close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2407419

код для вставки
Patented Sept. 10, ‘194.6
2,407,419
UNITED‘ STATES PATENT OFFICE
STABILIZATION OF TETRAFLUORO
ETHYLENE
William Edward Hanford, Easton, Pa., assignor
to E. I. du Pont de Nemours & Company, Wil
I mington, Del., a corporation of Delaware
No Drawing. Application February 15, 1943,
Serial No. 476,025
10 Claims.
1
(C1. 260-652.5)
.
-
2
.
.
This invention relates to new compositions of
matter and more particularly to compositions
comprising ?uoroethylenes which are stabilized
a total of 6.5 months, during which time essen
tially no more polymerization takes. place.
against spontaneous polymerization.
Tetra?uoroethylene polymerizes after standing
lar conditions without the addition of ammonia,
the tetra?uoroethylene is completely ‘polymerized
a few days at room temperature under super
in less than one week.
. Ina control experiment carried out under simi
.
-
atmospheric pressure in accordance with the
Example II
teaching of U. S. Patent 2,230,654. This spon
To a glass tube similar toy that employed in
taneous polymerization of tetra?uoroethylene is
acutely undesirable since it necessitates costly 10 Example I is added about 0.1 part of p-pheneti
and time-consuming precautions for the safe
dine, and the tube is then immersed in a bath of
liquid ethylene and ?lled about half full of tetra
storing of tetra?uoroethylene. Thus prior to the
?uoroethylene (about 20 parts) by condensation.
present invention it has been an accepted prac
The tube is then transferred to a bath of liquid
tice to store tetra?uoroethylene at the tempera
ture of solid carbon dioxide since only in this 15 nitrogen, and after freezing, it is sealed. The
tube is then allowed to stand at roomrtempera
way could polymerization be prevented and tetra
ture, under which conditions the tetrafluoro
?uoroethylene stored in an appreciable quantity
ethylene is a liquid under its own vapor pressure.
over a period of time.
This invention has as an object the produc
After standing for 12' days there is formed only
tion of stabilized ?uoroethylenes which can be 20 a trace of polymer, corresponding to less than. 1%
of the total tetra?uoroethylene vpresent.
I
stored at normal temperature and superatmos
pheric pressure for an inde?nite period of time
Under similar conditions a control experiment
without undergoing spontaneous polymerization.
containing no stabilizer is completely polymerized
in less. than one week.
. . .
Other objects will appear hereinafter.
I havediscovered that this polymerization of 25
Example III ,
?uoroethylene compounds can be prevented by
Example II is repeated employing di-n-butyl
incorporating therewith a small proportion of a
amine instead of p-phenetidine as stabilizer. A
compound containing amine nitrogen and that
very small amount of polymer is formed in the
the stabilized product thus obtained can be stored
at normal temperature and superatmospheric 30 ?rst week of standing at room temperature, and
thereafter no further polymerization occurs for
pressure for an inde?nite period of time without
six months. The total quantity of ‘polymer
undergoing polymerization. For example, tetra
formed corresponds to less than 1% by weight
?uoroethylene to which is added about 0.1% to
of the total tetra?uoroethylene present.
1% by weight of tributylamine undergoes no
spontaneous polymerization whatever on storage
Example IV
under its own vapor pressure at 25° 0., whereas
unstabilized tetra?uoroethylene undergoes ap
preciable polymerization in a few days under
such conditions.
'
The invention is further illustrated by the fol
lowing examples:
Example I
85
Example II is repeated employing tri-n-butyl
amine in place of p-phenetidine as stabilizer. No
polymerization whatever occurs under these con
40 ditions after the tube has stood at room tempera
ture for 6.25 months.
Example V
A thick walled glass tube is ?lled about half
Tetra?uoroethylene stored in the absence of its
full of liquid tetra?uoroethylene by condensing 45 liquid phase under 200 lbs/sq. in. pressure at
the tetra?uoroethylene while the tube is im
mersed in a bath of liquid ethylene. The free
space in the tube is then ?lled with ammonia
room temperature in a steel container undergoes
some spontaneous polymerization after standing
for about a month.
However, the addition of
gas, the tube isv placed in liquid nitrogen to freeze
0.5% by weight of tributylamine to the storage
the tetrafluoroethylene and it is sealed. The tube 50 container effectively and completely prevents this
is then allowed to stand at room temperature,
polymerization over a period of more than six
under which conditions the liquid tetra?uoro
months.
ethylene is under its own vapor pressure. After
one week but a trace of polymer has formed in
The ?uoroethylene compounds referred to here
I in are halogenated ethylene compounds contain
the glass tube. The tube is allowed to stand for 55 ing at least one ?uorine atom. Examples of these
2,407,419
4
scrubbing with an acid solution or by passing the
compounds are vinyl ?uoride, 1,1-di?uoroethyl
ene, l-?uoro-l-bromoethylene, l-?uoro-Z-chloro
gas over an absorbent for the stabilizer.
