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Патент USA US2113517

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Patented‘ Apr. ‘5, 1938v -
' 2,113,511
. ~ , UNITEDSTATES PATENT OFFICE
2,113,517
ELECTRODEPO SITION 0F SILVER
Alan Richard ’Powell and Emyr Conwy Davies,
London, England, assignors to Johnson, Mat
they & Company, Limited, London, England,
I
a British company
No Drawing. Application October 5, 1936, Se
'
'
rial No. 104,149.
In Great Britain January 26,
1935 -
9 Claims.
(Cl. 204-46)
‘ This invention relates to the electrodeposition
of silver and has for its main object to provide a
calcium or magnesium compound which forms a . ,
plating bath‘ from which hard bright deposits of
silky precipitate and gives the bath an opalescent
appearance which, however, does not interfere
sliver of any desired thickness can be obtained.
with the production of bright silver plates. ' A
Present practice in silver plating i’rom cyanide small quantity of glycerine or of 'a glycol may be
baths produces a matt deposit which requires added to the bath to reducestill further the grain
polishing to develop a bright lustrous surface and size of the deposit. Obviously, the soap may be
this polishing not only adds to the cost of plating produced in situ in the bath by the addition of
but removes a considerable proportion of silver
10 which is lost.
‘
It is well known that the addition of organic
, sulphides, such as carbon disulphide, to the nor
free acid,as for example sulphonated acid in the ,
10
form commonly known as Turkey red oil.
Deposits obtained from the improved baths
according to this invention are much harder than
mal plating bath tends to produce smoother and those obtained in the ordinary silver bath and .
' brighter deposits of silver but the advantages to have a brilliant white lustre which requires little
be obtained are not su?lciently marked nor so
constant as to warrant its use being generally
‘ adopted.
It is also well known that silver plating baths
containing excessive amounts of free alkali metal
20 cyanide produce very hard matt deposits which
are di?icult and costly to polish. For this reason
the amount of free alkali metal cyanide is usually
kept down to the minimum required for satis
factory plating.
We have now found that the advantageto be
25
obtained by the use of organic sulphides selected
from the group carbon disulphide and mereaptans
which are soluble in the bath, in respect to bright
ness of deposit and the advantage of increased
amounts of free alkali metal cyanide as regards
30
hardness of deposit canibe combined and con
siderably enhanced by the further addition to
the normal plating bath of a colloidal solution
of a detergent. The term detergent in the speci-.
35 ?cation‘ and claims means an alkali metal salt
of a soap-forming acid, such as a monobasic sat
urated or unsaturated carboxylic or hydroxycar
boxylic acid of\ the aliphatic series containing
not less than eight carbon atoms in the molecule,
or or an alkali metal salt of a sulphonic acid
derived from one of thessaid soap-forming acids
or from the corresponding alcohol. The addition
made to a cyanide bath to produce a bright silver
plate may thus consist of any of the commercial
45 forms of soap, including sulphonated soaps. All‘
these compounds tend to hydrolyze in solution
50
or no polishing.
There are therefore no losses 15
of silver due to polishing and silver plating costs
are consequently very substantially reduced.
The free alkali metal cyanide content of the
plating bath may vary within wide limits, for
example from 1 to 16 ounces per gallon, with 20
corresponding effects upon the hardness of the
deposited silver.
'
The sulphide brightening solution is added to
the plating solution from time to time as required.
This brightening solution is prepared by saturat 25
ing a portion of the plating liquor or-alternatively
an alkali metal cyanide solution with carbon di-'
sulphide and returning the sulphide solution ob
tained to the plating bath"
‘
The following examples will further illustrate 30
how the said invention'may be carried out vin
practice, but the invention is not restricted to
‘these examples.
'
'
Example 1
A bath is prepared as follows:
Ounces per gallon
‘ __‘ 2. 0
. Silver (as KAg(CN)z)_____' ______________
Free potassium cyanide _________________ __ 8.0
Turkey‘ red oil _________________________ __>_ 0.75 >
Sulphide brightening solution (obtained as
described
above) ____ -r ___________ _>__'___
Example 2
A bath is'prepared as follows:
45
Ounces per gallon
Silver (as KA¢(CN):) ___________________ __ 3.0
free acid in a colloidal form which appears to be
Free potassium cyanide ______________ __'____6.0
adsorbed to a small extent by the deposit, thus
Castile soap (sodium oleate) ____________ __ 3.0
producingia ?ne-grained structure consisting of. Sulphide brightening solution (obtained ‘as
,
When a soap is used, the amount required de
pends on the‘nature oi the soap, but should be
sumcient to produce a permanent lather when
55 the solution is shaken and should of course not
exceed the solubility of the soap in the solution.
