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Патент USA US2406621

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2,406,621
Patented Aug. 27, 1946
‘UNITED STATES PATENT OFFICE
2,406,621
7
METHOD OF PREPARING POLYSILOXANE
"
RESINS
James Marsden, Schenectady, N; Y., assignor to
'
General Electric Company, a corporation of
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<
v
New York
No Drawing. Application February 12, 1944,;
Serial No. 522.085
8 Claims. (Cl. 260-2)
2
This invention relates to a method of preparing
heat-hardenable' polysiloxane resins frequently
called silicone resins. It'is particularly concerned
with’ an improved method of hydrolyzing methyl
silicon chlorides, i. e., methyl. chloro derivatives
ing from 4 to 8 carbon atoms, preferably n
455,617, ?led August 21, 1942, and assigned to the
butanol, an aromatic hydrocarbon solvent, and
an aqueous solution of hydrochloric acid contain
ing at least 35 per cent by weight of hydrogen
chloride. The concentrated hydrochloric ‘acid
the hydrolyzing medium is preferably consider
make-up water, thus avoiding the loss of both sol-H
ably in excess of that calculated as necessary to
vents and acid.
of silane. including mixtures thereof with silicon
tetrachloride, to form heat-hardenable products. ‘
The application of Robert 0. Sauer, Serial No. 1
I
preferably an aromatic hydrocarbon solvent such
as toluene, benzene, or xylene, and slowly adding
the resultant solution to a two-phase hydrolyzing
medium comprising an aliphatic alcohol contain
same assignee as the present invention, describes 10 should be present in an amount exceeding that
calculated as necessary to provide su?iclent water
and claims a process of hydrolyzlng organo-sili
to hydrolyze the chlorosilane mixture. The aque
con halides, including mixtures thereof, with sili
ous or acid phase resulting from the hydrolysis
" con tetrahalides, which process comprises form
procedure contains upwards of 35 per cent, gen-~
ing a solution of the organo-silicon halides in an
inert, nonalcoholic organic solvent such as tolu 15 orally more than 40 per cent, hydrogen chloride
in addition to someof ‘the alcohol and aromatic
ene and adding the resultant product to a hy
hydrocarbon solvent in amounts corresponding to
drolyzing medium comprising a mixture of water .7
their solubiilties in such acid solutions. This
and a liquid aliphatic alcohol containing at least
phase can be‘ continually reused in subsequent
four,'but not more than-eight carbon atoms, such
hydrolyses generally with the addition of some
as n-butanol. The amount of water present in 20
' hydrolyze the;silicon halide. As a result, there is
obtained as a, by-product of the Sauer process a
The large quantity of gaseous
hydrogen chloride given on‘ during the hydrolysis
as a result of the fact that the hydrolysis medium
dilute solution of hydrochloric acid containing 25 is always saturated or substantiahy saturated
from 15 to 20 per cent, ordinarily about 17 told
with HCl maybe recovered in the practically an- v, .
per cent, by weight of hydrogen chloride and
hydrous state, in which form it is more readily
some of the solvents, such as n-butanol and tol
usableinindustry.
uene, used in the hydrolysis process.
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'
y
In order that those skilled in the art better may
In the commercial producticnof silicone resins 30 understand how the present invention ‘may be
carried into effect, the following illustrative ex
by the process of the Sauer application, using
amplesare given:
. .
water as a hydrolyzing medium, the disposal of
the dilute acid phase formed as a result of the
Example 1
hydrolysis represents a serious problem.‘ While
there is a limited use'for such dilute solutions of 35 A three-component mixture containing 59.4
molar per cent dimethyl dlchlorosilane, 22.8
hydrochloric acid, the solvents dissolved therein
molar per cent methyl trichlorosilane, and 27.8
represent an appreciable economic loss.
The present invention is based on my discovery
that the hydrolysis of mixtures of methyl chloro
molar per cent silicon tetrachloride was dissolved
in toluene in the ratio of 90 parts of the chloro
silanes (which term as used generally herein is in 40 silane mixture to 30 parts toluene. The resultant
solution was slowly added through a dropping
tended to include mixtures of methyl chlorosilanes
funnel to a mixture of 60 parts n-hutanol, 30 parts
with, silicon tetrachloride) containing vsuillcient
toluene, and 300 parts concentrated hydrochloric
chlorine vattached directly to silicon to form heat
acid contained in a 3-necked glass ?ask ?tted with
hardenable hydrolysis products can be carried out
in‘a saturated hydrochloric acid- solution in the 45 a_ stirrer, a thermometer, and a reflux condenser
presence of the solvents employed in the process .