As many apparently widely different embodi
ments of this invention may be made without de
parting from the spirit and scope thereof, it is to
chloroethylene and tetra?uoroethylene. The
be
understood that I do not limit myself to the
process of this invention is particularly suitable
speci?c embodiments thereof except as de?ned in
for the stabilization of poly?uoroethylenes, i. e.,
the appended claims.
those containing more than one ?uorine atom.
I claim:
The amino compounds, in addition to those dis
1. A process for treating tetrafluoroethylene
closed in the examples, which can be used as the
which substantially reduces its tendency to spon
polymerization stabilizers include a large number
taneous polymerization at normal temperature
of available compounds, examples of which are
and superatmospheric pressure, said process com
primary aliphatic amines, such as ethylamine and
prising mixing with said tetrafluoroethylene a
butylamine; secondary aliphatic amines, such as
dihexylamine and methylbutylamine; tertiary ali 15 small amount of tertiary hydrocarbon amine.
2. A process for treating tetra?uoroethylene
phatic amines, such as trimethylamine and tri
which
substantially reduces its tendency to spon
e'thylamine; primary aromatic amines, such as
taneous polymerization at normal temperature
beta-naphthylamine' and aniline; secondary aro
and superatmospheric pressure, said process com
matic amines, such as diphenylamine and phenyl
prising mixing with the tetra?uoroethylene a
20
alpha-naphthylamine; tertiary aromatic amines,
small amount of a tertiary aliphatic hydrocarbon
such as triphenylamine; mixed secondary amines,
amine.
‘
such as N-monomethyl aniline and N-propyl ani~
3. A process for treating tetra?uoroethylene
line; and mixed tertiary amines, such as N-di—
which substantially reduces its tendency to spon
methyl aniline and N-butyl diphenylamine. The
taneous polymerization at normal temperature
stabilizers of this invention may be further ohar~
and superatmospheric pressure, said process com—
acterized in that they are basic compounds con
prising mixing with said tetra?uoroethylene a
taining amino nitrogen, i. e., they include am
small amount of tributyl amine.
monia and substituted ammonias in Which one or
ll. Tetra?uoroethylene stabilized with sufficient
more of the hydrogen atoms is replaced by alkyl, I ' tertiary hydrocarbon amine to prevent polymeri
alkaryl, aralkyl, or aryl hydrocarbon radicals.
zation of the tetra?uoroethylene at 25° C. and
The stabilizer is to be employed in amounts
superatmospheric pressure.
ranging from about 0.001% to about 5%, based
5. Tetra?uoroethylene stabilized with sufficient
ethylene, 1,Z-di?uoro-1,2-dich1oroethylene, 1,1
di?uoro - 2,2-dichloroethylene,
1,1,2-tri?uoro-2
on the monomer. In general, however, it is pre
ferred to employ the stabilizers in amounts rang
ing from about 0.01% to about 1%, based on the
amount of monomer.
Fluoroethylene compounds which are stabilized
according to the method given in this invention
can be stored inde?nitely without danger of poly
merization. On the contrary, the unstabilized
compound'polymerizes on standing, either com
tertiary aliphatic hydrocarbon amine to prevent
polymerization of the tetra?uoroethylene at 25° C.
and superatmospheric pressure.
6. Tetra?uoroethylene stabilized with su?icient
tributylamine to prevent polymerization of the
tetra?uoroethylene at 25°
pheric pressure.
7. The process set forth
said tertiary hydrocarbon
amount of from 0.001% to
pletely ?lling the container with solid polymer or
?lling the exit valves, so that the removal of the
remainder of the unpolymerized material is im
possible.
undesirable but also dangerous, it is of great ad
vantage to be able to store fluoroethylenes in
and by means of stabilizers which are readily re
moved from the monomer. It is not essential that
in claim 1 in Which
amine is added in
5% by Weight of the
tetra?uoroethylene.
Since such circumstances are not only '
de?nitely without danger of such polymerization
C. and superatmos
8. Tetra?uoroethylenestabilized with tertiary
hydrocarbon amine in amount of from 0.001% to
5% by weight of the tetra?uoroethylene.
9. Tetra?uoroethylene stabilized with tertiary
aliphatic hydrocarbon amine in amount of from
50" 0.001% to 5% by weight of the tetra?uoroethyl
the stabilizers of this invention be removed prior
ene.
to catalytic polymerization of the ?uoroethylene.
10. Tetra?uoroethylene stabilized with tribu
tylami’ne in amount of from 0.001% to 5% by
However, if desired this removal can be accom
weight of the tetra?uoroethylene.
plished, for example, by fractional distillation, by 55.
WILLIAM EDWARD HANFORD.
Документ
Категория
Без категории
Просмотров
0
Размер файла
275 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа