Fundamental processes of dye chemistry. 1949

412 DETERMINATION OF LIGHT FASTNESS

and so the fastness ratings with different textiles were not comparable. This defect was especially troublesome with the artificial silks, particularly the mixed-fiberfabrics. From the fastness tables put out by the dye manufacturers, it was quite impossible for the dyers to select dyes of equal light fastness for use with mixed-fiber fabrics. Some remedy had to be worked out.

The I.G. Farbenindustrie worked for many years in an attempt to develop better standards for the different textile fibers, but these efforts did not achieve the desired improved standardization. During the course of this work, however, it became increasingly evident that other factors, in addition to exposure to light, had a significant effect on dye bleaching. Among these other factors were temperature, light intensity, and especially humidity and nature of the substrate. Thus, the fading of dyes on cotton and artificial silks was greatly affected by humidity, being much more rapid in moist air than in a dry atmosphere.'Wool dyes, on the other hand, showed a much smaller dependence on humidity, as shown by extensive tests in which cotton and wool dyes were given identical exposures under the varying climatic conditions prevailing in some eighteen locations around the world.

These data led to the evolution of eight new dyeing standards for wool. Attempts were made to circumvent the troubles due to variations In tint and to limit the standards to a single constant tint. Gray would have been the best color to use for this purpose, because it would be the easiest to compare with all the different colors. Unfortunately, however, there were not enough gray dyes available for the purpose. The situation was much better with blue dyes, and it was possible, by careful selection of dyes and depths of coloring, to arrive at a set of eight standards making up an approximately geometric series with respect to light fastness. Within this series, then, each step requires about twice the exposure of the preceding step to produce the same degree of fading. It must be emphasized that the light fastness ratings 1 to 8 do not give a direct measure of the actual fastnesses. An idea of the magnitude of this progression is best afforded by a practical example. If Standard 1 shows definite fading after 2 days' exposure, the other standards will require approximately the following exposure times:

Standard	1	2	3	4	56	7	8
Exposure, days		2	4	8	16 32	64 128 256

Since these values vary, depending on the brightness of the daylight and the hours of sunshine, they must be regarded as approximate, average values.

DETERMINATION OF LIGHT FASTNESS

413

The figures given above show clearly that groups 1 to 3 correspond to a very low light fastness, group 4 to medium, and group 5 to higher fastness. The groups from 6 on withstand rapidly increasing exposure times, and group 8 can be regarded as being outstandingly fast. These dyes in group 8 fulfill the very highest requirements, particularly since most textile fibers themselves are badly damaged or even completely destroyed on such long exposures. The light fastness ratings from 1 to 4 are given in whole numbers and those above 4 are expressed, if necessary, in half steps.

These new standards were accepted by the German Echtheitskommission and were published for the first time in the 6th edition of Verfahren, Normen und Typen.* In the meantime, the series has been still further improved, and in the 8th edition, the present official standards were set up as follows:

Fastness rating 1	0.8% Brilliant wool blue FFR extra
2	. 1.0% Brilliant wool blue FFB
3	1.2% Brilliant indocyanine 6B
4	1.2%	Supramine blue EG
5	1.0%	CyananthrolRX
6	3.0% Alizarin direct blue 3 GL
7	3.0% Indigosol 06 B
8	3.0% Indigosol blueAGG

Although the dyeing procedure was accurately described, it was still difficult for the outsider to dye up his own set of these blue standards. Hence, in order to eliminate all sources of error, the standards have been supplied free of charge by the German Echtheitkommission and by German and Swiss dye manufacturers.

The introduction of these standards simplified matters a great deal. By their use, it became possible to compare dyes of any depth or tint and, of special importance, on all the various fibers. Thus, this set of blue standards has become an absolute standard for the determination of light fastness and it has become possible to assign a numerical value for light fastness to every dye used in practice.

