Note: Descriptions are shown in the official language in which they were submitted.
~57~7
ORGANOSILOXANE-OXYALKYLENE COPOLYMERS
This invention relates to copolymers comprising
organosiloxane units and oxyalkylene units, and also re-
lates to a process ~or preparing such copolymers.
Copolymers comprising siloxane units and oxyalkylene
units are now well known and have been commercially
employed in applications such as surfactants for polyure-
thane foams and as textile fibre lubricants. In U.K.
Patent 1 29C 687 there are disclosed siloxane-polyoxyalk-
ylene block copolymers in which there are present methoxy
groups attached to silicon atoms. It is stated in the
said patent that a preferred application of the block co-
polymers is in the treatment of hydrophobic fibres to
improve their soil resistance. European Patent Applica-
tion 32 310 also discloses copolymers containing siloxane
units, oxyalkylene units and silicon-bonded hydrolysable
groups, and the use of such cGpolymers for treating
textiles. In the above described prior art copolymers
the methoxy groups or hydrolysable groups are attached to
a silicon atom in the siloxane chain either directly or
by way of an aliphatic hydrocarbon linkage.
According to the present invention there are pro-
vided organosiloxane-oxyalkylene copolymers wherein at
least one silicon atom of an organosiloxane unit has
attached thereto a group represented by the general
2~ formula
z
-X(OR)nOsiR a(OR )2-a
wherein X represents a divalent hydrocarbon group having
from 2 to 8 carbon atoms, R represents an alkylene group
having from 2 to 4 carbon atoms, n is an integer of at
least 2, Z represents an organic group composed of
7~7
-- 3 --
carbon, hydrogen and oxygen and having therein at least
one epoxy group, R' represents a lower alkyl, vinyl or
phenyl group, R" represents an alkyl or an alkoxyalkyl
group having less than 7 carbon atoms and a has a value
of 0 or 1, the remaining silicon-bonded substituents in
the organosiloxane units being selecte~ from hydrogen
atoms, monovalent hydrocarbon groups and groups represen-
ted by the general formula
-X(OR)nOG
wherein X and R are as hereinabove defined and G repres-
ents a hydrogen atom, a monovalent hydrocarbon group
having from 1 to 10 carbon atoms or an acyl group having
from 2 to 6 carbon atoms, at least 40 percent of the
total substituents bonded to siloxane silicon atoms in
the copolymer being methyl.
In the general formula above ~(OR)n~ represents an
oxyalkylene block having at least 2, preferabl~ from 2 to
50 oxyalkylene units OR. The oxyalkylene units are pref-
erably oxyethylene or oxypropylene or combinations of the
two, for example -(OC2H4)6(OC3H6)6-. The group X which
links the oxyalkylene block to the siloxane silicon atom
may have from 2 to 8 carbons, but, in view of the more
ready availability of the polyoxyalkylene precursor, is
preferably the propylene group -(CH2)3.
The substituent Z is an epoxidised monovalent
organic group composed of carbon, hydrogen and oxygen.
o
Examples of such groups include the group -CH2CH
and those represented by the general formula
/ O\
-QCH - CH2
wherein Q represents a divalent hydrocarbon group e.g.
ethylene, butylene, phenylene, cyclohexylene and
~2
- 4 -
-CH2C~ ~ or an ether oxygen-containing group such
as -CH2C~12OCH2CH2 and -CH2C~2OC~(CH3)CH2-. Pr~ferably Z
,,~ O~
represents the group -(CH2)3OCH2CH - CH2.
S As the R" groups there may be present any alkyl or
alkoxyalkyl group havlng less than 7 carbon atoms e.g.
methyl, ethyl, propyl, methoxyethyl and ethoxyethyl, the
preferred copolymers being those wherein R" represents
methyl, ethyl or methoxyethyl. The R' groups, when pre-
sent, may be Cl 4 alkyl, vinyl or phenyl.
