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Патент USA US2132866

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Oct. 11, 1938.
. v2,132,866
'Filed Maron 29, 1937
Emmen-mu; '
1 '
Y ~
Burt H. Carroll, Rochester, N. Y., assigner to East
man Kodak Company, Rochester, N. Y., a _cor
poration of New Jersey
’ y
Application March 29, 1931,' serial No. 133,583
12 Claims. (Cl.` 95-7)
This invention relates to .sensitizedfphoto-
for which the other dye does not sensitize; vfor
graphic emulsions- >and more particularly to
photographic emulsions, such as4 those of the
example, when the red sensitization produced by
dye A increases in the presence of dye B which
gelatino-silver-halide type, containing a mixture
5 or combination of two ormore sensitizmgma' terials, at, least one of whichcooperates with'at
least one other to alter the sensitivity of ' the
Aemulsion to a greater degreethan is possible
With any one of the sensitizing materials alone.
10 The sensitization produced by my combination is
always -greater, in some spectral region, than the
sum total of the sensitizations produced by the
separate sensitizing materials. The sensitizîng
materialsv of my combinations are substances
15 generally referred to as dyes and more partic-k
.ularly as dyes of the cyanine class. .
sensitizes only for the green. When two or more
dyes sensitize for approximately Athe same or- 5
kWidely overlapping spectral regions (as in anum- A
ber of the eases to be described in the instant
application), supersensitizotion oon Still bode
tested, because if supersensitization obtains in
Such cases the total optical sensitization pro- 10
duced by a Combination of two'- or more dyes Will
always'fbe greater, under favorable Conditions.
than that which can be produced 'by any dye of
the combination alone at any _Conoentration- '
The magnitude of the supersensitization depends 15
upon the relative and absolute concentrations of
It is known in the art of making photograhic 'the dyes in the emulsion and 0n the type of
emulsionsvthat certain dyes of the cyanine class y Y emulsion. By suitable choice of conditions su
alter the sensitivity of photographic emulsions of_ `persensitization can always be made Ato assume
20 the gelatino-silver-halide type, when _incorpo- Values Which are readily observablerated therein. The sensitizing effect produced ~
M_y application deals with emulsions contain
bythe dye does not increase vproportionally to
Ithe amount of dye, but passes through a, maxIimum as the concentration is increased. Within
. 25 the range of concentrations most usefulr in prac-_
tice, the sensitivity increases vmuch lmore slowly
than _the concentration of the dye. Likewise, the
ing supersensitizingmixtures or Combinations of
onevor more sensitlzing dyes of the 8-alkyloxa
cal‘lî’ooyalîliue salts# wherein, the 8-a1kyl group
cOntains at least tWo Carbon atoms With one or 25
more sensitizing dyes of the pseudoeyanine
group. Just v110W the dyes of my mixtures oo
combined eiïect'of'two or more dyes on an emul- ` operate to give a supersensitizing eiîect is not
sionv is rarely equivalent to'the sum of'their
' 30' separate emects; in general' >it is much 1ess.
known- I shall'refer to the mixtures as oom
binations, although I do not intend to `imply ao
Mostcommonly, the combined eñect vis no greater ‘ that the dyes are Chemically Combined
than 'the eiTect of a single one of the dyes emAn object of my invention, therefore. _is to
ployed- in aV concentration equal »to the»Á `sum of. provide photographie' 1 emulsi0ns~fContainin8 a`
the concentrations ’or al1 the dyes »in the com-35 bination. ~Very frequently, the combined effect
-of two dyes is less than that of one of them
' '
y ;
_ .
supersensitizins combination of cyanine dyes.
