Note: Descriptions are shown in the official language in which they were submitted.
1066939
This invention relates to an improved process ror
hardenlng photographic gelatine layers, in particular silver
halide emulsion layers which contaln gelatine a8 binder.
Photographic gelatlne emulsione irequently contain
hardeners which act over a prolonged period. The hardenlng
process in rreshly prepared emulsion layer~ may therefore
continue during storage of the layers until the emulsion
layers iinally lose their permeability to treatment baths.
This results in unde~lrable sensitometric eiiects, ior example
~evere reduction in contrast aiter storage.
It has long been known that certain hardeners harden
more rapidly ln a neutral or alkaline medium than an acid
medium. Conversely, the stabillty of photographic emulsions,
which nre oiten digested over a long period, is substantlally
higher in the acid region. The majority Or emulsions undergo
severe iogging in the alkaline region.
There has thereiore been no lack of attempts to ad~u~t
the cast emulsion layers to a higher pH ior only a short
tlme. Thus, ior example, U.S. Patent Speci~ication No. 3,
a55,ooo describes a proces~ in which the cast photographic
material 18 covered with an aqueous solution Or a volatile
organic ba~e which i8 left to dry partly and then removed.
Thls transient contaot o$ the emulsion layer with the
alkaline coating accelerates hardening during the normal
drying prooess even li the base is removed irom the emulsion
layer shortly aiter it has been applied. In practice, this
process has mumerous diriculties. In combination wlth rapid
casting machines the process can only be employed ii a sep-
arnte air ~upply i8 provided ior applying the ~mine solution~
This air supply must be carefully sealed ofi because oi the
A-G 1192 - 2 -
~066939
smell and the "threshold limit values" of such amine solutions. In addition,
the exhaust air must be washed in acid solutions to remove the amines. In
spite of all these precautions, the finished material still has an unpleasant
amine odour which is particularly pronounced when large format photographs
are being processed or when roll films are treated in so-called printers
which heat up in use.
It is an object of this invention to develop a process for harden-
ing photographic emulsion layers which reach the desired degree of hardening
shortly after they have been cast and in which the full action of the hardener
sets in at once instead of building up over a prolonged period. Another
object of the invention is the practical application of hardening accelerators
to photographic emulsions which already contain conventional hardeners.
Accordingly the present invention provides in a process for forming
a gelatine-containing multilayer photographic material containing 1, 3, 5-
triacryloyl-hexahydro-l, 3, 5-triazine (triacylic formal) as hardener the
improvement which comprises incorporating in a non-light sensitive layer
which is free from hardener a tertiary amine whose boiling point is above
200C and which is of the formula
Rl-N-R2
R3
which contains at least two hydroxyl groups and in which Rl represents CH3-
CHtH)~CH2; CH2tO~ CH-tOH)-; C~12(OH)-CH2-; H[o-cll2-cH(oH)-cH2]3 or 4; CH2(OIl)-
CH2-CH2-O-CH2-tOH)-CH2 or a cyclohexyl or phenyl group either of which is
unsubstituted or is substituted with a hydroxyl group and R2 and R3, which
have the same or different meanings represent CH2(OH)-CH2-, CH3-CH(OH)-CH2-;
CH2(OH)-CH(OH)-CH2-; H[0-CH2-CH(OH)-CH2]3 or 4 or a straight or branched
chain alkyl group containing from 1 to 4 carbon atoms.
~D _3_
:
~066~39 : :
Examples of suitable aklyl groups include CH3, C2H5, C3H7 and
i-C4Hg.
Typical examples of suitable tertiary amines of the above general
formula are summarised in the following Table. ;~
'
r~
-4-
1C~66939
,'
: :,
o~
N
O O O 0 4 0 0 0 0 0 0 0 0
O O ~ O O O t~ O O O ~ O 0~
5, 5 ~
t
. ~ :~N o
I~
y I I I I O O Y
P~ N ~ 1~ ~ X C~ æ
y ~ ~ ~ O 1~
t~ 1 N N ~ N ~ .:
N
U U U U U U U ~ U U U
, ',
_ '.