At least one of the above oxyalkylene containing
groups should be present in the copolymer. The number
present in any particular case will depend upon such
factors as the size of the copolymer molecule desired and
the balance sought between the properties bestowed by the
siloxane and oxyalkylene portions. The remaining substi-
tuents on the siloxane silicon atoms may be selected from
hydrogen atoms, monovalent hydrocarbon groups e.g. ethyl,
propyl, 2,4,4-trimethylpentyl, vinyl, allyl and phenyl
and silicon-free oxyalkylene groups of the formula
-X(OR)nOG, wherein G is for example ethyl, butyl or
acetyl; with the proviso that at least 40 percent of the
total siloxane silicon-bonded substituents are methyl
groups. The preferred copolymers of this invention are
those wherein the oxyalkylene groups (OR)n are oxyethyl-
ene and comprise at least 35% of the total weight of the
copolymer.
The copolymers of this invention may take any of
the molecular configurations available to such copolymers
provided such configuration is consistent with the pres-
ence of terminal silyl groups on the oxyalkylene-contain-
ing group or groups. For example, they may be of the ABA
configuration wherein A represents the
_ 5 _ ~2 ~ 57 6'~
-X(~R)nosiR a(OR )2-a
group and B represents a linear sîloxane portion e.g.
-(M2SiO)b wherein each M individually represents an
organic substi~uent such as -CH3 and b is an. integer of
at least 2. Alternatively the copolymer may be of the
so-called "rake" configuration wherein the oxyalkylene-
containing groups are pendant from a siloxane chain as in
M IM M M
MSiO--- - SiO- _ -SiO- - SiM
M M A M
Y z
in which y is zero or an integer and z is an integer.
According to yet another configuration the oxyalkylene-
containing (A) groups may be present both in the pendantpositions and attached to the terminal silicon atoms of
the siloxane chain. It will thus be apparent that in
addition to the siloxane units having oxyalkylene groups
attached thereto the copolymers of this invention may
also comprise monofunctional M3SiO~ units, difunctional
M2SiO and trifunctional MSiO3/2 units. If desired, small
proportions of tetrafunctional SiO2 units may also be
present.
The copolymers of this invention can be obtained by
reacting together (A) an organosiloxane-oxyalkylet~e
copolymer wherein at least one silicon atom of an organo-
siloxane unit has attached thereto a group of the general
formula
-X(OR)nOH
the remaining silicon-bonded substituents in the organo-
siloxane units being selected from hydrogen atoms, mono-
valent hydrocarbon groups and groups represented by the
general formula -X(OR)nOG, at least ~0 percent of the
- 6 ~22~i7Ej7
total substituents bonded to siloxane silicon atoms in
the copolymer being methyl groups, and (B) an organo-
silane
ZSiR'a(OR )3-a
wherein X, R, ~, R', R" and a are as hereinbefore defined
and G represents a monovalent hydrocarbon group having
from 1 to 10 carbon atoms or an acyl g:roup having from 2
to 6 carbon atoms.
Organosiloxane-oxyalkylene copolymers (A) employed
in the said preparative process are a known class of
materials. Such copolymers and methods for their prepa~
ration are described in, for example, British Patents
~02 467 and 1 ll~3 206, The silanes (B) are also known
substances and have been disclosed in, for example,
British Patent 83~ 326.
Some reaction between (A) and (B) to form the
organosiloxane-oxyalkylene copolymers of this invention
is believed to occur at normal ambient temperatures. It
is preferred, however, to expedite the reaction by the
use of higher temperatures, for example, from about 60C
to 180C. If desired the reaction may be carried forward
in the presence of a transesterification catalyst, for
example zinc tetrafluoroborate, an organic tin compound
e.g. stannous octoate or a titanium compound e.g. tetra-
2S butyl titanate. Where subsequent reaction of thecopolymer via the epoxy groups is envisaged the preferred
catalysts are those which also function to open the epoxy
ring e.g. zinc tetrafluoroborate.
The relative molar proportions of the reactants
employed may be varied to achieve substantially complete
reaction of the available COH groups, or to induce only
partial reaction whereby the resulting copolymer product
contains both silylated and non-silylated oxyalkylene
groups.
