.131 0.143 0.100 1.45 0.368 0.223 0.131 220 0.171 0.270 0.187 1.74 0.597 0.270 0.206 230 0.245 0.535 0.339 1.15 0.322 0.351 240 0.345 1.00 0.623 0.413 0.535 250 0.468 1.10 0.642 0.719 260 0.585 0.886 1.08 270 280 Vapour pressure (calc.) (pbar) based on actual vapour spectra 160 44 170 104 15 180 208 39 190 346 64 200 21 650 63 81 210 29 18 14 1150 142 98 31 220 39 34 26 1410 231 120 50 230 57 70 49 462 157 97 240 82 133 91 248 136 250 1 03 164 350 187 260 143 28 5 270 280

'Measured at 380 n m ?Above 220"C, new stable vapour species formed **Dye consists of ca equal amounts of two main isomers

200°C, obtained by placing polyester (dyed to various concentrations by the normal aqueous method) in the lower portion of the cell, proved linear (Figure 6), as did virtually all the sorption isotherms obtained by Jones et al. on cellulose acetate. The concept of association in the vapour phase is also difficult to reconcile with linear isotherms and proven mono- molecular dye in the substrate [12, 191.

The conversion of vapour concentration into vapour pressure (or vice versa) entails applying the equation of state for an ideal gas, pV=nRT, assuming that the hehaviour of the

8** 9 625 613 545 515

0.048 0.097 0.181 0.327 0.45 1 0.680 0.980

0.048 0.154 0.307 0.500

13 27 53 97

137 206 310

22 69

140 232

vapour approaches that of an ideal gas, which in view of the monomolecular nature of the vapour is at least as justified as the assumptions made in determining vapour pressures by the effusion and transpiration techniques, namely that the kinetic theory and ideal gas law also hold for the vapour (for data see Table 1). The transpiration method, although well established as a method for determining the vapour pressures of sub- stances with very low vapour pressures, was more useful as a comparative tool for the relatively high vapour pressures of some dyes, especially the chosen model dye, e.g. vapour

180 JSDC May1973

25

2.0

- . 15

L 0 Y UI 0

z 0

al

- n L

& 5 1.0 0 m 0 z U

0 C

a

'c

i a5 u

0 I

0 1.0 2D 3 Dye originally in polyester, %

Figure 6 - Desorption isotherm o f I-methylaminoanthra- quinone from polyester at 200°C (direct from vapour spectra)

pressure of dye alone and vapour pressure of dye over a given concentration of dye in polyester [18]. Figure 7 shows a linear extrapolation carried out on the model dye, and Figure 8 the results of such extrapolations on dyed polyester in the form of a desorption isotherm. It is interesting to note that the factor between the spectrophotometric and transpiration measurements on pure dye is repeated with the spectrophoto- metric and transpiration measurements on dyed polyester. The inaccuracy in the latter method is inherent in the extrapo- lation, but this is further complicated by the kinetics of vapour production, as will be discussed below. A glance at a log plot of the transpiration data (Figure 9) suggests that a double exponential extrapolation would be just as reliable as the linear one chosen.

Discussion In view of the lively interest in thermofix-dyeing techniques, the many studies on the transfer mechanism in such dyeing systems, and the acceptance of transfer through the vapour phase as the mechanism, it seems somewhat surprising that the initial fundamental work of Jones et al. has as yet not been followed up by other workers in this field. The present work presents a spectrophotometric technique and a transpiration technique for measuring vapour pressures. The spectrophoto- metric technique has the advantage that it is experimentally

simple and rapid, and that it gives a direct measurement. The effusion techniques of Jones et al. and transpiration technique described above are complicated, slower, and involve fewer direct measurements. The spectrophotometric method has the additional advantage that not only can the state of the dye in the vapour phase be directly determined, but any decompo- sition can instantly be noted - a point of no mean importance with modern commercial dyes, as will be seen below. The transpiration method works well for substances with very low vapour pressures, where the rate of production of vapour is of no importance, i.e. vapour can be produced at a rate sufficient to nearly saturate the inert gas stream, thus simplifying the extrapolation to zero rate of flow. The near constancy of the error in the transpiration measurements on pure dye and dye in polyester would therefore seem to suggest that the rate of production of vapour in both cases is of the same order of magnitude. This point has already been made in an analysis of thermofix-dyeing systems [ 181, where it was suggested that the rate of production of vapour, the magnitude of the vapour pressure (and hence of the distribution coefficient) and the rate of diffusion through the diffusional boundary layer [20] were of greater importance at these high temperatures than the rate of diffusion in the substrate.