of the Sauer application, and ‘that the concen
trated acidhphase resulting from the hydrolysis
may be reused in hydrolyzing additional methyl
containing carbon dioxide-acetone mixture as a
refrigerant. The hydrochloric acid employed in
this example contained about 37 per cent by
weight of hydrogen chloride. The hydrolyzing
bath was not cooled by any external means during
More speci?cally, I have found‘ 50
that a mixture of methyl chlorosilanes contain»
ing an average of more than two hydrolyzable
chlorine atoms per silicon atom can be converted
the hydrolysis‘ of the chlorosilane. During addi
tion of the chlorosilane solution to the hydrolysis
medium the temperature of the bath slowly rose
into heat-hard'enable polysiloxane resins by dis
tov a maximum of about 31 to 32.5“ C. and
chlorosilanes.
solving the mixture‘ in an inert organic solvent, '55 thereafter gradually dropped to about 25°v (2. due
2,406,621
3
to the evolution or gaseous hydrogen chloride.
silicon tetrachloride may be omitted @therei'rom
- After all of the chlorosilane solution had been
provided the mixture contains sumcient hydro
added, the resultant mixture was stirred for 5
lyzable chlorine atoms attached directly to silicon .
minutes, allowed to separate into two layers. and >
‘ so that .on hydrolysis, a. heat-hardenable methyl
the lower layer containing a 41 per cent solution
polysiloxane resin is obtained.
or hydrogen chloride in which'some bu'tanol and While n-butanol is the preferred alcoholic com
toluene were dissolved wasseparated from the - ponent of the hydrolysis mixture, satisfactory
upper resinous layer comprising a solution or the '
silicone resin in the remaining butanol and tolu
results may be obtained by the use or other alco
hols containing trom 4 to 8 carbon atoms. Exam
ene. - The resinous layer was washed with 200 10 ples of such alcohols are isobutyi alcohol, n-amyl
parts water and centriiuged to determine the gel >
alcohol, secondary amyl alcohol, isoamyl alcohol,
content. Based on the weight or the resin, the
amount 01' gel formed during hydrolysis was found
tertiary amyl alcohol, fuse] oil, z-ethyl butyl alco
to be about 0.4 per cent.
hol, methyl amyl carbinol, etc.
'
What I claim as, new and desire‘ to secure by
1
15
Example 2
A solution of 90 parts of the methyl chloro-'
silane mixture employed in Example 1 in 30
parts toluene was slowly added to an agitated
hydrolyzing medium consisting of 60 parts bu 20
tanol, 30 parts toluene, and 325.5 parts of the
Letters Patent of-the United States, is
1. The method of making polysiloxane resins
which comprises dissolving a mixture or methyl
chlorosllanes containing an average ’of more than
two chlorine atoms per silicon atoms in an arc
matic hydrocarbon solvent and slowly adding the
resultant solution to a two-phase hydrolysis
lower aqueous or acid layer obtained from Exam
medium comprisingan aliphatic alcohol contain
ple 1. No differences were noted during the
ing from 4 to 8 carbon atoms, an aromatic hydro
course of hydrolysis in Examples 1 and 2. The
carbon solvent, and an aqueous solution of hy
resinous layer was separated from the lower 25 drochloric, acid containing at least 35 per cent
aqueous layer and'washed with 200 parts water.
by weight of hydrogen chloride.
I
The resin was found to contain about 0.6 per
2. The method of hydrolyzing a mixture or
cent by weight of gel based on the weight of the
resin.
1
" methyl silicon chlorides and silicon tetrachloride
=
Example 3
containing an average of more than two chlorine
-
'30 atoms per silicon atom which comprises dissolv
A solution of 300 parts of a methyl chlorosilane
mixture having approximately the same compo
sition as that employed in Example 1 in 100 parts
ing said mixture in an aromatic hydrocarbon
solvent and slowly adding the resultant solution
to a two-phase hydrolysis medium comprising a
mixture of an aromatic hydrocarbon solvent, an
parts n-buta-nol, and 1188 parts of the aqueous 35 aliphatic alcohol containing from 4 to 8 carbon
atoms and a concentrated aqueous solution of
acid phase obtained from a previous hydrolysis
hydrochloric acid.