A further object is to provide a process for Seus- 35
itiZinE photographie emulsions With supersens
itizing combinationsof cyanine dyes and to pro
' I have' found with certain combinations of two
Vide a method of increasing the sensitivity of
K or more cyanine dyes, that thecombined sensi- photographie emulsions sensitized With cyanine
40 tizationï-is substantially- greater, in some spectral . dyes. A stili further object is to provide a photo- 40
region, than .that of anyone of the dyes in the
vgraphic element - comprising _a Support coated'
absence of the- A_other or others. I will call this
with such, Super-sensitized emulsions.
phenomenon supersensitiz'ation. In general, at
more speoiñoobleotswilkbeeome apparent here
least'l one dye of my combination may be said to
45 be supersensitiged -by the' other ‘or others. „ The
The dyes which I employ in my supersensitiz- 45
-- dye which- is supersensitized mayv be called the ing-'combinations are lsensitizers of photographic
basic sensitizer and the other dye the“ super- emulsions when used alone. While there is more
sensitizer. However, the eiïect may be mutualV than one manner of formulating and naming
andthe dyes indistinguishable from the stand‘ 50 point of which is supersensitized.
Supersensitization is a highly speciñc phe-v
nomenon and is found only in mixtures or com-
„ binations of dyes from certain speciiic groups.
Supersensitization can be most readily observed,
_55 when adye is supersensitized in aspectr'al region
the dyes which I employ in practicing my inven
tion, it is believed that the formulas, systems of 50'
numbering and names _used herein are in accord
ance with those used during the development of _
the cyanine dye art to its present stage. ’I'he
most probable formulas 'of representative dye
types are given below in order to clearly set 55
2 .
the nature?of the materials employed in
my supersensitiziîig mixtures. These formulas
l The benzothia-2’-cyanine dyesfwhich can beA
represented by the follewing general formula:
should not be construed as limiting my inven
tion except as indicatedin the appended claims.
Among the' B-alkyloxac'arbocyanines, useful in
practicing my inìention are the following:V
Y, The S-alkyloxacarbocyanines îrwhich can be
represented bythe following general formula:
' The oxazolo-2'-cyanine dyes,vî which can be rep
resented by the following general formula:
x. 'Y
In the above?. formular, A represents an'alkyl"
group of at least two carbon atoms, R and R’
represent alkyl groups and X represents an acid
radical.; I have found it convenient- to employ
Y.the carbocyanine dye-,iodides r(where X .repre
2oî sents iodine) in§practicing Amy invention.; VHow
Èever, other dye=salts, such as the chlorides, bro
mides, perchlorates, alkylsulfates or alkyl-p-tolu
enesulfonates canbe employed,V for example. I
haveA also found it advantageous to employ dyes
25 wherein A represents an alkyl groupv of from two
Yto four carbon atoms, such 4as ethyl,vr isobutyl,
ßl--hydroxyethyiï or allyl groups,'for example, in
practicing myf? invention.
More speciñcally, I
havefound dyes wherein Arrepresents ethyl ari-d
‘n R and R’ represent methyl to be especially use
` ful.A The nuclei of the dyes can carry sii-nple sub
i In all of the above formulas of pseudocyaniìie
dyes, R and R' represent alkyl groups and» X rep
resents an acid radical. 'I'he oxazolo-2’-cyanines
can be substituted in the â-position- with substit
uents, such as alkyl or aryl groups ofthe benzene 25
series, for example, phenyl. In practicing myän
Vention, I have found it convenient tc> employ the
pseudocyanine dye-iodides (wherein X repre
sents iodine). However, other pseudocyanine
salts can be` employed, suchf-for example as the 30
chlorides, bromides, perchlorates, alkylsulfates or
stituents which do not interfere with sensitizing alkyl-p-toluenesulfonates. Ijhave further found
properties, suchyas, for example, alkyl, chloro,v it advantageous‘eniployfy pseudocyanine dyes
alkoxy or amino groups. symmetrical and vun
wherein R îand R’ represent an alkyl» group of
35 symmetrical oxacarbocyanine Ídyes can be em-` , from one toïour carbon atoms. The dyes where
ployed in practicing my invention.
in R and R' represent ethyl are particularly use
The ß-alkyl'oxacarböcyanines can be'prepared' fulîn practicing myïinvention. The pseudocya
by reacting 1-methy1benzoxazole quaternary salts
nine dyes can be substituted in their nuclei 'with
with trialkylortho esters of monobasic carboxylic y simple substituents which do not interfere with
acids ofv three'?or. more carbon atoms, in the pres
sensitizing properties, suchëfor example as alkyl, 40
ence of an organic base, e. g. dry pyridine, as de- ' chloro,falkoxy, or amino groups.
