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Патент USA US2407602

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Patented Sept. 10, 1946
. '
‘. Frederic R. Bean, Rochester, N. Y., assignor to >
‘ Eastman Kodak CompanyLRooheSter, ,N. Y., ‘a;
corporation of New Jersey
No Drawing. Application March 3, 1945,
Serial No. 580,925
2 Claims.
(CI. 95-88)
This invention relates to photographic devel
glassy liquid was formed in about 30—45 minutes.
opers, and more particularly to developers in
which the usual alkalies are replaced by a com
position new for the purpose.
One object of my invention is to provide an air
stable, moisture-resistant alkali for use in pho
tographic developers. Another object is to pro
vide an alkali which will give, in photographic
It was spread out and dried in a thin layer at 40°
C. The product was ground to a white powder
which was completely stable under ordinary at
mospheric conditions. The yield was practically
A mixture of anhydroformaldehyde sulfanilate
and sodium sul?te is stable and non-deliquescent,
and does not absorb carbon dioxide from the air.
and results as sodium hydroxide. Another object 10 It can be weighed, stored and handled with ease.
is to provide a stable, noncaking, ready-mixed, dry
When this mixture is dissolved in water, the fol
developer powder. Still another object is to pro
lowing reaction takes place:
vide a stable, non-caking, ready-mixed, single dry
developers, approximately the same alkalinity
developer powder. Other objects will hereinafter
Alkaline developers have been known and used
for many years.
+ NarSOa + H10 _-» O + NaOH
These developers usually con
tain developing agents, a so-called preservative,
such as sodium sul?te, and an alkali. One of the
oldest and most useful alkalies used'in photo 20
The pH of a solution made by dissolving a gram
graphic developers is sodium hydroxide, otherwise
mole of sodium anhydroformaldehyde sulfanilate
known as caustic soda. The degree of alkalinity
and a gram-mole of sodium sul?te in a given
which it confers upon a developer has been found
amount of water is practically the same as that of
to be most suitable for certain purposes. How
ever, sodium hydroxide is deliquescent and corro~ 25 a solution made by dissolving a gram-mole of so
dium hydroxide in the same amount of water. An
sive, and for this reason is di?icult to handle,
equimolecular mixture of sodium anhydroformal
dehyde sulfanilate and sodium sul?te can be used
weigh, store and package. Moreover, when used
in ready-mixed, packaged developer powders,
in place of sodium hydroxide, 333 ‘parts by weight
which, because of their convenience and uniform
ity, are very popular among both amateur and 30 of the mixture replacing 40 parts by weight of
sodium hydroxide, in all photographic developer
professional photographers, sodium hydroxide is
formulae in which sodium hydroxide is speci?ed.
apt to cause caking, discoloration and deteriora
The compound
tion of the powder. This renders impracticable
the preparation of a single-powder developer con
taining sodium hydroxide.
I have discovered that a mixture of equimolec
ular proportions of sodium sul?te and sodium an
hydroiormaldehyde sulfanilate is suitable for use I
in photographic developers in which it is desired
S OaNa
to have the alkaline properties of sodium hydrox 40
ide without its undesirable properties.
formed when the mixture of sodium anhydro
Sodium anhydroformaldehyde sulfanilate has
formaldehyde sulfanilate and sodium sul?te is
the structural formula
dissolved in water acts as a moderately strong
It also exerts a restraining
action on photographic development. Therefore,
a developer made up with this mixture shows less
photographic activity than one made up with an
equivalent amount of sodium hydroxide even
though the pH is the same in both cases.
An equimolecular. mixture of sodium anhydro
formaldehyde sulfanilate and sodium sul?te can
be used to prepare single-powder developers, since
it does not react upon the other dry chemicals
On warming to 90°-100° 0., a 55 present in the powder. It will be understood that
and may be prepared as follows:
Example 1._231 g. of sodium sulfanilate were
mixed with '75 g. of a 40% aqueous solution of
stabilizing agent for alkaline solutions of photo
45 graphic developers.
additional sodium sul?te beyond that required to
make an equimolecular mixture with the sodium
anhydroformaldehyde sulfanilate may be, and us
ually will be, employed in the developer, to per
mately together in a single container and remains
stable in dry form; without discoloration.
What I claim as my invention and desire to be
secured by Letters Patent of the United States is:
1. _A photographic developer, in dry form, con
form its usual function as a preservative.
taining a developing agent and, as an alkali, a
As an example of a single-powder developer
mixture, in equimolecular amounts,1of sodium an
containing my novel mixture, I give the following:
hydroformaldehyde sulfanilate and sodium sul?te.
Hydroquinone ___________ -.g._
6. 0
Elon _________ --
l. 5 For use dlssolve in 300 m1. of‘
Sodium sul?te ___________ __g_. 24.0
Water at about 125 F. (5(1a
sulfanilate ___________ __g..
Potassium bromide_ ___g_'_
requisite for use.
Sodium anhydrofor ald hyde
l. O
0.); cool to temperature
This developer has all ingredients mixed inti; '
2. A photographic developer in the form of a >
single dry powder, containing a developing agent '
and, as an alkali, a‘ mixture, in'equimolecular
amounts, 'of sodium anhydroformaldehyde sulf
' am‘late and. sodium sul?te.
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