It was further suggested [18] that the existing data on diffusion coefficients at these high temperatures should be re-examined in view of the difficulty in uniquely defining the boundary conditions in such vapour-phase dyeing systems, and

0'. ' I I

1 5 10 Rate of flow, I/min

Figure 7 - Linear extrapolation with model dye (I-methyl- aminoan thraquinone) at 200°C

JSDC May 1973 181

with an aim t o bringing them more in line with the existing data for aqueous dyeing [e.g., 5 , 211 and dyeing in non- swelling solvents [22] at lower temperatures. If diffusion in the substrate is of only minor importance in themof= dyeing, then i t should not be important in fastness t o sublimation. A considerable amount of experimental data have been published in an attempt t o prove a relation between the rate of diffusion in the substrate (as measured in aqueous high-temperature dyeing) and fastness t o sublimation [5]

0.07

0.06

0.05

0.04

U

m u -

a03 u X

N

Z

E

- 2 a02

a01

0 1 2 3 Dye originally in polyester, %

Figure 8 - Desorption isotherm of l-methylaminoanthra- quinone from polyester at 200°C (transpiration method)

It was suggested that a high fastness to sublimation was due to the kinetics of the process and thus large molecules, which were known t o diffuse slowly in polyester under aqueous dyeing conditions, would possess a higher fastness to sublimation than smaller, fast-diffusing molecules (in N. American terminology the so-called high- and low-energy dyes respectively).

It has already been pointed out [I81 that an increase in molecular size causes a decrease not only in diffusion coefficient but also in vapour pressure, so that the observed parallelism in some instances is not surprising.

It has already been suggested that disperse dyes in polymer substrates form virtually ideal solutions obeying Raoult’s and Henry’s laws with little or no specific interaction between dye and substrate. However, practical experience shows that the introduction of certain polar groups (e.g. CONH, or SO, NH2) greatly increases the fastness to sublimation of a given dye. Attempts to explain this on the basis of hydrogen bonding(or other oriented forces) between the dye molecule and specific groups in the substrate, e.g. carbonyl, overlooked the fact that such forces are extremely dependent on temperature (as

. a2 -

e,

n 0.1 1

0.07

affi

0.03

0.02

- - -

aoh - -

-

0.07 - affi -

0.03

0.02

-

aoh - -

-

oat I 0 5 10 15

Rate of f low, I/min

Figure 9 - Logarithmic plot of transpiration data for 1 -methylaminoanthraquinone at 200°C

opposed to forces of dispersion, induction or coulombic forces and t o a less extent ion-dipole forces).

On the other hand, the introduction of a polar group into a molecule greatly decreases the vapour pressure of the substance itself and, since disperse dyes in general when dissolved in polymer substrates are known t o obey Kaoult’s law (e.g. Figure 6), the fastness t o sublimation should decrease with increase of dye concentration in the substrate, and for a given concentration of any dye be a simple function of the measured vapour pressure of that dye. There is much evidence t o show that the measured fastness to sublimation depends on the concentration of dye present in the substrate [e.g. 101.

To show that the measured fastness to sublimation runs parallel to the measured vapour pressures for a series of disperse dyes, the accurately obtained values of von der Eltz et al. [ 101 for the temperature a t which sublimation commenced (Grey Scale 4) at a standard depth of dyeing were compared with the measured vapour data of the same dyes. T o account for the different sensitivity of the eye to the various dyes sublimed on to the adjacent undyed polyester, the actual vapour data for each dye (absorbance in a 10-cm cell) were multiplied by the reflectance of the white undyed polyester minus the tristimulus value Y (lightness) of a standard 0.3% dyeing of the same dye on polyester. The results of this calculation are plotted in Figure 10, where it can be seen that the more or less parallel curves correspond in their displace- ment as near as can be expected to the gradations chosen by von der Eltz et al. to classify the start of subliniation. This would seem t o indicate clearly that the fastness t o Sublimation of a disperse dye is largely a function of its vapour pressure

Extxf

.< I

0.18 0.19 a20 an ~ 2 2 aax10-3

K

Samaron C.I. Disperse Bleeding on polyester (GS 4) f RTT (std depth) [ 101

1 Blue H3R Blue 95 185 2 Yellow H3GL Yellow 64 1 80 3 Yellow 3GL Yellow 54 175 4 Blue FBL Blue 60 170 5 Pink F B L Red GO 165 6 Blue HBL Blue 95 160

Figure 10 - Relation between vapour pressure and fastness to sublimation of some disperse dyes

and that the kinetics of sublimation (diffusion out of the substrate at, e.g., 200°C) can thus play only a minor role.