~ ~257~7
-- 7 --
The molecular weight of the copolymers of this
invention may vary widely and the copolymers may range
from mobile liquids to gummy or waxy solids. When a
sufficient proportion of oxyethylene units is present the
copolymers are water-soluble. The copolymers may there-
fore be formed into curable films on continuous, porous
or fibrous substrates from aqueous or non aqueous
solutions. Curing of the copolymers into films will take
place in the absence of a curing catalyst. It is, how-
ever, generally preferred to accelerate the cure by theaddition of a siloxane condensation catalyst. A wide
variety of such catalysts are known and include, for
example acids, bases and metal organic compounds such as
the ~etal carboxylates e.g. dibutyltin dilaurate,
stannous octoate and zinc octoate and titanium alkoxides
and chelates. Certain substances e.g. zinc tetrafluoro-
borate and stannous octoate can function both as a trans-
esterification catalyst during the preparation of the
siloxane-oxyalkylene copolymer and subsequently as a
curing catalyst therefor.
It is also preferred to effect drying and curing
of the films at elevated temperatures. The actual temp-
erature employed will depend to some extent on the nature
and heat resistance of the substrate, temperatures in the
range from about 80C to about 180C being generally
appropriate.
If desired the copolymers of the invention may be
mixed with fillers, pigments and other additives to
produce compositions curable to rubbery solids having
paintable surfaces.
The following examples in which Me represents
methyl illustrate the invention.
- 8 - ~2 ~ 7
Example 1
To a 20 litre split-necked flask equipped with a
stirrer, condenser and thermometer was charged 12,500g of
a siloxane-oxyalkylene copolymer of average composition
E (CH2C~2)12(cH2)3siMe2Oo 5¦ 2 (SiMe2O)14. The flask
was heated to 9QC and a 40~-by weight aqueous solution
(26ml) of zinc tetrafluoroborate added and dissolved with
stirring. This was follow~d by the addition over 2
minutes of the silane.
/\
(MeO)3Si(CH2)3OCH2CH - CH2 (2458.7g), the reaction
mixture then being maintained at 90C for a further 2
hours. On cooling there was obtained 14,870g (99.5%) of
a clear, amber, water-soluble liquid.
When an aqueous solution (15% by weight) of the
liquid was coated Oll to aluminium and dried at 150C for
3 minutes a cro~slinked, water-insoluble, hydrophilic
film was obtained.
Example 2
192G of the siloxane-oxyalkylene copolymer employed
in Example 1 and lgm of concentrated hydrochloric acid
were heated with stirring to 90C. 37.8G of the silane
/ O\
(MeO)3SiCH2CH2CH2oCH2CH C~l2
were added and the mixture maintained at 90C for 2
hours. On cooling there was obtained 223g (97%) of a
clear, amber, water-soluble liquid. When an aqueous sol-
ution (15% by weight) of the liquid was coated onto alum-
inium and dried for 3 minutes at 150C a crosslinked 25
water insoluble film was obtained.
Example 3
Employing the procedure of Example 1 a siloxane-
oxyalkylene copolymer (240g) of average composition
~5~6~7
g
Me3Si(OSiMe2)9tOSiMe)30SiMe3
(CH2)3(OcH2cH2)l2
and the silane
/o\
(MeO)3Si(CH2)3OCH2CH - CH2 ~70.8g) were
reacted at 90 - 100C in the presence of a 40% by weight
aqueous solution (3ml) of zinc tetrafluoroborate.
The reaction product (304g) was a clear, amber-
coloured liquid which formed clear aqueous solutions. On
drying these solutions (10% by weight) at 150C for 3
minutes clear crosslinked hydrophilic films were
obtained.
Example 4
150.9G of a siloxane-oxyalkylene copolymer having
the average composition
EO(CH2CH20)7 s(C~12)3siMe20.~ 2 ( 2 l~.5
was heated to 80C with stirring. A 40% by weight
aqueous solution (2ml) of Zn(BF4)2 was then added,
~ollowed by 117 . 2g of the silane
/\
(MeO)3Si(CH2)30CH2-CH-CH2
The mixture was maintained at 80C for 2 hours and
then allowed to cool. A slightly ha~y water-soluble
liquid was obtained. When a 10% by weigh~ aqueous
solution of this liquid was dried at 150C a crosslinked,
water-insoluble film resulted.