When the bath is made up with soft water, about‘
0.1 ounce of soap per gallon is sumcient, but
when made up with hard water more is required
since part is converted into the corresponding
40
0:15".
with the production 01 a'srnall quantity of the
almost sub-microscopic crystals.
35
50
described above) ________________ __'_____ 0.75
The baths described are preferably operated at
room temperature and with a current density
‘between 1 and 8 amperes per square foot. Higher 55
current densities tend to produce “burnt depos
its”.
What we claim
.
1. A process‘ior the electrodeposition of silver,
in the form of hard bright deposits requiring
2,113,517
little or no polishing, from an alkali metal cyanide
5.'A ‘plating bath comprising an alkali metal
' ' bath comprising an alkali metal argento-cyanide,
argento-cyanlde, an excess or free alkali vmetal
cyanide, an organic sulphide of the group con
an excess of free alkali metal cyanide and an
organic sulphide of the group consisting of car
bon disulphide and mercaptans which are solu
ble in the bath, which consists'inadding to the
said bath a colloidal solution of an alkali metal
salt of an acid of_ the, group consisting of all
phatic acids‘ containing no less than eight car
bon atoms in the molecule, sulphonic‘ acids de
‘ acids derived from the alcohols corresponding to
said aliphatic acids._
acid of the group consisting of aliphatic acids
containing no less than eight carbon atoms in the
phatic acids, and sulphonic. acids derived from
the alcohols corresponding to said aliphatic‘acids. 10
6. A plating bath comprising a potassium ar
gento-cyanide, an excess of freepotassium cya
nide, carbon disulphide and Turkey red oil.
2. A process for the electrodeposition 01 silver,
15 in the form of hard bright deposits requiring little
or‘no polishing, from an alkali metal cyanide
bath comprising an alkali metal argento-cyanide,
an excess of tree alkali metal cyanide and an
organic sulphide of the groupconsisting of car
20 bon disulphide and mercaptans which are solu
ble in the bath, which consists in adding to ‘the
said bath a commercial soap, including sul
'
>
-
.3. In the process 01' electrodepositing silver
from a bath comprising an alkali metal argento
cyanide, an excess of free alkali metal cyanide,
an organic sulphide of the group consisting of
carbon disulphide and mercaptans which are
‘ ‘soluble in the bathand an alkali metalsalt oi’
an acid of the group consistingoi aliphatic acids
containing no less‘than eight carbon atoms in
the molecule, sulphonic acids derived from said
, aliphatic acids, and sulphonic acids derivedi'rom
the ‘alcohols corresponding to said aliphatic acids,
the step of introducing the organic sulphide in
the form ‘of a sulphide brightening solution pre
pared by saturating a portion of the plating liquor
with carbon disulphide and returning the sul
phide solution to the‘plating bath.
40
soluble in the bath, and an alkali metal salt of an '
molecule, sulphonic acids derived from said ali- '
10. rived from said aliphatic acids, and sulphonic
phonated soaps.
sisting of carbon disulphide and mefcaptans'
J
4. In‘ thexp'rocess of electrodepositing silver
from a bath'comprising an alkali metal argento~
cyanide, an excess of free alkali metal cyanide,
an organic sulphide of the group consisting of,
\
'7. A plating bath comprising a potassium ar
gento-cyanide, an excess of free potassium cya 15
nide, carbon disulphide and commercial sodium
oleate (castile soap).
'
.
8. A process for the electrodeposition of silver,
in‘ the form or hard bright deposits requiring
little or, no polishing, from an alkali metalcya+ 20
nide bath comprising, an. alkali metal argento
cyanide, an excess of tree metal cyanide, and an
Y organic sulphide'ot the group consisting oi.’ car
bon disulphide and mercaptans soluble in the
bath, which consists} in adding to the said batli 25
an alkali metal salt of an acid of the group con
sisting of aliphatic acids containing no less than
eight carbon atoms in the molecule.