Some evidence for this hypothesis can be seen in the fact that the same dye has more or less the same fastness to sublimation on all synthetic-polymer fibres, although the rates of diffusion at these high temperatures would be expected to be different in the various fibres.

Further evidence is seen in the fact that some small fast-diffusing polar dyes, e.g. Samaron Orange HB (C.I. Disperse Orange 13), Samaron Orange HRRE (C.I. Disperse Orange 35) and Samaron Golden Yellow HGL (C.I. Disperse Yellow 68), show good fastness to sublimation because of their low vapour pressures, and, conversely, some large slow-diffusing non-polar dyes, e.g. Samaron Violet HFRL (C.I. Disperse Violet 3 1 ) and Samaron Pink HGG (C.I. Disperse Red 89), are no more difficult to apply by thermofuration than ordinary dyes, because of their relatively high vapour pressures.

There is however a further point which complicates this simple rule-of-thumb relation between fastness to sublimation and vapour pressure, viz. the stability of the dye in the vapour phase. It has already been mentioned that this can readily be seen in the vapour spectrum of the dye. With certain dyes, it was impossible to obtain vapour spectra in the presence of

even traces of oxygen and in some cases even in the total absence of oxygen. Thus it may be concluded that thermal or oxidative instability plays a role in the testing of the fastness to sublimation of some disperse dyes. The products of thermal or oxidative destruction are often colourless or pale yellow (especially with azo dyes) and therefore do not stain the accompanying undyed material, giving the impression that some dyes have better stability to heat than is really the case. Some navy blue dyes with low melting points (which would tend to indicate h g h vapour pressures) are amongst the best examples of dyes that exhibit such behbiour. It should be pointed out that this destruction is only partial. It depends, with thermal destruction, on time in the vapour phase, and, with oxidative destruction, on time and amount of oxygen present in the vapour phase, i.e. the number of collisions with oxygen molecules on passage from substrate to substrate. This means that, in a kinetic process (a fastness-to-sublimation test or thermofix dyeing), a certain proportion of these unstable dyes always reaches the safety of the substrate where they are apparently more stable. In an equilibrium process, e.g. obtaining the vapour spectra, the dye is largely destroyed before equilibrium can be established.

The above in no way limits the usefulness of the fastness-to-sublimation test, since the contamination of the adjacent undyed material is of more practical importance than the very small losses in dye from the dyed material. The terminology 'fastness to sublimation' is still correct since that fraction of a dye that decomposes cannot be said to be subliming. One should, however, bear in mind that there are various factors that can contribute to a given fastness to sublimation (leaving aside for the moment sensitivity of the eye to various colours and ignoring diffusion in the substrate completely). Dyes with poor fastness to sublimation are usually stable with high vapour pressures, e.g. non-polar anthraquinone derivatives. Dyes with medium fastness to sublimation are usually stable dyes with medium vapour pressures, e.g. polar or large anthraquinone derivatives, or slightly unstable dyes with high vapour pressures, e.g. low- meltingpoint azo dyes. Dyes with good fastness to subli- mation can be stable dyes with extremely low vapour pressures, e.g. benzo-thioxanthene derivatives, slightly unstable dyes with low vapour pressures, e.g. highly polar large- molecular-weight azo derivatives, or even very unstable dyes with fairly high vapour pressures. The last mentioned case is purely hypothetical since the loss of colour from the dyed sample would preclude their use in practice.

I t can be said with some certainty that the classification of disperse dyes into low-, medium- and high-energy groups, linking their aqueous dyeing behaviour with their heat-fastness properties, has no physical basis whatsoever, but is a purely empirical classification where sufficient factors cancel each other out to make the system more or less correspond to practicd, experience.