'
of methyl chlorosllanes. Fifty parts water was
3. The method or making polysiloxane resins
added to the resultant mixture and the hydro
‘which comprises forming a toluene solution of a '
lyzed resin was separated from the aqueous phase
and washed with water. The small amount of 40 mixture of methyl silicon chlorides and silicon
tetrachloride containing an average of more than
gel present therein was removed and the resin
two chlorine atoms per silicon atom and hydro
was concentrated and pre-condensed in accord- .
lyzing said mixture by slowly adding said solu
ance with the process described and claimed in
tion to a two-phase hydrolysis medium com
copending application Serial No. 455,615, ?led
Aug. 21, 1942, in the names of James G. E. Wright 45 prising a mixture of toluene, an aliphatic alcohol
containing from 4 to 8 carbon atoms, and a con
and James Marsden, now Patent No. 2,389,477,
centrated aqueous solution of hydrochloric acid.
issued Nov. 20, 1945, and assigned to the same
4. The method or making a polysiloxane resin
assignee as the present invention. The resin basev
which comprises dissolving a mixture of dimeth
content during pre-condensation was 25 per cent.
The resultant pre-condensed resin had a craze 50 yldichlorosilane, methyltrichlorosilane and silicon
toluene was slowly added to a mixture of 200
time at. 300° C._ of 166 hours, indicating that
resins hydrolyzed in accordance with the present
' invention may be readily substituted for those
tetrachloride in toluene, slowly adding the re
sultant solution tov a two-phase hydrolysis me
dium comprising toluene, an aliphatic alcohol
containing from 4 to 8 carbon atoms, and a
hydrolyzed in accordance with prior processes.
On continued reuse of the acid phase formed 55 quantity of concentrated aqueous ‘solution of
hydrochloric acid exceeding that calculated as
during hydrolysis of the methyl silicon chloride,
necessary for complete hydrolysis of the chloro
it is desirable to replace the water used up by
silane mixture, permitting the resultant mix
hydrolysis of the chlorosllanes and to replace
ture to separate into two layers, separating the
the butanol lost to the upper varnish or resin
phase. Ordinarily, about 50 parts water shouldv 60 resin phase and thereafter washing said resin
phase with water.
be added to the used hydrolysis medium for each
5. The method or making polysiloxane resins
300 parts'of chlorosllanes to be hydrolyzed. In
which comprises dissolving a mixture of methyl
' Example 3 the water added to the hydrolysis
chlorcsilanes containing an average or more than
mixture prior to separation of the ‘resin consti
' tutes the make-up water for the subsequent hy 65 two chlorine atoms per silicon atom in an arc
matic ‘hydrocarbon solvent and slowly adding the
drolysis of additional methyl chlorosllanes. A.
large part of the butanol present in the resin ~ resultant :solution to a two-phase hydrolysis me
‘dium comprising n-butanol. an aromatic hydro
layer can be recovered during concentration of
carbon »solvent, and an aqueous solution of hy
the varnish or resin traction.
‘
Wh?e the above examples describe the hy 70 drochloric acid containine at least 35 per cent
‘ drolysis of particular mixtures .of methyl chloro
sllanes and silicon tetrachloride, it is tube under
stood that the invention is not limited thereto.
For example,~some trimethyl silicon chloride may
be present in the chlorosilane'mixture and the 75
by weight or. hydrogen chloride.
-'
‘ 6. The method of hydrolyzing a mixture con
taining dimethyl silicon dichloride and silicon
tetrachloride which comprises dissolving said
mixture in an aromatic hydrocarbon solvent and
2,400,021
5
.
slowly adding the resultant'solution to a two
.phase hydrolysis medium comprising a mixture
or an aromatic hydrocarbon solvent, n-butanol,
and a concentrated aqueous solution of, hydro
chloric‘ acid.
‘
‘
.
"I. The method of. making polysiloxane resins
Q which comprises forming a toluene solution or a
‘ mixture of methyl‘silicon chlorides and silicon
tetrachloride containing an average of more than
.
'6
'
: 8. The method of making a polysiloxane resin
which comprises dissolving a mixture or dimeth
yldichlorosilane, methyltrichlorosilane, and sili
con tetrachloride in toluene, slowly adding the ‘
resultant solution to a two-phase hydrolysis me
dium compr‘sing toluene, n-butanol, and a quan
tity of a concentrated aqueous solution of hydro
chloric acid exceeding that calculated as neces
sary ior complete hydrolysis oi’ the chlorosilane
two chlorine atoms per silicon atom and hydro 10 mixture, permitting the resultant mixture to
lyzing said mixture by slowly adding said solu
tion to a two-phase hydrolysis medium compris
ing a mixture v0i.’ toluene,‘ n-butanol, and a con
centrated aqueous solution of hydrochloric acid.
separate. into two layers, separating the resin
phase and thereafter washing said resin phase _
with water.
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.
JAMES MARSDEN.
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