The actual determination of light fastness is very simple. The dyed material to be tested and the blue standard are half covered with cardboard and exposed together to daylight. The samples are exposed at least 2 cm. behind ultraviolet-transmitting glass in well-ventilated frames set at a 45-degree angle facing the south. When a distinct fading is ob-

* Verfahren, Typen, und Normen fur die Prufung und Beurteilung der Echtheitseigenschaften, Verlag Chemie, Berlin, 1939. This also gives the procedures

for determining other fastness ratings, such as fastness to washing, chlorine, alkali, and acid.

414 DETERMINATION OF LIGHT FASTNESS

served in the test sample, a narrow strip of the exposed portion of the sample and of the standard is covered with cardboard, and exposure is continued until a definite change is again observed. A second strip is then covered and the exposure continued. The method must be changed somewhat if several dyed samples, differing in light fastness, are to be compared with the blue standards. In this case, exposure is continued, without regard for the fading of the samples being tested, until standard 4 shows a definite fading. Then a strip of the standards and test samples is covered, and exposure continued until standard 6 is observed to fade. A second strip is then covered, and exposure continued until standard 7 shows a distinct change. In this way, three fading strips are formed across the standards and the test samples. The fastness of a sample is then easily determined by locating the standard corresponding in degree of fading, and the fastness rating is then the number of the corresponding standard. The ratings can also be expressed in words as follows: 1,small; 3, moderate; 5, good; 6, very good; 7, excellent; 8,outstanding.

A simple and usable method has thus been found for determining the light fastness of dyed materials. There was still a need for a standard method for the evaluation of dyes. As is well known, a dye fades more rapidly in light tints than in the deeper tints, and different fastness ratings are obtained for one and the same dye depending on the depth of tint.

As a first step, it was necessary to establish exactly the depth of tint upon which the fastness of a dye was to be based. To this end, so-called auxiliary standards were set up, these being standardized dyeings, of equal depth of tint, in the most important colors: yellow, orange, red, violet, blue, green, brown, and gray. Marine blue and black were exceptions, these colors being based on more saturated shades corresponding to their use in practice.

A second important point involves a consideration of the textile fiber used. A direct dye on cotton, for example, exhibits a different degree of light fastness from the same dye on glossy viscose or on matte artificial silk. Still greater differences are found between weighted and unweighted silks, the former giving a lower degree of light fastness. It was necessary, therefore, to set up auxiliary standards using the more important fibers such as cotton, artificial silk, acetate silk, weighted natural silk, unweighted natural silk, and wool. These auxiliary standards can be ordered from the German or Swiss Echtheitkommission or from dyemanufacturers.

These auxiliarystandards are consistent in depth of tint for all colors

DETERMINATION OF LIGHT FASTNESS

415

and all fibers, and hence the light fastness ratings for all dyes on all the fibers can be compared directly.

Marine blue and black are handled separately as already pointed out. Because they use a different strength for the auxiliary standards, marine blues can be compared directly only with themselves, and a black with blacks.

Fig. 57. Step exposure.

This is still not the complete picture. It is desired to give the dyers information about the fastness properties of light and dark tints, as well as of the middle tones. To this end, it was arranged that dyes should be evaluated in three depths of tint, having the relationship to the auxiliary standard of 1/3, 1, and 2. That is to say, the light tints were prepared using one-third, and the dark tints with twice, the amount of dye required to produce the depth of tint in the standard. In special cases, deviations from this rule were necessary, as with light rose or gray tones where one-sixth or one-ninth tints may be evaluated, or with saturated browns where fouror sixfold depths of tint may be used. The ratios usetd must always be specified. With marine blues, a double tint, and with black, a deep black, are measured.

Because of the varying strengths of dyes, these one-third and double tints are not of equal depth and hence are not comparable with each

other. Comparable fastness ratings are usually signified by printing in bold face type.

This new method is the basis for determining the light fastness ratings by German and Swiss manufacturers. Tables are given, listing three ratings for all dyes on all the textile fibers with which they are used.

This system for evaluating dyes meets all the requirements of the dyeing trade. Each dyer is now able to select, from the tables, dyes which will be equal in light fastness for use with mixed fibers, and at the safne time, have information about their behavior in light and dark tints.

