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Description  |
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The present invention relates to organic polymers containing silicon atoms,
particularly to silylated organic polymers and more particularly to
silylated organic-organopolysiloxane block copolymers.
Heretofore, copolymers have been prepared by reacting alkali metal
terminated organic polymers free of silicon atoms with cyclic siloxanes.
(See U.s. Pat. Nos. 3,483,270 and 3,051,684 to Bostick and Morton et al,
respectively.) However, neither of these references disclose the formation
of silylated polymers by reacting alkali metal terminated organic polymers
with silicon compounds having aliphatic unsaturation of form organic
polymers containing silicon atoms. Moreover, these references do not
disclose silylated organic-organopolysiloxane block copolymers or a method
for preparing the same.
Therefore, it is an object of this invention to prepare silylated organic
polymers. Another object of this invention is to provide silylated
organic-organopolysiloxane block copolymers. Still another object of this
invention is to provide a method for preparing silylated organic polymers.
A further object of this invention is to provide a method for preparing
silylated organic-organopolysiloxane block copolymers.
These and other objects which will become apparent from the following
description are accomplished in accordance with this invention, generally
speaking, by reacting (A) alkali metal terminated organic polymers with
(B) silanes containing aliphatic unsaturation in the presence of an
aprotic solvent to produce silylated organic polymers of the formula
##STR1##
where M is an alkali metal, Y is the organic polymer and the unsatisfied
valences of the silicon atom are satisfied by a hydrocarbon radical or Y.
These silylated organic polymers described above may be further reacted
with other silanes containing aliphatic unsaturation or with unsaturated
monomers capable of anionic polymerization to form block copolymers of
silylated organic polymers. These silylated organic polymers or block
copolymers are reacted with cyclic siloxanes to form silylated
organic-organopolysiloxane block copolymers.
More specifically, these polymers may be prepared by reacting a carbanion
producing catalyst with unsaturated monomers in the presence of an aprotic
solvent. Examples of suitable carbanion producing catalysts are alkali
metals such as lithium, sodium, potassium, rubidium, cesium and
organoalkali metal compounds such as lithium naphthalene, lithium
anthracene, butyl lithium, vinyl lithium, lithium stilbene, biphenyl
lithium, 1,4-dilithiobenzene, 1,5-dilithiopentane,
1,5-dilithionaphthalene, 1,2-dilithio-1,3,3-triphenylpropane,
1,3,5-trilithiopentane, sodium naphthalene, notassium naphthalene,
rubidium naphthalene, cesium naphthalene, sodium anthracene, potassium
anthracene, rubidium anthracene, cesium anthracene, sodium stilbene,
potassium stilbene, rubidium stilbene, cesium stilbene, 9-fluorenyl
sodium, 9-fluorenyl potassium, 9-fluorenyl cesium, diphenyl sodium,
diphenyl potassium, diphenyl rubidium, diphenyl cesium and the like.
monalkylene
The term "aprotic solvent" refers to any organic solvent which is free of
active protons. These may include hydrocarbon solvents such as heptane,
benzene, toluene and xylene and the like. It is preferred but not
necessary that an aprotic solvent capable of coordinating with the alkali
metal be employed. These include nonacid oxygen containing and nitrogen
containing organic solvents such as tetrahydrofuran, tetrahydropyrane,
diethoxyethane; alkyl ethers such as diethyl ether, dibutyl ether, methyl
ethyl ether; higher boiling ethers such as monoalkylene glycol dialkyl
ethers, dialkylene glycol monoalkyl ethers, dialkylene glycol dialkyl
ethers and monoal kylene glycol monoalkyl ethers, dimethyl acetamide,
N-methylpyrrolidine, isobutylene oxide, dimethyl sulfoxide, dioxane,
diethyl ether of diethylene glycol, and various tertiary amines such as
dimethyl aniline, tributylamine, pyridine and the like. For obvious
reasons, solvents which contain an acid hydrogen should be avoided.
Any unsaturated monomer that may be polymerized by anionic polymerization
techniques may be employed in this invention. Also, any polymerized
substituted olefin having C. unsaturation is operative in this invention.
Specific examples of suitable monomers are hydrocarbon olefins such as
ethylene, butadiene, styrene, vinyltoluene, divinylbenzene, isoprene,
unsaturated esters such as the acrylates and alkyl substituted acrylates,
e.g., methylacrylate, methylmethacrylate, ethylacrylate, butylacrylate and
unsaturated nitriles such as acrylonitrile, methacrylonitrile and the
like.
The reaction between the carbanion forming catalyst and the unsaturated
organic polymers may be conducted at any temperature below 150.degree. C.
preferably below about 100.degree. C. and more preferably between about
0.degree. C. and 50.degree. C.