~ ~ I 1 1 3~
~ ~ ~ ~ ~ ~ O
N Y Y Y ~ I ~ æ Q ~ ~
æ ~ æ o~ Y q q q q æ
q q q ~, g 0~ 0~ ~ ~ q
~ ~ u~ ~ ~ ~ ~ ~ ~ u~
.:
,. q .,
_I aN ~N 3N l_
æ æ ~ g~ o æ æ Y q Y ~b
q u q ~ q q q o~ o æ q
UUUUUUUUUU~--
O _~ N tr~ 0 1~ X Cl) O _1 N
Z
5 -
` " ~L066~39
~ '
.r~
o o o o o o o
~ t, ~ ~, ~, ~,
. ,
.
~ .
:~
o,
~ ~:
.. ~
C~ ~ ~ 3~
o, o, ~
~N !r~
C~
. ... .
.' ~ 1
Y Y
Q. ~ :
..
I I ~ .
y~ .
c~:-' ~ Q ~ Y~ ' Q o, Q
,~ ~ ~
Q y y y
~, Q ~ ~, o o
~N ~ ~N ~1 ~N 3?'
Z ~ O t` X Cl~
-6- ~:
1066939
Preparation of the tertiary amines of the general formula
is carried out by reacting aqueous ammonia or amines with
epoxides. The reaction as such has been known for a long time.
Hydroxyethers are formed as by-products of the synthesis due
to the reaction of the hydroxyl groups originally formed with
the epoxides. Therefore, in order to avoid the formation
of secondary amines which occurs in a stoichiometric reaction
mixture and which causes fogging in the emulsions, the epoxide
is used in a 10 to 20 % excess for synthesising the compounds
according to the invention. This obviates time consuming
distillation. Since the small quantities of hydro~yethers then
formed cause no trouble, substantially no disadvantages are
iound in use. The compounds according to the invention are
viscous oils with boiling points above 200C.
Detailed descriptions of the preparation of the tertiary
amines according to the invention may be found, for example
in the article by E. Ulsperger and R. Dehus in Journ. f. prakt.
Chemie 4th Series, Volume 27 (1965) page 195 and in Am. Chem.
Soc. 52 (1930), 1530 and Journ. of org. Chem. 8 (1943), 191 and
in US Patent Specification No. 2,147,226.
The process according to the invention substantially avoids
the disadvantage~ which ari~e when hardeners are added to the
photographic emulsions and protective layers and which manifest
themselves in continuous lo~s of gradation and final density
during storage of the layers so that the final condition of
the emulsions is often reached only after several weeks and
in the fact that the water absorption is still so high after
several months, especially if the photographic materials are
processed at 35C, that the drying capacity is considerably
reduced, particularly in material processed for viewing by
reflected light. In addition,application of the process
A-G 1192 - 7 -
.. . .
1066939
~ccordlng to the lnvention obvlates the dlrrlcultle~ re-
sultlng rroD the low mechanical reslstance o~ photographic
layers which h~ve undergone severe swelling.
The tertiary amlnes u~ed according to the invention have
e~cellent co~pat~bility with gelatine and do not e~i'ect the
sensitivity o~ the emulsion layers with which they come ~to
contact nor do they a~i'ect the speed oi development or ability
to rl~ the layers. They have no deleterious a~rect on the
ei~icienoy oi the sen~itizers in colour photographic materlals
or on their distrib~tlon and absorption. They are highly
compatible with the additives normally used in photographic
materials The tertiary amines are ueed ln protective layers
which are free irom hardeners. In multilayered photographic
~aterials the tertiary amines may be used in one or more than
~5 one protective layer. Subsequent hardening of the protective
-- l~yers is effected eolely by the hardener which di~ruses
- irom the emulsion layer into the protective layer aiter casting.
; The tertiary amine~ are generally used in a quantity
Or iro~ 5 to 75~ by weight, based on the weight oi the binder
~,
ao ln the intermediate layer or protective layer, and prererably
ln a quantlty oi trom 10 to 20~ by welght. As already men-
tioned above, the tertiary amines have no deleterious ei'~ect on
photographlc processing oi the material~, nor do they cause
any trouble ln the baths into whlch they are lntroduced durlng
the processlng o~ the materials which have been treated
accordlng to the invention.
The layers o~ which the photographic materials descrlbed
here are composed lnclude all the type~ Or layers commonly
. .
A-G 1192 - 8 -
.
.