Similar efforts are being made in England and America. Indepen-

418	TABLE I.

Chlorine

	SO3H	Cl		* Cl	Cl
		0		Reduction f ^Cl	XX
		C1			iCl
			*		9
		Cl			NH2
		Cl			*l
					Cl
		f^lC1		f^Sci	f^NH,
		O2Nfk^J		0.2N^^>	JNOZ
OH	«C1
•O"	-0°	H2N			^lN02
SO;JH	S03H
u
«OH
S03H					2-Hydroxy-3-naphthoic acid

Cl

Compound		Principal	Ifae
1.	6-Chloro-2-aminophenol-4-sulfonic acid	Azo dyes (chrome)
2. 3,4-Dichloroaniline-6-sulfonic acid		Azo dyes	(lake)
	(No. 12, Table IV)
3.	2,4,5-Trichloroaniline	Azo dyes	(lake)
4.	4,5-Dichlojro-2-aminophenol	Azo dyes (chrome)
5. 4,5-Dichloro-2-anisidine		Azo dyes
6.	6-Chloro-4-aminoresorcinol dimethyl ether	Azo dyes
7.	Naphthol AS ITR	Azo dyes (ice colors)
8. p-Phenylenediamine (paramine brown)		Oxidation brown, fur
	(No. 1, Table IV, and No. 5, Table VII)	dyeing, nitro dyes
9. 3,4-Dichloro-6-nitroaniline (No. 7, Table IV)		Azo dyes (lake)
10. 4-Chloro-2-nitroaniline (fast red 3 GL base)		Azo dyes (lake, ice colors)
11. Lithol fast yellow GG		Pigment
12. p-Dichlorobenzene		Moth repellent

Derivatives of o- and p-Dichlorobenzene

419

O

Cl

		Nitration
^er	C1	„/
'°'	O
	SO3H	See Table III
	See Table II

p. 109

H03S

Cl

Compound

13.4,6-Dichloro-2-aminophenol (No. 23, Table VIII)

14.4-Chloro-2-aminophenol

15.4 Chloro-2-aminophenol-6-sulfonic acid

16.4-Chloro-2-aminophenol-5-sulfonic acid

17.6-Nitro-4-chloro-2-aminophenol

18.4-Chloro-2-anisidine (chloranisidine P, fast red R base)

19.Dichlorodianisidine

20.2,5-Dichloro-p-phenylenediamine

21.6-Nitro-4-chloro-3-anisidine

22.2,5-Diamino-4-chloroanisole

23.2,5-Dichloroaniline (fast scarlet GG base)

24.2,5-Dichloroaniline-4-sulfonic acid

p. 90

\c,

O

NO2

See Table IV

NH2

Principal t/se

Azo dyes (chrome)

Azo dyes (chrome)

Azo dyes (chrome)

Azo dyes (chrome)

Azo dyes (chrome)

Azo dyes (lake, ice colors)

Disazo dyes

Fur dyeing

Azo dyes

Fur dyeing

Azo dyes

Azo dyes, pvrazolone dyes

420	TABLE II.	Derivatives of Chlorobenzene-p-sulfonic Acid	421

ci

Compound

1.o-Chlorometanilic acid

2.o-Aminophenol-p-sulfonic acid

3.o-Anisidine-p-sulfonic acid (No. 9, Table III)

4.o-Aminodiphenylether-p-sulfonic acid

5.Aniline-2,5-disi,ilfonic acid

6.o-Nitroaniline-p-sulfonic acid

7.2,6-Diaminophenol-4-sulfonic acid (No. 12, Table VIII)

Principal Use

Azo dyes

Azo dyes (chrome) Azo dyes (lake) Azo dyes (lake)

Azo dyes (esp. polyazo) Azo dyes (lake)

Azo dyes (chrome)

Compound

8. 6-Nitro-2-aminophenol-4-sulfonic acid (nitro acid I) (No. 11, Table VIII)

9.2,6-Dinitroaniline-4-sulfonic acid

10.2,6-Dinitroaniline

11.2,6-Dinitrodiphenylamine-4,3/-disulfonic acid

12.Tetrazo compound of No. 7

SO3H

Principal Use

Azo dyes (chrome)

Azo dyes

Azo dyes (lake) Triphenylmethanes Azo dyes (chrome)

»' ? ^ 2 O* O* ft.