The alkali metal terminated organic polymers thus formed may be reacted
with silicon compounds containing aliphatic unsaturation. These silicon
compounds may be represented by the general formula
##STR2##
where R is a monovalent hydrocarbon radical, X is a member selected from
the class consisting of halogen, hydrocarbonoxy radicals, acyloxy
radicals, phosphato radicals, sulfato radicals, perchlorate radicals, or
any other groups which are reactive with the alkalimetal carbanion, a is a
number of from 1 to 4 and b is a number of from 1 to 3.
Suitable examples of radicals represented by X are halogens such as
chlorine, fluorine, bromine and iodine; acyloxy radicals of the formula
##STR3##
in which R' is hydrogen or an organic radical such as an alkyl or aryl
radical having from 1 to 18 carbon atoms; hydrocarbonoxy radicals of the
formula -OR" in which R" is an organic radical such as alkyl or aryl
radicals of from 1 to 10 carbon atoms; phosphato radicals of the formula
##STR4##
in which R' is the same as above; sulfur containing radicals of the
formula SO.sub.y where y is an integer of from 2 to 4 and chlorates of the
formula -C10.sub.4.
Suitable examples of alkyl radicals represented by R are methyl, ethyl,
propyl, butyl, pentyl, hexyl, octyl, decyl, octadecyl and the like; aryl
radicals such as phenyl, naphthyl, biphenyl and the like; alkaryl radicals
such as tolyl, xylyl, ethylphenyl and the like; aralkyl radicals such as
benzyl, phenylethyl and the like. The organic radicals represented by R'
and R" may be the same as the alkyl and aryl radicals represented by R.
Examples of suitable silanes having aliphatic unsaturation which may be
employed in the preparation of the silylated organic polymers are
vinyltrichlorosilane, divinyldichlorosilane, divinyldiacetoxysilane,
dimethoxymethylvinylsilane, methylvinyldiacetoxysilane,
dimethylvinylbromosilane, trimethylvinylsilane, tributylvinylsilane,
phenylmethylvinylchlorosilane, dibutylvinylacetoxysilane and the like.
The reaction between the alkali metal terminated organic polymers and the
silanes containing aliphatic unsaturation may be carried out in the
presence or absence of a solvent. It is oreferred that the reaction be
conducted in the presence of aprotic solvents which are capable of
coordinating with the alkali-metal cation. Surprisingly, it has been found
that when such solvents are employed, the alkali-metal carbanion
preferably reacts with the halogen or other reactive groups before it
reacts with the C.dbd.C unsaturated group, thus permitting a greater
degree of control of molecular weight and chain branching. The aprotic
solvents employed may be the same as those described heretofore. Although
the amount of solvent is not critical, it is preferred that from 1 to 95
percent by weight of solvent be presented based on the weight of the
alkali metal organic polymers and unsaturated silanes.
Generally, the reaction is carried out at a temperature of from about
0.degree. to 150.degree. C. And more preferably from about 10.degree. to
50.degree. C. Higher or lower temperatures may however be employed, if
desired.
The preparation of the alkali metal terminated organic polymers may be
illustrated by the following equations, although these are not intended to
limit the scope of the invention.
##STR5##
The reaction between the resulting organometallic hydrocarbon compound of
equation (1) and the silane containing an unsaturation aliphatic group may
be illustrated in the following manner.
When the polystyryllithium compound is reacted with, for example,
vinyltrichlorosilane, a branched silicon-hydrocarbon polymer is formed.
##STR6##
When the polystyryllithium compound is reacted with for example, a
trimethylvinylsilane, as illustrated below a linear silicon hydrocarbon
polymer is formed.
##STR7##
In accordance with the invention the hydrocarbonsilylethyl-1-alkali-metal
can be reacted with a cycli organopolysiloxane to form block copolymers
containing silicon-hydrocarbon segments and organopolysiloxane segments.
Cyclic organopolysiloxanes which can be used in the method of this
invention include those of the formula (R.sub.2 SiO).sub.n in which n is
at least 3 and may be up to 10 in which R is the same as above. the
reaction is preferably carried out in the presence of an aprotic solvent
and more preferably in the presence of an aprotic solvent which is capable
of coordinating with the catalyst. The same aprotic solvents as described
above may be employed in this reaction. In carrying out the reaction, the
reaction temperature is not critical and may range from 25.degree. C. to
about 200.degree. C. and more preferably from about 25.degree. C. to
150.degree. C. However, higher or lower temperatures may be employed, if
desired.