' scribed in UëS. Patent No. 1,962,12‘lf.4 By em
ployingy mixtures ofsubstituted benzoxazole and
unsubstituted benzoxa-¿zole quaternary salts, mix
45 tures of symmetricaland unsymmetrical 8-a1kyl
oxacarbocyanine dyes can be obtained.
Among theîpseudocyanine dyes which canè'be
empigoyed in practicing my invention are the fol
'The 2„2'-cya'm1neV dyes, which can be: represent-î
ed by the following general formulaî
Brooker and Keyes, in the Journal of the Amer
ican Society, vol. 5T, pages 2488-2491 (1935) have
reviewed 4the literature pertaining to pseudocya
ninej dyes and describe methods for'the prepara
tion thereof.
Oxazolopseudocyanine dyes are deu
scribed in U. S. Patent No.;1,969,4fi6.á
1 f
The objects 'of my invention can be accom
plished by merely incorporating one-or more sen
sitizingI , 8-alkyloxacarbocyanine dyes together 50
with one or more sensitizing pseudocyanine dyes
capable of superseïnsitizing the B-alkyloxfcarbo
cyanine in a photographic emulsion. My inven
tion is particularly directed to the ordinarily em
pioyed gelatina-‘silver-halide emulsions. However,
The thia-2-'-cyanine dyes, which can be repre
sented by'the following general formula:
my supersensitizing combinations can Vbe ern-`
`ployed in emulsions in which the carrier is other
than gelatin, for example, a resinous substance
or cellulosic derivative which has substantially no l
deleterious eiïect on the light-sensitivematerials. 60
As silver halide emulsions, I >include such emul
sions as are commonlyV employed inthe art, for
example, ysilver chloride or silver bromide emul
sions which can contain other salts which may be
light-sensitive. By way of illustration,'-theherein 65
described.v supersensitized emulsions were prepared» employing an ordinary gelatina-silver-bro- -
mide- emulsionyof ordinary concentration` (ap
proximately 40g. of silver halide -per liter). ’I'he
dyes were generallyv employed iny concentrations
of the'order of liîi mg. per liter of ordinary emul
sion, but can be employed in concentrations sev
eral times greaterl or less than that. 'I'he ratio
of concentration of the 8-alkyl'oxacarbccyanine
dye to the concentration of the pseudocyanine dye 75
may be varied widely from 5:1 to 1:5, for exam
ple. The most favorable. conditions for supersen
carbocyanines with pseudocyanines likewise show `
supers'ensitizing effects; " Theiï 2,2’-‘dimethyl-8-
Y sitization of the desired magnitude must be de- -
ethyloxacarbocyanines 'are' of particular utility
termined by-experiment, the mannerof which will ' in »practicing my invention. Pseudocyanine dyes
>*be apparent to A'those skilled in the art »upona com
plete perusal of these specifications.`
The methods of incorporating dyes in- emul
containing the 5,6-benzothia- nucleus are usually
of lesser utility in- practicing'my invention.' 'I'he
' oxazolopseudocyanine dyes substituted in the 4
sions are simple'an'dwell known to those skilled ' position of the oxazole nucleus by analkyl group,
‘ vin the 'arti- In practicing my invention, the dyes i such as methyl, "or by an aryl group, such as
of 'my combinations can be added separately-or
together. It is convenient to add the` dyes sepa
- ‘rately 'in' the Vform of theirsolutions in appro
- priate solvents. @The solvent must, of course, be
phenyl, for example,vare- especially useful in prac-- 10
~`ticing my invention.