3

Ss-iig's: ~? «

££.5"~3' g f"^;

s*Zs.i. o^s .

2.**| Ill

i^ - ZP

I <c

< 5

ill811111

8 -

»-• t— H- t-i »-> l-« h-i »->•-• O po t~4 p> en *» w to H-o o

oo>wo o o i

s*

^5

I g.

e

ft

'

o

o

3

O

o

5

cr n

424	TABLE IV.	Derivatives of p-Nitrochlorobenzene	425

Compound

1. p-Phenylenediamine (paramine brown) (No. 8, Table I, and No. 5, Table VII)

2.Chloro-p-phenylenediamine (No. 9, Table VI)

3.p-Aminophenyloxamic acid

4. p-Nitroaniline (fast red GG base) (No. 4, Table VII)

5.2-Chloro4-nitroaniline

6.2,6-Dichloro-4-nitroaniline

7.3,4-Dichloro-6-nitroaniline (No. 9, Table I)

8.4-Nitro-6-chloro-2-aminophenol

9.2-Chloro-4-anisidine (fast red R base)

10.5-Nitro-2-chloro-4-anisidine

11.3,4-Dichloroaniline

12.3,4-Dichloroaniline-6-sulfonic acid (No. 2, Table I)

13.4-Anisidine-3-sulfonic acid

14.p-Anisidine

15.3-Nitro-4-anisidine (fast Bordeaux GP base)

16.4-Anisidine-2-sulfonic acid

17.4-Aminodiphenylether-3-sulfonic acid

18.4-Acetamino-2-aminophenol-6-sulfonic acid

Principal Use

Oxidation brown, fur dyeing, nitro dyes, sulfur dyes

Fur dyeing

Azo dyes (subst. polyazo) Azodyes

Azo dyes (lake) Azo dyes

Azo dyes (lake) Azo dyes (chrome)

Azo dyes (ice colors) Azo dyes (lake) Azo dyes (lake)

Azo dyes (lake) Azo dyes (lake) Azo dyes

Azo dyes (ice colors) Azo dyes

Azo dyes

Azo dyes (chrome)

Compound

19.p-Aminophenol (No. 22, Table VIII)

20.6-Nitro-4-acetamino-2-aminophenol

21.p-Nitrophenol (No. 15, Table VIII)

22.4-Acetamino-2-aminophenol (No. 14, Table V)

23.Monomethyl-p-aminophenol

24.p-Aminophenol-o-sulfonic acid

25.4-Nitro-2-aminophenol-6-sulfonic acid (nitro acid III)

26.p-Nitroaniline-o-sulfonic acid

27.p-Phenylenediaminesulfonic acid

28.Benzoyl-p-phenylenediaminesulfonic acid

29.4-Chloroaniline-2-sulfonic acid

30.4-Chloroaniline-3-sulfonic acid

31.p-Chloroaniline

32.4-Aminodiphenylamine-2-sulfonic acid

33.4,4'-Diaminodiphenylurea-3,3'-disulfonic acid

34.Nitrophenylenediamine (No. 6, Table VII)

35.4-Aminodiphenylether-2-sulfonic acid

HNOs +

H2S04

,N02

S03H

Principal Use

Sulfur dyes, photography (developer) Azodyes (chrome)

Sulfur dyes

Azo dyes (chrome) Photography (developer) Azo dyes (as tosyl ester) Azodyes (chrome) Azodyes (lake)

Nitro dyes (amido yellow) Azo dyes (lake)

Azodyes

Azo dyes, pyrazolone dyes Azo dyes

Azo dyes, nitro dyes (amido yellow), azines (wool fast blue)

Azo dyes

Oxidation brown, fur dyeing Azo dyes

426

TABLE V.