Suitable examples of cyclic organopolysiloxanes which may be employed in
the reaction are hexamethylcylotrisiloxane, 1,3,5,-trimethyl
-1,3,5-triphenylcyclotrisiloxane, octamethylcyclotetrasiloxane,
octaphenylcyclotetrasiloxane, decamethylcyclopentasiloxane,
pentamethylpentaphenylcyclopentasiloxane, hexadecamethycycloctasiloxane
and the like.
The reaction between the alkali metal silylated hydrocarbon polymers and
hexamethylcyclotrisiloxane (D.sub.3) may be illustrated by the following
equations.
##STR8##
The hydrocarbon-silylethyl -1-alkali metal can be further reacted with
other monomers containing other olefinic unsaturation and/or other vinyl
containing silanes to form silylated hydrocarbon polymers having multiple
branched or linear chains of repeating units. The resulting silylated
hydrocarbon polymers described above can then be reacted with cyclic
organopolysiloxanes such as described above to form silylated hydrocarbon
organopolysiloxane block copolymers in which the silylated hydrocarbon
polymers contain multiple branched or linear chains. The following
equations illustrate the general reactions, but are not intended to limit
the scope of this invention.
##STR9##
The silylated organic polymers and the copolymers consisting of silylated
organic polymers and organopolysiloxanes which contain the metal carbanion
or metal silanolate, respectively, may be reacted with various compounds
to remove the reactive sites in the polymer. Examples of suitable
compounds are water; carboxylic acids such as acetic acid, oxalic acid,
formic acid, maleic acid and the like; carboxylic acid anhydrides such as
acetic anhydride, phthalic anhydride, maleic anhydride and the like;
inorganic acids such as hydrochloric, hydroiodic, hydrofluoric,
hydrobromic, sulfuric, nitric, perchloric and the like; alcohols such as
methanol, ethanol, isopropanol, 1-butanol and the like; silanes which have
at least one functional group selected from the class consisting of
halogen, acyloxy, phosphato, sulfato, hydrocarbonoxy and perchlorato
radicals such as trimethylchlorosilane, dimethyldichlorosilane,
methyltrichlorosilane, silicon tetrachloride, trimethylacetoxysilane,
dimethyl disulfato silane, methyltrimethoxysilane, methyltris
(diethylphosphato) silane and the like.
The silylated organic polymers and silylated organic-organopolysiloxane
copolymers may be vulcanized by the conventional techniques known in the
art. For example, when polydiene units are present, vulcanization is
possible with sulfur as well as with other chemicals which have been used
for curing natural rubber. Other vulcanization agents which may be used in
place of sulfur are disulfides, alkyl phenol sulfides, p-dinitrosobenzene,
sulfur dichloride, tetramethyl thiuram disulfide, tetraethyl thuran
disulfide, etc. Any conventional process known to the art may be employed
in the vulcanization of the above polymers such as by milling and heating
in the presence of vulcanizing agents.
The silylated organic polymers and silylated organic-organopolysiloxane
block copolymers obtained from vinyl monomers can be cured using the
conventional curing agents employed in heat curable organopolysiloxane
compositions. Examples of suitable curing agents are organic peroxides
such as dicumyl peroxide, benzoyl peroxide, bis(2,4-dichlorobenzoyl)
peroxide, tertiary butyl perbenzoate, high energy radiation and the like.
Moreover, these polymers may be combined with various silane or siloxane
cross-linking agents known in the art to form room temperature or heat
vulcanizable compositions. Examples of suitable cross-linking agents are
silanes and siloxanes containing acyloxy groups having up to 10 carbon
atoms such as methyltriacetoxysilane, tetraacetoxysilane and the like;
silanes and siloxanes containing aryloxy or alkoxy groups such as
tetraethylorthosilicate, ethyl silicate "40"; silanes containing amino
groups such as methyltricyclohexyl aminosilane, hydrogen containing
silanes such as methylhydrogenpolysiloxanes and the like. Other
cross-linking agents which may be employed are silanes or siloxanes
containing other groups which are hydrolyzable at room temperature such as
oximo groups, aminooxy groups, amides and phosphato groups. Compounds such
as titanates, tin salts of carboxylic acids and platinum compounds may be
employed as catalysts to accelerate the curing of these compositions.
Also, temperatures of from 25.degree. C. may be used to accelerate curing.
These polymers and copolymers may be compounded with various additives,
depending on the particular properties desired, before they are cured.
Suitable examples of these additives are stabilizers, plasticizers,
fillers preferred the like.
The block copolymers obtained herein, especially in the cured state can be
employed in the manufacture of high temperature sealants, e.g., as
gaskets, rings, tubing, fuel lines, insulation, motor mountings and the
like.
The embodiments of this invention are further illustrated by the following
examples in which all parts are by weight unless otherwise specified.