1066939
used in such materials, for example light sensitive silver
halide emulsion layers; protective layers; filter layers;
antihalation layers; back layers or photographic auxiliary
layers in general. Although the tertiary amines according to
the invention are not used in emulsion layers which contain
light sensitive silver halides but, as already mentioned above
in the photographic auxiliary layers which are in water
conductive contact with such emulsion layers, the tertiary
amines are completely inert towards photographically active
substances present in the light sensitive silver halide
emulsions, such as water-soluble and emulsified water-soluble
dye components, stabilizers and sensitizers. In addition, the
tertiary amines according to the invention can be combined
with all the compounds belonging to the classes o~ hardeners
hitherto known, ~or example formalin, mucochloric acid,
triacrylic ~ormal, bis-vinylsulphones, bis-vinylsulphonamide,
dialdehydes or bis-chloroacetamides. This combined use of
; hardeners is carried out according to the invention by adding
the known hardeners to the emulsion layers in the usual manner
and the tertiary amines to the intermediate or auxiliary
layers which are free ~rom hardener. ~n addition to gelatin,
the photographic auxiliary layers in which the tertiary
amines according to the invèntion are used may contain
water-soluble high polymer compounds, in particular poly-
vinyl alcohol, polyacrylic acid sodiu~ and other copolymers
which contain carboxyl groups, polyvinyl pyrrolidone, polyacryl-
amide or high molecular weight naturally occurring
substances such as dextranes, dextrines, starch ethers,
alginic acids or alginic acid derivatives, cellulose acetate,
cellulose sulphate.
A-G 1192 _ 9 _
.
10~6939
The hardening action Or the tertiary amines used
accordlng to the invention generally ~etg in ~o rapidly
that the degree Or hardening required for, rapid processing
at elevated temperatures i9 reacted after only about 3
day~s storage,
The activity of the hardening compounds is determined
by the melting point oi the layers which in turn can be
determined as follows:
The combinati~n of layers cast on a substrate is half dipped
in water which ix continuously heated to 100C. The temp-
erature at which the layer runs off the ~ub~trate (forma-
tion of streaks) is termed the melting point or melting off
point, By this method of measurement unhardened gelatine
layers never show an increase in melting point,
Determination oi the water absorption is carried out
AS follows:
The test sample i~ developed as a black sheet in ~ conventio-
nal colour developmentproces~ and i8 weighed after the final
bath and stripping off excess water. The sample is then
dried and weighed again. ~he difference divided by the
surface area of the test sample oonverted to m2 is the water
absorption per m .
Example: S~mple weighed wet= 60 g
" weighed dry = 55 g
5 g dif~erence
Size of sample = 200 om
Water ab~orption per m2 = 25 g.
The y-values which are used in the following Examples
as a further oriterlon for the activity o~ the tertiary amines
aocording $o the invention are determined in known manner.
A-G 1192 - 10 -
.
:. :
1066939
- r-Values: r2 at density 1.4 over rOg value for cyan and magenta and r2 ior yellow at density 1.0 over $og value.
By the proce~s according to the invention, complete
- hardening of the multilayered p~otographic ma~erials is
achieved to an opt~mum degree in a surprisingly short time.
This unexpected e$fect of the tertiary amines is particular-
ly important $or hardening photographic colour materials.
The desired degree o~ hardening can be adjusted in a well
controlled manner while the materials are being prepared
and there is no need for prolonged storage times with the
con~equent uncertainty of uncontrollable after-hardening.
The material iB ready $or use only 3 days after casting
~. .
~or processing photographic materials at elevated temper-
atures whioh make particularly ~tringent demands on the
hardening process. The multilayered materials hardened
15 by the pro¢ess according to the invention are distinguished
by a surprisingly low water absorption (tendency to swell)
which is particularly advantageous ~or processing at ele-
vated temperatures. ~his property goes hand in hand with
excellent stability of the gradation o$ materials which have
20 been hardened aocording to the invention. Another advan-
tage oi the process acoording to the inventio~ lies in the
possibnity o$ aohieving the desired oomplete hardening o$
the layer oombination and its water absorption with rela-
tively small quantities o$ hard~ner. This results in a
~urprising improvement in the r-stabilitY.