Practical Considerations It is not really surprising that some disperse dyes are unstable in the vapour phase at temperatures of the order of 200°C. Experience from aqueous dyeing of polyester at temperatures between 1 2 0 and 130°C shows in some cases a non-linear build up of pure dye despite 100% exhaustion of the bath (the type of anomalous behaviour readily shown up by instrumental match prediction). Further, with some dyes equilibrium

JSDC May 1973 183

TABLE 2

Effect of Dye Degradation on Measured Sublimation Fastness

C.1. Disperse Fastness Colour rating Tristimulus values difference (staining) X Y 2 (N.B.S. units)

Yellow 68

1 76.40 81.82 47.22 37.8

1-2 79.21 84.30 60.80 26.9

3 83.83 36.83 86.16 8.9

4 84.86 87.13 92.88 4.4

Blue 79

2-3 68.36 7 1.30 91.72 11.3

4- 5 83.81 85.93 97.74 1.65

Red 160

4 84.12 84.79 94.16 3.30

4-5 85.84 87.23 97.39 1.85

desorption isotherms in aqueous solution show that the small quantity of dye desorbed is conipletely or partially destroyed (for example in using up the oxygen in the dyeing vessel). However, such effects are of little consequence in terms of yield in practical dyeing systems, where either the amount left in the dyebath or the amount destroyed in the reductive aftertreatment is usually of greater significance. In thermofix dyeing, the amount of unfixed dye is usually more than that which would be destroyed by heat or oxidation. On the other hand, in fastness testing, where an unnoticeable loss of colour from a dyed material can cause a considerable visual effect on an undyed material, this small amount of dye which might be destroyed can be of considerable importance in decreasing the visual effect on the undyed material and so result in an improvement in the measured fastness property.

Based on measured fastness and using simple Kubelka- Munk theory such effects are demonstrated in Table 2.* I t must be pointed out that the influence of dye stability in the vapour phase on the measured fastness to sublimation is with commercial dyes a very gradual one, since the appearance of the dyed material at very high testing temperatures is a further criterion in their selection as commercial products. However, the point made previously and demonstrated in Table 2 is that

*From reflectance measurements on some randomly chosen dyed and stained samples from fastness-to-sublimation tests, the amount o f dye transferred to the stained sample to give a measured fastness rating was calculated. It can be seen that, since the amounts sublimed necessary to give these ratings are very small, the decomposition of equally small amounts during sublimation could cause a considerable change in the fastness rating.

Undyed Dyed Stained Dyed S taine d Dyed Stained Dyed Stained

Reflectance values a t wavelength (nm) 470 480 490 500

86.6 87.2 87.7 88.0 5.2 6.2 7.4 9.1

47.0 53.1 59.3 65.3 5.1 6.1 7.3 9.0

58.4 63.6 68.6 73.2 4.9 5.8 7.1 8.8

76.6 78.9 81.0 82.7 5.0 6.0 7.2 9.0

81.2 82.6 83.6 86.6

510 520 530 540 Undyed 88.4 88.5 88.8 88.9 Dyed 8.0 6.8 5.7 5.0 Stained 78.1 76.9 75.2 73.6 Dyed 8.1 6.9 5.7 4.9 Stained 86.2 86.2 86.1 86.0

570 580 590 600 Undyed 89.5 89.9 90.2 90.7 Dyed 6.6 9.4 13.5 19.4 Stained 85.0 86.1 87.0 88.1 Dyed 6.5 9.3 13.4 19.3 Stained 87.4 87.9 88.6 89.2

%Stained (on total dyed and stained)

2.8

1.4

0.3

0.1

0.5

0.1

0.2

0.1

the destruction of a small amount of dye during the s u b h a t i o n test can easily cause a unit change in the fastness rating.

Clear evidence of decomposed dye can be obtained by anyone who takes the trouble to investigate the extracts of such tested specimens chromatographically.

* * *

I thank Dr F. Glaser and Dr K. Hoffmann for advice and assistance in obtaining the reflectance data used in the fastness tests and Mr H. Weber, Mrs D. Wagner and Mrs S. Schafer for carrying out the practical work.

(MS. received 2 7 July 19 72)

References

1. Kartaschoff, Helv. Chim. Acta, 8 (1925) 928. 2. Gibson, Du Pant Tech. Bull., (1949) 82. 3. Fourness, J.S.D.C., 72 (1956) 5 13. 4. Schroeder and Boyd, Text. Research J., 27 (1956) 275. 5. Thurner and Wurz, Melliand Textilber., 47 ( I 966) 73, 18’3,

6. Salvin, Amer. Dyestuff Rep., 55 (1966) 490; 56 (1967)

7. Beckniann and Kuth, Melliand Textilber., 48 (1967) 1441. 8. Datye, Kangle and Milicevic, Textilveredlung, 2 (1967)

299,414.