EXAMPLE I
Approximately 6 parts of a 1.5 molar solution of n-butyl lithium (0.01
mole) in heptane and 15 parts of tetrahydrofuran are added to a round
bottom flask equipped with a stirrer. A nitrogen atmosphere is maintained
in the flask. The mixture is cooled to 0.degree. C. and 9.6 parts of
tertiary-butyl styrene are added dropwise. The reaction mixture is stirred
0.5 hour at room temperature and then the reaction mixture is cooled to
0.degree. C. About 0.46 part of methylvinyldichlorosilane is added
dropwise to the reaction mixture. The temperature is maintained at
0.degree. to 10.degree. C. throughout the addition. The reaction mixture
is stirred 1 hour at room temperature, then 0.06 part of acetic acid is
added and the lithium acetate precipitate thus formed is removed by
filtration. The silylated hydrocarbon polymer is isolated from the solvent
by vacuum stripping. Analysis of the product indicates that it has the
following structure.
##STR10##
The molecular weight of the product is about 2900. The theoretical value
calculated is about 3148. This illustrates that silylated hydrocarbon
polymers may be prepared having a predetermined amount of branching and a
predetermined molecular weight.
EXAMPLE II
The procedure of Example I is repeated except that 9-fluorenyl sodium is
substituted in the same mole ratio for the n-butyl lithium. Essentially
the same results are obtained.
EXAMPLE III
About 109.8 parts of a 1.5 molar solution of n-butyl lithium (1.18 moles)
in heptane and 75 parts of tetrahydrofuran are added to a round bottom
flask equipped with a stirrer. A nitrogen atmosphere is maintained in the
flask. The mixture is cooled to 0.degree. C. and 76.2 parts of styrene are
added over a twenty minute period. The temperature throughout the addition
is maintained at 0.degree. to 10.degree. C. The reaction mixture is
stirred one hour at room temperature, then 8.6 parts of
methylvinyldichlorosilane is added over a one minute period and the
resulting reaction mixture is stirred for an additional hour at room
temperature. The resulting silylated hydrocarbon polymer may be
represented by the general formula
##STR11##
About 108.3 parts of hexamethylcyclotrisiloxane and 110 parts of benzene
are added to the reaction mixture. The mixutre is refluxed for about 4.5
hours, then about 5 parts of acetic acid are added and the lithium acetate
precipitate thus formed is removed by filtration. The silylated
polystyryl-dimethylpolysiloxane copolymer is isolated by vacuum stripping.
A grease-like composition is obtained which may be represented by the
general formula
##STR12##
Nuclear Magnetic Resonance analysis confirms the ratio of siloxane to
polystyrene of 1:0.48. Molecular weight analysis indicates a molecular
weight of about 3390. The theoretical value calculated for this product is
approximately 3262. This example demonstrates that silylated
hydrocarbon-organopolysiloxane copolymers may be prepared having a
predetermined number of silylated hydrocarbon units and organopolysiloxane
units.
EXAMPLE IV
The procedure of Example III is repeated except that an equal molar amount
of 9-fluorenyl potassium is substituted for the n-butyl lithium. A
silylated polystyrene-dimethylpolysiloxane copolymer having a lower
molecular weight than the copolymer prepared in Example III is obtained.
EXAMPLE V
The procedure of Example III is repeated except that 7.8 parts of
dimethyldichlorosilane are substituted for the methylvinyldichlorosilane.
The resulting product is a heterogeneous material containing a solid and
liquid phase. Analysis of the solid phase indicates a composition of the
general formula
##STR13##
The liquid phase appears to be a product of the general formula
##STR14##
This example further illustrates that copolymers are formed when
vinylfunctional silanes are employed.
EXAMPLE VI
The procedure of Example III is repeated except that 5.86 parts of
methyltrivinylsilane are substituted for methylvinyldichlorosilane. The
resulting product is represented by the general formula
##STR15##
EXAMPLE VII
The procedure of Example III is repeated except that 49.6 parts of isoprene
are substituted for the styrene. A silylated
polyisoprene-organopolysiloxane copolymer is identified.
EXAMPLE VIII
The procedure of Example IV is repeated except that 108.3 parts of
octamethylcyclotetrasiloxane are substituted for the
hexamethylcyclotrisiloxane. Substantially the same results are obtained as
in Example IV. This example shows that any cyclic organopolysiloxane may
be used in the preparation of copolymers of this invention.
EXAMPLE IX
The product obtained from Example VI (100 parts) is mixed with 5 parts of
methyltriacetoxysilane in a nitrogen atmosphere and then exposed to
atmospheric moisture. After about 20 hours, an insoluble rubber-like
material is obtained.
Although specific examples of the invention have been described herein, it
is not intended to limit the invention solely thereto, but to include all
the variations and modifications falling within the spirit and scope of
the appended claims.
* * * * *
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