Example 1
A colour photographic material rOr viewing by refleoted
light w~ prepared by applying the ~ollowing layers succ-
essively to a paper substrate whioh has been backed with
polyethylene and oovered with a bonding layer, the emulsion
layers containing the usual additions of wetting agents,
A-G 1192
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1066939
~tabilizer~ etc.:
- 1. as bottom.layer a 4 ~ thick blue sensitive silver
bromide emul~ion layer containing, per kg of emulsion,
25.4 g oi silver (88~ AgBr, 12% AgCl), 80 g oi gelatine
and 34 g o~ the ~ollowing yellow component:
S03H NH-co-cl7H35
-NH-CO-CH2-CO-
OCH3
This layer ~ hardened with 60 ml per kg of emulsion
Or a 3% aqueou~ triacryloiormal solution (oondensation
product oi 3 mols oi iormaldehyde and 3 mol~ oi acrylo-
nitrile);
2. as lntermediate layer a 1 ~ thi¢k gelatine layer which
contai~ed20~ by weight oi oompound 1, ba~ed on the gela-
tine:
3. as middle layer a 4 ~ thiok greensensitive silver chloro
bromide emulsion layer which oontained,per kg oi emulsio~
22 g oi silver (77% AgCl, 23% AgBr),80 g oi gelatine
and 13 g oi the magenta component
C20H41-~-cO-NH-~ ~ o
3 ~ N
CH2
and which washardened with 50 ml oi triacrylo~ormal
(3%;~ per kg oi emul~ion;
A-G 1192 - 12 -
1066939
4. a 1 ~ thiok intermediate l~yer as indicated under 2;
5. as top lay,er, a 4 p thiok red ~en~tive ~ilver chloro-
bromide emul~ion layer which oontained,per kg of emulsion
23 g oi sil~er (80~ AgCl, 20~ AgBr), 80 g of gelatine
und 15.6 g of the following cyan component;
~ -NH-C0-C-0-
3 ~1 H3
which had been hardened in the ~ame way as the middle layer
(number 3).
6. A 1 p thick protective layer of the composition indi-
cated under 2 and 4.
Example 2
Example 1 wasmodified in that 30 ml of 3% tria¢rylo-
for~al ~olution per kg Or emulsionwere used for hardening
the bottom layer (number 1) and 25 ml oi 3% aqueous tri-
acryloior~al solution we~ u~ed ~or hardening the middle
laye~ (number 3) ~nd for hardening the top layer (number 5).
ExamPle 3
Example 1was modiiied in that the two lntermediate
layer~ 2 ~nd 4 ~nd the proteotive layer 6 ~re all hardened
in the same manner i.e. with 70 ml of a 3% aqueouæ trl-
aoryloiormal solution per 10 kg oi 5~ aqueous gelatine
solutlon but they did not contain any tertiary amines acc-
ording to the invention.
The properties oi' photographic materials hardened
according to Examples 1 to 3 are illustrated by the graphe.
Fig. 1 ~hows the change in melting point of the layers
during ~torage oi' the materlals; Fig. 2 ~hows the variation
in water absorption of the materials depending upon the
storage time;and Fig. 3 shows the effect of storage
A-G 1192 - 13 -
1~66939
on the gradatlon oi the materials.
As oan ~e ~een ~rom Fig. 1, the layers oi the colour
photographic materials prepared according to Examples 1 and
2 ior viewing by reilected light are iast to boiling aiter
only 7 days' storage and can be proce~sed at 35C a~ter
3 days. Layers of the ma~erial prepared according to
Example 3, which does not contain the compounds according
to the invention, acquire these properties only aiter 4
or 5 weeks. The time entered along the abscissa is in
days ~ all three graphs.
The variation in water absorption at 35C shown in Fig.
2 shows that materials prepared according to Examples 1 ~nd
2 using the oompounds according to the invention have an
optimum mol~ture absorption o~ 40 to 45 g/m2 arter 4 to 6
week~. The material according to Example 3 still ab~orbs
about 70 g oi water per m2 under the same conditions.
Although the water absorPtion oi this material could be
reduced by adding a larger quantity o~ conventional hardener~
this measure would also reduoe the stability oi the grad-
ation. In such cases, water absorptlon drops below 30 g/m2
aiter about 5 months and the gradation 1~ ~ar outside the
limits o~ toleranoe. When Fig. 2 i8 viewed in conJunction
with Fig 1 it can be seen that the materials according to
E~amples 1 and 2 iinally reach a water absorption of 30 to
40 g/m2 which remains constant aiter storage and complete
hardening, whereas in the material according to Example 3,
which has been hardened in the conventional manner, the
water absorption continues to decrease.
The variation in gradation depending upon the storage
time oi the hardened materials represented in Fig. 3clearly
shows the improved stability oi gradation of layers which have
been hardened by the prooess oi the invention in accordance
- A-G 1192 - 14 -
.~ ,
1066939
with Examples 1 and 2.