421.

263.

184 ISDC May 1973

9. Bent, Flynn and Sumner, J.S.D.C., 85 (1969) 606. 10. von der Eltz, Seifert and Birke, Chemiefasem, 21 (1971) 2. 11. Gruner and Janousek, J.S.D.C., 85 (1969) 3. 12. Datye, Pitkar and Purao, Textilveredlung, 6 (1971) 593. 13. Bradley, Bird and Jones, Trans. Faraday SOC., 56 (1960)

14. Jones, J.S.D.C., 77 (1961) 57. 15. Jones and Seddon, Text. Research J., 34 (1964) 373; 35

16. Green, Jones, Syz and Zollinger, Helv. Chim. Acta, 48

23.

( 1965) 334.

(1965) 386. 17. Jones and Kraska, J.S.D.C., 82 (1966) 333. 18. McDowell, Lecture I.F.A.T.C.C. Symposium, Munich

1972; Melliand Textilber., 53 (1972) 1265. 19. Hoffmann, McDowell and Weingarten, J.S.D.C., 85 (1969)

306. 20. McGregor and Peters, ibid., 81 (1965) 393. 21. Bird, Manchester and Scott, ibid., 72 (1956) 49. 22. McCregor, Peters and Ramachandran, ibid., 84 (1968) 9.

Manufacturers' Publications and Pattern Cards The SoLiety does not dLLept any responcibllity tor the atatements in the tollowing notes. A n y publiLation abstrnLted may be reterred to b y members of the Society on dpplicatron to Dr C. 6. Steven\, Depdrtment of Colour Chemistry a n d Dyeing, Leeds Universily.

Badische Anilin- & Soda-fabrik A. G.

CELLlTON DYES POLANIL DYES AND PERLITON DYES ON CELLULOSE A C E TATE AND SYNTHETIC FlBRES ( M K 236C) SUPPLEMENT NO. 1 Sheets have been issued illustrating the follow- ing dyes on acetate, triacetate, polyester, nylon 6 and 6.6, and polyacrylonitrile fibre: Palanil Brilliant Yellow FFL; Yellow 5RX; Red I'RL; Brilliant Red GEL; Blue RTL; Dark Blue 3RT. Celliton Brown GFG; Navy Blue GFR; Grey GFBN; Black B; Black GFN. It is noted that all the Periiton dyes are now supplied under the name CeUiton or Palanil, including Perliton Brown H which had no Celliton equivalent.

COLORTHEK 111: TEXT AND PATTERNS This is the third volume in the Colorthek series of c d o u r atlases and is entitled Standard Shades on Cellulosic Fibres and their Blends with Synthetic Fibres - Colorthek Ill. The pattern card contains 2580 colours, from yel- low to black, reproduced on cotton with Indanthren vat dyes. The text volume contains recipes for reproducing each of these colours on a preset causticised 67:33 polyester-cotton blend cloth by batchwise exhaustion dyeing, firstly using the Cottestren dyes (mixtures of vat and disperse dyes) dyed at 125OC, and secondly using the Cottestren S dyes dyed at 130°C. The higher dyeing temperature used with the latter is neceswary because of the lower rate of diffusion of the disperse dye compo- nents. With both classes of dye it is considered that any differences in the colours obtained o n polyester-spun viscose rayon blends are so slight that they can easily be corrected. The recipes can also be used as a guide for formu- lating pad-liquors for pad-fixation application.

COTTESTREN M DYES This range of six disperse dye-vat dye mixtures is intended for dyeing 50:50 polyester fibre- cellulosic fibre blends either by batchwise HT dyeing or pad-fixation methods. Their appli- cation behaviour and fastness characteristics are equivalent t o those of the Cottestren S dyes.

Farbenfabriken Bayer

PHTHALOGEN W DYESTUFFS These dyes, which are a further development of the Phthalogen M range of ingrain dyes, are described in supplements to pattern card Sp.