Among others, the following combinations have
been found'fto be `imrticularly useful:
' za'aimeoiyieethyiomearbócya?ine iodide with l indiaan-affini“ iòdiae.
compatible with the emulsion,.substantially- free
from any deleterious‘effect on‘the lightesensitive
materials and capable of dissolving theA dyes.
25 Methanol has proven satisfactory asa solvent for
In general, it can be said ofemy combinations .
that‘the oxacarbocyanine‘ is ythe d_ye‘supersensi
_tired (basic supersensitizer) and that the pseudo
cyanine is the supersensitizer.. However, the 25
.the dyes in practicing ‘my invention. The dyes f nature of this relationship between the dyes of my
-are advantageously incorporated in the ñnished, combinations is frequently dimcult to determinel
washed emulsion and should be uniformly dis
and is, in fact, immaterial to the practice of my,
tributed throughout the emulsion. The emulsion
30 can .then4 be converted into a photographic ele«
Still further examples showing the application 30
of my invention could be cited, but the foregoing
ment by coatingupon a support, such as glass,
cellulose acetate, cellulose nitrate or other cellu
will be suiiicient to teach those skilled in the art
lose derivative or resin in a-manner well known in - the manner in which my invention is carried out
The accompanying drawing is by Way of illus
tration and'. depicts the supersensitizing effect of
my new combinations.
The figure of the drawing
is a diagrammatic reproduction of three spectro-á
and the principles of sensitizing photographic
emulsions .with supersensitizing combinations,
such as described herein. While I have illustrated
only combinations containing- two dyes, my com
binations can as well contain one oxacarbocya
grams showing, first, the sensitivity of 'a silver , nine cooperating' with two or more pseudocya
40 bromide emulsion containing an _8-alky1oxacarbo
nine dyes. Likewise my combinations can con
Cyanine dye (represented by'the‘dot-and-dash
line), second, the sensitivity'of the same silver
bromide emulsion containing a pseudocyanine dye
tain one pseudocyanine dye cooperating withvtwo
or more oxacarbocyanine dyes.
Cyanine dyes containing hydroxyalkyl groups
(represented by the dotted line) ,' and third, the _ can be ~prepared from cyclammonium quaternary
45 sensitivity of the same emulsion containing a
mixture or combination of the said 8-alkyloxacar
bocyanine dye r`with the said pseudocyanine dye
(represented by the solid line). The supersen-.
sitizing effect is apparent from the drawing. f ‘
More speciñcally in the drawing, curve A repre
sents the sensitivity of an ordinary gelatino
methyl-ß-ethyloxacarbocyanine iodide in a con
, -centration of 10 mg. per liter of emulsion; curve
55 B represents the sensitivity of the same emulsion
containing 3,1'- diethyl-«i-phenyloxazolo-2’- cya
salts prepared by reacting heterocyclic nitrogen 45
bases with halohydrins, e. g. ethylene halohydrins
- and propylene halohydri'ns. _ It is advantageous to
employ the bromohydrins.
The heterocyclic
nitrogen base and the bromohydrin are merely
heated together for several hours, e. g. 25 to 30
hours or longer, at about 100° C., though 150° C. '
can be employed. 'An excess of the bromohydrin
is vadvantageously employed. Following the reac- -
tion, the solid reaction product is advantageously
converted to the iodide by treatment with p'otas- - 55
sium iodide. This can be accomplished by dis
nine iodide in a concentration of 10 mg. per liter solving the crude Quaternary bromide in hot
of emulsion, and curve C represents the same- water and treating the solution with a hot aque
emulsion containing 2,2’-dimethyl-B-ethyloxacar-`
ous solution of potassium iodide (1 g. per cc. of l
co bocyanine iodide and 3,1’-diethyl-4`-phenyloxa-- water). Cyanine dyes containing hydroxyalkyl
zolo-2'-cyanine iodide in concentrations of 10 groups are describedvin the> application of Leslie
mg. and 15 mg. per liter, respectively. The sensi .G. S.Í Brooker and Lloyd A. Smith, Serial No.
tivity of the emulsion represented by curve C, as 133,524, filed of even date herewith.
measured through a Minus Blue Wratten No. 12
What I claim and desire to be secured by Let
65 Filter, is about 40% greater than that of the ters Patent of the United States is: .
` ~
emulsion represented by curve A.