Derivatives of 2,4-Dinitrochlorobenzene

427

OCH3 j^SNH2 j^NN02

^NO2 fnd\

£/

\Nitration

HO3S

NH2

HO3S

NH2

N02

Sj^SYXS>

OH

Compound

1.Chloro-m-phenylenediamine

2.Chloro-m-phenylenediaminesulfonic acid

3.6-Chloro-3-nitroaniline

4.4-Nitro-2-anisidine (fast scarlet R base) (No. 5, Table III)

5.2,4-Diaminoanisole

6.2,4-Dinitroaniline

7.p-Aminoazimide of J acid

8.m-Phenylenediaminesulfonic acid

9.2,4-Dinitrochlorobenzene

10.Hexanitrodiphenylamine

Principal Use

Azo dyes (end comp.) Azo dyes (end comp.) Azo dyes

Azo dyes (ice colors) Azo dyes, fur dyeing

Azo dyes	lake)
Azo dyes	subst)
Azo dyes	end comp.)
Nitro dyes	(amido yellow),

sulfur dyes Explosive

Cl

p. 62

NO2

NO2

N02

Compound		Principal Use
11.	2,4-Dinitro-4'-hydroxydiphenylamine	Sulfur dyes
12.	4,6-Diacetamino-2-aminophenol	Azo dyes (chrome)
13.	2,4-Diaminophenol	Photography (developer)
14.	4-Acetamino-2-aminophenol (No. 22,	Azo dyes (chrome)
	Table IV)	Azo dyes (chrome)
15.	4-Nitro-2-aminophenol
16.	2,4-Dinitrophenol	Sulfur dyes
17. Picric acid (No. 8, Table VIII)		Nitro dyes, explosive
18. Picramic acid (No. 9, Table VIII)		Azo dyes (chrome)
19. 4-Nitro-6-acetamino-2-aminophenol		Azo dyes (chrome)
20. 4-Nitro-6-chloro-2-aminophenol		Azo dyes (chrome)

428

TABLE VI.

Derivatives of Nitrobenzene

429

Compound

1.m-Phenylenediamine

2.Diphenyl-m-phenylenediamine

3.m-Nitroaniline (fast orange R base)

4.m-Aminophenylglycine

5.3-Chloro-6-nitroaniline-4-sulfonic acid

6.3-Chloro-6-nitroaniline (same as No. 14)

7.3-Chloroaniline-4-sulfonic acid

8.4-Nitro-3-chloroaniline

9.Chloro-p-phenylenediamine (No. 2, Table IV)

10.m-Chloroaniline (fast orange GC base)

11.3-Chlofoaniline-6-sulfonic acid

12.2-Chloro-4-dimethylaminobenzaldehyde

13.4,6-DianiIinometanilic acid

p. 75

Acid redn.

NO2

NH

Alkal. redn.

OS03H P. 123 [«

NHCOCOOH

NH2

NO

Principal Use	Compound
Azo dyes, acridines, azines	14. Same as No. 6
Azines	15. 2,4-Dichloroaniline (No. 7, Table VII)
Azo dyes	16. m-Aminophenol
Azo dyes (end comp.)	17. Metanilic acid (No. 5, Table VIII)
Azo dyes (lake)	18. Dialkylmetanilic acid (No. 30, Table VII)
Azo dyes (lake)	19. Dialkyl-m-aminophenol(No. 31, Table VII)
Azo dyes	20.	Nitrosodialkyl-m-aminophenol
Azo dyes	21.	Benzidine-2,2'-disulfonic acid
Fur dyeing	22.	Benzidine
Azo dyes, vat dyes	23.	Benzidine-3-sulfonic acid
Azo dyes (lake)	24.	Benzidine-3,3'-disulfonic acid
Triphenylmethanes	25.	Benzidineoxamic acid
Azines

Principal Use

Azo dyes

Oxidation dyes, azo dyes, fur dyeing Azo dyes

Azo dyes (end comp.) Rhodamines

Oxazines

Disazo dyes (acid and mordant) Disazo dyes (subst.), sulfur dyes Disazo dyes (subst.)