The dir~ering result~ obtained with the three emulsion
layers o~ the colour photographic material viewed by re~lec-
ted light have the following causes:
Layers which contain e~ulsi~ied colour couplers and parti-
cularly colour couplers of this kind which contain sulpho
groups are substantially more di~ficult to harden with
conventional hardeners than pure gelatine layersO A rela-
tively large quantity o~ hardener must be used to compensate
for this dlsadvantage. During hardening whioh proceeds
slowly, the hardener diriuses ~rom the layers which contain
the components into adJaoent protective layas where it
causes overhardening. Dif~usion of the processing baths
into the photographio material is deleteriously affe¢ted
by such overhardened proteotive layers so that ~ regression
occurs. Moreover, during slow hardening the har~ner is
liable to react with the coupler to a greater or less extent
depending on the chemioal constitution. This also causes
regression of the final density and r. When tertiary amines
acoording to the ~vention are used, these disadvantages are
obviated by the fact that no hardeners are added to the
proteotive layers wlth the oompounds aooording to the in-
vention. Arter oa~ting, the amine rapidly di~fuses into
the emulsion layers and, by virtue of its excellent buifering
oapacity, it ens~res rapid adjustment of pH to 7.8 to 8.5.
Hardenlng takes plaoe rapidly within a few days so that the
reaction between hardener and oomponent is to a large extent
prevented and, moreover, substantially le~s hardener, need
be u~ed, a faot which i8 an advantage for this purpose. The
3o protective layer~ are hardened only/the small quantity o~
hardener which diffuses ~rom the emulsion layer~ during the
short time o~ 3 to 7 days. The protective layers there~ore
A-G 1192 - 15 -
~ . . :
1061E~939
8till have sufiicient capacity to swell e~en when the mat-
erials have been completely hardened.
E~ample 4
Example lw~s modiiied in that the intermediate layers
Nos. 2 and 4 dil not contain any tertiary amines acoording
to the invention nor did they contain any conventional hardener~
in other words they ~ere pure gelatine layers, and proteotive
layer 6 contains 75~ by weight oi oompound 1, based on the
quantity of gelatinea
The material built up as de~oribed above has similar
properties to the material irom Example 1. The oourse of
hardening i~ slightly slower. There are no differenoes in
the stability oi~ the gradation.
Example 5
Example 1 is modified as iollows:
Intermediate layers Nos. 2 and 4 eaoh oontained 40 ml of a
3% aqueous triaoryloiormal solution per 10 1 oi 5~ gelatine
solution. Protective layer No. 6 contained 75 % by weight of
oompound 1, based on the quantity of gelatine,
The iollowing resultswere obtained with this material;
Hardenlng ~ the ~ame as in Example 1. Stability oi the
gradation oi the purple layer is sllghtly iniluenoed (re-
gression irom 2.85 to 2.34).
ExamPle 6
Example lw~ repeated but compound 3, 6~ 8~ 12~ 13~ 14
and 16 w~ used instead oi oompound 1 in the two intermediate
layers and in the proteotive layer.
A-G 1192 - 16 -
. ~
~, . .
1~6939
The results are represented in a simplified form in the
following table:
- CompoundFast to Boiling after Wat~r absorption in
days g/m after 4 weeks
3 5 47
6 8 45
8 7 40
12 7 42
13 9 45
14 6 40
16 7 42
.~
Example 7
Example 1 was repeated with the difference that the
given quantities of compound 1 in the two intermediate
-` 15 layers and in the protective layer were replaced by equal
quantities of triethylamine.
The following differences were found when the results
were compared with those of Example 1:
The advantageous effect of the amines according to the
invention is not obtained and the effect of triethylamine
on hardening of the test material is not reproducible,
particularly in high speed casting machines (casting velocity
25 to 50 m/min). A vacuum air brush casting machine was used
in which an emulsion layer was applied in one passage through
the machine and a protective layer was then applied after
solidification and drying o~ the emulsion layer. The amine
was ~ound to be so highly volatile that most of it was~ost
into the air used to solidify the layer and the odour given off
to the surroundings was intolerable. When casting machines
operating with circulating air were employed, the permissible
- A-G 1192 - 17 -
1066939
maximum concentration at the workplace (MAN value) was exceeded
so that protective respiratory apparatus must be used by the
operators. Experiments in which hardening was found to be accele-
rated also showed a corresponding increase in the fogging
produced in the heating cupboard (7 days, 57C, 34 % relative
humidity).
A-G 1192 - 18 -