1. A photographic silver halide emulsion con
The spectrograms corresponding to the figures taining a supersensitizing combination of at least
of the accompanying drawing were made in a one sensitizing dye, selected from the group con
wedge spectrograph. ' The intensity of each hori
sisting of ß-alkyloxacarbocyanine dyes in which'
zontal line was approximately one-tenth that `at
the next lower line. Where the spectrograms were
compared as in the drawing, the exposures were
for ‘the same time and the test plates of each dye
the 8-alky1 group contains at least two carbon 70
atoms, with at least one sensitizing pseudocyanine
' >were developed together.
The other of my combinations of 8-alkyloxa
>2. A photographic gelatina-silver-halide emul
sion containing a supersensitizing combination
of at least one sensitizing dye selected from the 75
1 ' -aisance
8. A photographic gelatino-sllver-halide emul
group- consisting -of 8-alkyloxacarbocyaníne dyes
in which the 8-alkyl group contains at least two sion containing a supersensitizìng combination
carbon atoms, with at least one sensitizi'ng of at- least one 2,2’-dimethyl-8-ethyloxacarbopseudocyanine dye.
cyanine dye with at least one oxazolo-2’-cyanine
3.. A photographic gelatino-silver-halide emul
sion containing a supersensitizing combination vof
at least one sensitizing dye selected from‘the
sion containing a supersensitizing combination
of at least one 2,2'-dimethyl-ß-ethyloxacarbo
_ group consisting of 8-alkyloxacarbocyanine dyes
9. A photographic gelatina-silver-halide emul
in which the 8-alkyl group contains at least two
10 carbon atoms, with at least one sensitizing thia
2’-cyanine dye. -'
10. A photographic gelatino-silver-halide emul
sion containing a supersensitizing combination
4. A photographic Ígelatina-silver-halide em -sion containing- a supersensitizing combination ` of at least one 2,2’»dimethyl-8-'ethyloxacar
of at least one sensitizing dye selected from the
15 group consisting lof 8--alkyloxacarbocyanine dyes
s in which the 8-alkyl group contains atleast two `
s carbon atoms, with at least one sensitizing 2,2’
cyanine dye.
bocyaninehalide with at least one 1,1.’-diethyl
` 2,2'-cyanine halide.
11. A photographic gelatine-silver halide emul
sion containing a supersensitizing combination
of atleast one 2,2'-dimethyl-ß-ethyloxacarbo
" 5. A photographic gelatino-silver-halide emul
20 sion containing a supersensitizing combination of
, 12. A photographic gelatino-silver-halide emul
group consisting- of 8-alkyloxacarbocyanine dyes
sion containing a supersensitizing combination
of at least one _.sensitizing dye selected from
"the .group consisting of 8-a1kyloxacarbocyanine
in which‘the 8-alkyl group contains at least two
`carbon atoms, with at least one sensitizing
phenyloxazolo-2'v-cyanine halide.
at least one sensitizing dye -selected from the
oxazolo-2’-cyanine dye.~
dyes in which the 8-alkyl group containsy at least 25
‘6. A photographic gelatino-silver-halide emul
two carbon atoms, with at least one sensitizing
sion containing a supersensitizing combination
of at least one 2,2’-dimethylf8-ethyloxacarbo-cyanine dye with at least one thial2’
dye selected'from the group consisting of 2,2'
cyanine dyes, thia-2’-cya,nine dyes, Selena-2ï
‘cyanine dyes, 3,4-b'enzothia-2f-cyanine dyes _and
7. A photographic gelatine-silver-halide' emul
l vsion containing a supersensitizing combination
of at least one 2,2’-dimethyl-8-ethyloxacarbo
cyanine' dye with at least one 2,2’-cyanine »-dye._
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