Disazo dyes (subst.) Polyazo dyes (subst.)

	o- £
toto	c/5 K> >.|o to jx tj tj -a >. o
as "as	« O 2.J**1 f^ 5' » ''O Z >* S Z
23	fH'SS'S.f'fls!
	>rftl II
s g	a - a^ssx - tsr» s ») »
II	fllp£|?l|?
t	i?'g9i^?ftii
£.	•• g. ^ g -

I 2

e ?' i»

fw «

OH-p<r>c»--ia&OT*.

If fl

61	»* =r2
	4 I
If	K
1:1	I	II
«

3

H

Z( « \Z ,

A-/?

I

Sapon. /-\^

OI—oO|

/^

o O

PVl/l

a o

QOil.

H2SO4

a o

Acetoacetic

1*	ester
	p. 129

Redn.

z-

Redn.	/	\
Z •	Z(	V-Z— O—
a	pV_/		a *

Hf

l-a xT

!-sr 1

! 8 S'O "5

r? I" ' C3

^ iff s s-ll

2

Sapon.

£L°3^\z

P.1S1\I/B

Z < - * T ) Z -*

Z

PVl/K P. 132 P

Acetic anhydride ^ / \

01

I" -^a^~

a

432

TABLE Vllb.

Derivatives of Aniline (continued from Table Vila)

433

NH2

NH2

Compound

25.Phenylglycine

26.Acetoacetanilide

27.p-Nitrosodimethylaniline

28.p-Aminodimethylaniline

29.p-Aminodimethylanilinemercaptan

30.Dimethylmetanilic acid (No. 18, Table VI)

31.Dimethyl-m-aminophenol (No. 19, Table 6)

32.Monomethylaniline ]

33.Dimethylaniline j

34.p-Dimethylaminobenzaldehyde

35.4,4'-Tetramethyldiaminophenylmethane (methane base)

36.4,4'-Tetramethyldiaminobenzhydrol (Michler hydrol)

37.4,4'-Tetramethyldiaminobenzophenone (Michler ketone)

38.Diethylaniline ]

39.Monoethylaniline J

40.Monoethyl-p-phenylenediamine

	N(CH8)2
	Principal Use	Compound
	Indigo	41. Benzylaniline (No. 11, Table IX)
	Azo dyes (lake)	42.	Ethylbenzylaniline
	Oxazines, azines, thiazines	43.	Ethylbenzylanilinesulfonic acid
	Thiazines, indophenob	44.	Dibenzylaniline
	Sulfur dyes	45.	Ethylhydroxyethylaniline
	Azo dyes	46.	Hydroxyethylaniline
	Rhodamines	47.	Dihydroxyethylaniline
f Diand triphenylmethanes, azines, oxazines,		48.	Diphenylaminemonosulfonic acid
L	thiazines, sulfur dyes, acridine dyes, azo dyes	49.	Diphenylamine
	Triphenylmethanes	50. p-Aminodiphenylamine (diphenyl black base,
	Auramine	51.	variamine blue RT base)
	Triphenylmethanes		Quinone
	Triphenylmethanes	52. Hydroquinone
f Diand triphenylmethanes, azines, oxazines,		53.	Aminohydroquinonedimethyl ether
1	thiazines, sulfur dyes, azodyes	54.	5-Nitro-2-aminohydroquinonedimethyl ether
	Azo dyes	55.	5-Benzoylamino-2-aminohydroquinone dimethyl ether
			(fast blue RR base)

OCH3

OCH3

Principal Use

Triphenylmethanes, azo dyes Triphenylmethanes, azo dyes Triphenylmethanes, azo dyes, thiazines Triphenylmethanes, azo dyes

Azo dyes

Indigo, triphenylmethanes Azo dyes, triphenylmethanes Triphenylmethanes

Triphenylmethanes, azo dyes, sulfur dyes Oxidation black, azo dyes, sulfur dyes

Vat dyes (helindone)

Photography (developer) anthraquinone dyes Azo dyes

Azo dyes

Azo dyes (ice colors)