'
9. A process for the electrodeposition of silver
in the form of hard bright deposits requiring 30
little or no polishing,'irom an alkali metal cya
nide bath comprising an alkali metal argento~
cyanide, an-‘excess oi‘ free alkali metal cyanide,
and an organic sulphide of the'group consisting
of carbon bisulphide and mercaptans which are 35
soluble in the bath, which consists in adding to
the said bath a colloidal solution of an alkali
metal salt 01" a soap forming acid which tends
to hydrolize in solution with the production of a 40
small quantity of the free acid in a colloidal form‘
which appears to be adsorbed to a small extent
by the deposit, thus producing a ?ne grained
carbon disulphide and mercaptans which are; structure consisting 01’ almost subarthroscopic;~
soluble in the bath and an alkali metal salt of ..crystals. said soap forming acidwbeing, selected 45
an acid oi the group consisting oi aliphatic acids from the group consisting of monobasic saturated '
containing no less than eight carbon atoms in or unsaturated, carboxylic or hydroxycarboxylic
the molecule, sulphonic, acids derived from said
aliphatic acids. and sulphonicacids derived from
the alcohols corresponding to said aliphatic acids,
acids of the aliphatic-‘series containing not less
than eight carbon‘ atoms in the ‘molecule, sul
phonic acids derived trom the said aliphatic acids,
the step of introducing the organic sulphide in v and sulphonic acids derived from the alcohols
the form of a sulphide brightening solution pre
pared by saturating an alkali metal cyanide solu
tion with carbon disulphide and returning the
corresponding to said aliphatic acids.
Y ALAN RICHARD POWELL.
mumv com DAVIES.
sulphide solution to the plating bath.
vPatent llO- - 2,113,517;
-~
/
' HCERTIFlGATE
I ‘I
- oF’coRREcr1oN.=_~_
'
"
V
'
'
"
I
m1; $."l95a.
ALAN RIQHARojrowsLLr-Er AL,
. It is "hereby certified ‘that error appears
"the printed specificationcl
‘ “or the above mniibered' patent requiring correction as roiiows : ' Page-1'," second . '
’ '-col.umn,. line 9-, 'beroretheword "acid'i'ineert ricinoleicgandthat ‘the said
I Letters Patent shouldbe read wit-ih-thzls~ correction- therein that the same
my man tofthefrecordhor the-case '11; the Patent'0f?ce._ ' '
Signed “assassins 51st day army, a." Dr; 1958;
- ,
(Seali
. '
ilierryfllan
.» '
- ,n-of Patents,
2,113,517
little or no polishing, from an alkali metal cyanide
5.'A ‘plating bath comprising an alkali metal
' ' bath comprising an alkali metal argento-cyanide,
argento-cyanlde, an excess or free alkali vmetal
cyanide, an organic sulphide of the group con
an excess of free alkali metal cyanide and an
organic sulphide of the group consisting of car
bon disulphide and mercaptans which are solu
ble in the bath, which consists'inadding to the
said bath a colloidal solution of an alkali metal
salt of an acid of_ the, group consisting of all
phatic acids‘ containing no less than eight car
bon atoms in the molecule, sulphonic‘ acids de
‘ acids derived from the alcohols corresponding to
said aliphatic acids._
acid of the group consisting of aliphatic acids
containing no less than eight carbon atoms in the
phatic acids, and sulphonic. acids derived from
the alcohols corresponding to said aliphatic‘acids. 10
6. A plating bath comprising a potassium ar
gento-cyanide, an excess of freepotassium cya
nide, carbon disulphide and Turkey red oil.