367e. They contain solubilisers which enable them t o he incorporated in aqueous printing pastes without the need t o use volatile solvents. In other respects they are identical with the existing Phthalogen dyes, being mixtures of phthalocyanine precursors and organo-metal derivatives (nickel or copper) which react with- in the fibre t o give phthalocyanine pigments. In use they are dissolved in aqueous ammonia solution and thickener is then added. In certain cases Levasol PO and W S are also added. The prints should be dried rapidly and evenly and reaction and fixation are brought about either by neutral steaming (5-10 min at 100°C or 1-2 min at 17O-16O0C) or in hot air or by contact heat. Acidification, rinsing, soaping and rinsing follow. With the copper phthalocyanines residual ionic copper compound must be elimi- nated to prevent subsequent damage t o the fibre. The range comprises Phthalogen Brilliant Blue W-IF3GM, Turquoise W-IFBM, Brown W-3238, Navy Blue W-IRRM and Blue Black W-IVM. The prints have exceptionally high fastness t o light (1/1 depth 7-8 t o 8) , washing ( I S 0 4, 5), soda boiling and perspiration. Special applications include printing polyester fibre-cellulosic fibre blend cloths in combi- nation with Resolin disperse dyes, fixation being in hot air or by contact heat; and on naphtolated grounds in conjunction with Fast Salts for Africa prints. They can also be applied alongside reactive dyes.

L. B. Hdliday & Co. Ltd

SUBLA-PRINT COLOURS AS TRANSFER PRINTS ON POLYESTER, POLYAMIDE, ACRYLIC, DIACETATE AND TRIACETATE FIBRES This card describes 24 disperse dyes for heat- transfer printing. They are shown transferred from flexographic prints on paper produced from a water-based ink (10 parts dye/100 parts ink). The transfer conditions were: polyester 2 1 0 " ~ for 20 s; nylon 2 0 0 ~ ~ for 20 s ; acrylic fibre 195OC for 25 s; acetate 185OC for 20 s ; and triacetate l95'C for 20 s; a transfer print machine (Hunt & Moscrop) was used. A rating for the relative rate of dye transfer is given for each dye using the scale A (rapid), B (normal), C (slower than normal), and D (slow). The rating for any dye is the same on all fibres, since it is a characteristic of the dye, hut the actual build-up depends on the fibre, the depth on acrylic fibres being considerably lower than

on, e.g,, nylon. The influence of fibre type on wet fastness (washing and perspiration) is clearly shown, the ratings o n polyester being significantly higher than on nylon. The colours range from brilliant yellow t o bright bluish green.

Imperial Chemical Industries Ltd

TECHNICAL INFORMATION: D SERIES

D l 1 8 8 (Textile Printing). Procion Dyes: Print- ing on Wool by the Cold Print-Batch Process - International Wool Secretariat (L W.S.) Method - This process enables bright, deep prints of very good fastness t o be obtained on wool cloth without chlorinating the material before print- ing and without steaming to fix the prints. The procedure is t o print with a paste containing urea (300/1000) and sodium metabisulphite (20/1000) to accelerate dye absorption and fixation, t o batch cold for a minimum of 8 h and then t o rinse, firstly in water, then in dilute ammonia and finally in very dilute acetic acid. The highly reactive Procion M X dyes are particularly suitable; Rocion Turquoise P-A is recommended for very bright greenish blues.

0 1 2 4 7 (Paper). Proxel MB - The properties and use of this biocide, based on methylene bisthiocyanate, for controlling slime-forming organisms in papermaking are described.

0 1 2 6 3 (Cellulose Dyeing). Procion MX, H and H-E Dyes for Cotton Dyeing - Replaces D853. Detailed recommendations are given for dyeing cotton yarn, narrow fabrics and loose cotton with Procion MX, H, and H-E dyes by b a t c h wis e e x h a u s t i o n dyeing methods. Although the dyeing conditions differ, since the colours obtainable and the fastness character- istics of the dyeings are very similar, choice of dye often depends more on the properties of the individual dyes than on the group t o which they belong. Among the dyes listed is Rocion Green H-E4BD, an addition t o the H-E range, which is particularly economical, alone and in combination with the compatible Yellow H-E4R and Red H-E3B for producing dark greens, browns and similar deep colours.

0 1 2 9 1 (Textile Processing). Cirrasol LN-GS - This is a heat-stable lubricant, based on tridecyl stearate, for application t o continuous- flament synthetic-polymer fibre yarns before,

JSDC May 1973 185