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Patentecl Nov. 12, 1946
2,411,033
l UNrrsc ¿stars-5s PATENT o'FrlÍcE2,411,033
'PROCESS FOR THE COAGULATION 0F
CASTILLOA LATEXv
l >'iCîrey Foster ¿Forth Arlington, Va., assigner to
United States of America, as represented by the
' Secretary of Agriculture
'
Original application August, 31, i
1943, Serial No. 500,649. Divided and this ap
v No Drawing.
plication November 23, 1945, Serial No. 630,517
3 Claims.
(Cl. 260-821)
(Granted under the act of March 3, 1883, as
amended April 30, 1928; 370 0. G. 757)
l
This application is made under the act of
March 3, 1883, as amended by the act of April 30,
1928, and the invention herein described, if pat
2
only Within a narrow concentration range and is
less satisfactory than the results which can be
obtained by additional use of an acid substance.
ented, may be manufactured and used by or for
With tri-sodium phosphate and sodium carbonate,
the Government of the United States of America 5 coagulation is not brought about as easily nor is
for governmental purposes without the payment
the coagulum as workable as obtained by using an
to me of any royalty thereon.
This application is a division of copending ap-
, alkaline substance and an acid substance or salts.
Tri-sodium phosphate and sodium carbonate are
plication for patent, Serial No. 500,649, filed
probably effective because they are strongly alka
August 31, 1943.
1o line salts, and are capable both of dissolving the
This invention relates to the coagulation of
Castilloa latex which in its natural state is nor-
protective proteins and of precipitating the re
sulting colloidal systems.
`
mally stable when treated With acids, and has
The following examples, each employing a
among its objects a process for the coagulation
sample of 15 cc. of undiluted Castilloa latex, which
of such latex in a simple manner.
15 had not been previously treated by “washing” or
Hevea rubber latex is readny coagulabie by acid
otherwise, are illustrative of the process of coag
substances and such coagulation is an essential
ulation of this invention.
step in most commercial methods of preparing
Example I
I-Ievea rubber. Similar methods cannot be used
with Castilloa latex. Commercial 'development 20
A mixture 0f the Sample 0f 131119K and 1 CC- 0f
of casuuoa rubber has been retarded by the dir10 Percent NaOH gave n0 Coagulum in the @01d
ficulty and uncertainty of the primitive methods
01' 0n Warming- Addition 0f 1 CC- 0f 18 percent
now in use in ooagulating its latex
HC1 to the heated mixture immediately produced
I have found that Castilloa latex can be coaga» Coagulnln Which Was @Onerent and of good tex
ulated by acid substances and salts used for coag- 25 tum 5111111511’ results Were Obtalned by repeat
mation of Hex/eau latex, provided the oasmioa
ing the Process, except that the beaune Was a0
latoX ¿s mst treated with dilute ammonia, oaus_
tic soda, or other alkaline substances, and in the
complished‘after the treatment with the hydroxide
and the 3md
oaso of aoid Substances suon are used in Sun-j-
Instead of using HC1, good results were also ob
cient quantity to neutralize the alkaline substance 30 tained by using 1 CC- 0f 10 peI‘Cenlì I‘12504, 2 C0
and coagulate the rubber. Gentle heating is nec0f 10 Percent acefßïc acid’ 0r 1 CC- 0f 10 percent
essary to produce rapid and satisfactory coagu1131304- COagU-latlon Was 3150 Produced by “Sing
lation and clumping of the rubber, but the heat1% CC- 0f 10_Pe1`0ent formi@ acid’ ‘but the Coagu
ing can be at any time during or after addition
111m Was gramy.
of the alkaline and acid substances or salts.
35
Example II
Although the mechanism of_ the treatment is
A mixture of the sample of latex and 1 ca_ of
not known, probably 1ts effect 1s to dissolve substances other lthan rubber from the surfaces of
the latex partlcles. So long as these substances,
10 no1-Cont NaOH gave no ooagnlum in one cold
or on Warming on adding 10 oo_ of 10 percent
NaCl’ a ooagulnm Was obtained which was only
which are probably proteins, coat .the particles, 40 loosely coherent,
A compact, though grainy,
they cause the part1cles to be pos1t1vely charged,
ooagulum was obtained by substituting 2 oo_ of
and therefore, to be uncoagulated by positive ions.
10 percent Cock for tno NaCL
Removal of these substances by the alkaline subThe sans mentioned above when used alone did
stance does not of itself produce coagulation, benot produce Coagulation
cause negative rubber particles remain, which, 45
like Hevea latex particles, are stabilized by alkaExample IH
line substances. Like Hevea latex particles, however, they are noW coagulable by acid substances
and salts used for coagulation of Hevea latex.
A mixture of the sample of latex and 2 cc. of
10 percent NaaPO4 gave on heating a grainy, non
coherent coagulum. Addition of 1 cc. of 10 per
I have also found that use of certain alkaline 50 cent HC1 and slight boiling produced clumping of
substances, including alkaline salts such as trithis coagulum. A mixture of the sample of latex
sodium phosphate and sodium carbonate, and
and 2 cc. of 10 percent NazCOa gave on heating a
even sodium hydroxide and ammonium hydroxloose coagulum.
ide, can produce coagulation alone. In the use
Heating the untreated latex or boiling it alone
of sodium hydroxide, however, coagulation occurs 55 did not produce coagulation. Neither was coagu
2,411,033
3
lation produced by making the latex only slightly
alkaline and then slightly acid, using litmus pa
pers as indicators, even when followed by long
heating.
Having thus described the invention, what is C1
claimed is:
1. A process for coagulation of Castilloa latex
comprising treating untreated Castilloa latex
with dilute NaOH in the ratio of about 15 parts
of the latex to one part of the NaOH, and then l0y
with an acid substance in suiiicient quantity to
neutralize the NaOH and coagulate the rubberl
and heating to facilitate coagulation of the rub
ber.
4
2. A process for coagulating Castilloa latex
comprising treating untreated Castilloa latex with
dilute NaOH in the ratio of about 15 parts of the
latex to one part of the NaOH and then with
about 10 parts of dilute NaCl solution, and heat
ing to facilitate coagulation of the rubber.
3. A process for coagulating Castilloa latex
comprising treating untreated Castilloa latex with
dilute NaOH in the ratio of about 15 parts of the
latex to one part of the NaOH and then with
about ‘2 parts of dilute CaCl: solution, and heat
ing to facilitate coagulation of the rubber.
TIREY FOSTER FORD.
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