2. A process for the electrodeposition 01 silver,
15 in the form of hard bright deposits requiring little
or‘no polishing, from an alkali metal cyanide
bath comprising an alkali metal argento-cyanide,
an excess of tree alkali metal cyanide and an
organic sulphide of the groupconsisting of car
20 bon disulphide and mercaptans which are solu
ble in the bath, which consists in adding to ‘the
said bath a commercial soap, including sul
'
>
-
.3. In the process 01' electrodepositing silver
from a bath comprising an alkali metal argento
cyanide, an excess of free alkali metal cyanide,
an organic sulphide of the group consisting of
carbon disulphide and mercaptans which are
‘ ‘soluble in the bathand an alkali metalsalt oi’
30 an acid of the group consistingoi aliphatic acids
containing no less‘than eight carbon atoms in
the molecule, sulphonic acids derived from said
, aliphatic acids, and sulphonic acids derivedi'rom
the ‘alcohols corresponding to said aliphatic acids,
the step of introducing the organic sulphide in
the form ‘of a sulphide brightening solution pre
pared by saturating a portion of the plating liquor
with carbon disulphide and returning the sul
phide solution to the‘plating bath.
40
soluble in the bath, and an alkali metal salt of an '
molecule, sulphonic acids derived from said ali- '
10. rived from said aliphatic acids, and sulphonic
phonated soaps.
sisting of carbon disulphide and mefcaptans'
J
4. In‘ thexp'rocess of electrodepositing silver
from a bath'comprising an alkali metal argento~
cyanide, an excess of free alkali metal cyanide,
an organic sulphide of the group consisting of,
\
'7. A plating bath comprising a potassium ar
gento-cyanide, an excess of free potassium cya 15
nide, carbon disulphide and commercial sodium
oleate (castile soap).
'
.
8. A process for the electrodeposition of silver,
in‘ the form or hard bright deposits requiring
little or, no polishing, from an alkali metalcya+ 20
nide bath comprising, an. alkali metal argento
cyanide, an excess of tree metal cyanide, and an
Y organic sulphide'ot the group consisting oi.’ car
bon disulphide and mercaptans soluble in the
bath, which consists} in adding to the said batli 25
an alkali metal salt of an acid of the group con
sisting of aliphatic acids containing no less than
eight carbon atoms in the molecule.
'
9. A process for the electrodeposition of silver
in the form of hard bright deposits requiring 30
little or no polishing,'irom an alkali metal cya
nide bath comprising an alkali metal argento~
cyanide, an-‘excess oi‘ free alkali metal cyanide,
and an organic sulphide of the'group consisting
of carbon bisulphide and mercaptans which are 35
soluble in the bath, which consists in adding to
the said bath a colloidal solution of an alkali
metal salt 01" a soap forming acid which tends
to hydrolize in solution with the production of a 40
small quantity of the free acid in a colloidal form‘
which appears to be adsorbed to a small extent
by the deposit, thus producing a ?ne grained
carbon disulphide and mercaptans which are; structure consisting 01’ almost subarthroscopic;~
soluble in the bath and an alkali metal salt of ..crystals. said soap forming acidwbeing, selected 45
an acid oi the group consisting oi aliphatic acids from the group consisting of monobasic saturated '
containing no less than eight carbon atoms in or unsaturated, carboxylic or hydroxycarboxylic
the molecule, sulphonic, acids derived from said
aliphatic acids. and sulphonicacids derived from
the alcohols corresponding to said aliphatic acids,
acids of the aliphatic-‘series containing not less
than eight carbon‘ atoms in the ‘molecule, sul
phonic acids derived trom the said aliphatic acids,
the step of introducing the organic sulphide in v and sulphonic acids derived from the alcohols
the form of a sulphide brightening solution pre
pared by saturating an alkali metal cyanide solu
tion with carbon disulphide and returning the
corresponding to said aliphatic acids.
Y ALAN RICHARD POWELL.
mumv com DAVIES.
sulphide solution to the plating bath.
vPatent llO- - 2,113,517;
-~
/
' HCERTIFlGATE
I ‘I
- oF’coRREcr1oN.=_~_
'
"
V
'
'
"
I
m1; $."l95a.
ALAN RIQHARojrowsLLr-Er AL,
. It is "hereby certified ‘that error appears
"the printed specificationcl
‘ “or the above mniibered' patent requiring correction as roiiows : ' Page-1'," second . '
’ '-col.umn,. line 9-, 'beroretheword "acid'i'ineert ricinoleicgandthat ‘the said
I Letters Patent shouldbe read wit-ih-thzls~ correction- therein that the same
my man tofthefrecordhor the-case '11; the Patent'0f?ce._ ' '
Signed “assassins 51st day army, a." Dr; 1958;
- ,
(Seali
. '
ilierryfllan
.» '
- ,n-of Patents,
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