Note: Descriptions are shown in the official language in which they were submitted.
~7~7~;~
"Crosslinked Silicone-Vinyl Polymer Systems"
The invention relates to stable co-grafted poly-
mer dispersions which can be cured at room temperature
and comprise organopolysiloxanes containing terminal
.OH functional groups and, if appropriate, other polydi-
organosiloxanes, and ethylene/vinyl ester copolymers and
vinyl polymers, a process for their preparation and the
use of these co-grafted polymer dispersions.
Polymer systems which are based on organopoly-
siloxanes and can be cured at room temperature are known
(compare, for example, W. Noll, Chemie und Technologie
der Silikone (Chemistry and Technology of the Silicones),
Verlag Chemie GmbH, 1968, page 391 et seq.).
Furthermore, it is possible, and known, to prepare
modified organopolysiloxanes by various procedures.
Grafted polymers of organosiloxanes and vinyl polymers
are described, for example, in British Patent Specifica-
tions 766,528, 806,582 and 869,482 and DE-AS (German Pub-
20 lished Specification) 1,694,973. The use of organopoly-
siloxanes with an organic chain grafted on and at most
25% of aryl radicals in l- or 2-component compositions
which cure at room temperature is described in DE-AS
(German Published Specification) 1,694,973. It is sta-
25 ted that the hydroxypolysiloxanes employed according tothat invention contain in each case up to at most 25% of
aryl radicals.
^ It is also stated that the organic chain grafted
on is formed by polymerized units of vinyl monomers, pre-
30 ferably styrene and acrylates.
Mixtures of a non-silicone polymer, for example a
polyolefin, olefin copolymers, such as ethylene/alkyl
acrylate or ethylene/vinyl ester copolymers, and a mo~-
organopolysiloxane resin are also known (DT-OS (German
35 Published Specification) 2,832,893). These polymer com-
~e r~ 20 5~)8
.. ~
117~7~3Z
positions which are described in ~T-OS (German Published
Specification) 2,832,893 can be processed from the melt
and are used for coating, for example,~wires and have a
low oxygen index, but they cannot be used as sealing com-
positions which cure at room temperature as a result ofmoisture in the environment.
The use of block or graft copolymers of 5-95% by
weight of a polydiorganosiloxane and 5-95% by weight of a
homopolymeric or copolymeric vinyl thermoplatic, as a
10 homogenizing agent, for the preparation of a homogeneous
mixture of a polydiorganosiloxane and a vinyl thermoplas-
tic is described in DT-AS (German Published Specification)
2,142,597, the vinyl thermoplastic mentioned being pre-
sent in an amount of at least 40% by weight, relative to
the total weight of the mixture. The preparation of the
graft copolymers is always carried out with the aid of
polyorganosiloxanes with reactive groups which react with
the free radicals of the polymerization system. Examples
of such reactive groups are silicon-bonded vinyl or 3-
mercaptopropyl groups. One route for the production ofthe mixtures of vinyl thermoplastic and polydiorganosil-
oxane consists in dissolving the polydiorganosiloxane and,
for example, the graft copolymer in a vinyl monomer and
then polymerizing the vinyl monomer. The resulting
uniform dispersionsof polyorganosiloxanes in the vinyl
thermoplastics imparts improved processing properties to
the vinyl thermoplastic. Use of these mixtures for
elastomeric silicone compositions which are obtained by
curing with atmospheric moisture at room temperature is
not mentioned, and could furthermore not take place with
such systems.
Ethylene/vinyl acetate copolymers are industrially
important thermoplastics and elastomers. A particularly
outstanding characteristic of these copolymers is their
excellent resistance to aging, even at elevated tempera-
Le A 20 508
~1747E~2
-- 3
tures. ~ixtures of polydiorganosiloxanes and ethylene/vinyl acetate copolymers are unstable, since the starting
polymers are completely incompatible. . Although it would
be desirable to combine the excellent use properties of
ethylene/vinyl acetate copolymers with those of silicone
elastomers, this has as yet not been achieved in an in-
dustrially satisfactory manner.
T'ne object of the invention is thus to provide
multi-phase systems of organopolysiloxanes and ethylene/
vinyl acetate copolymers, the phases of which are stable.
~ nother object of the invention is to provide
silicone compositions which, if appropriate after the
addition of plasticizers,such as, for example, organo-
polysiloxanes with methyl e~d groups, fillers, cross-
linking agents, crosslinking catalysts and components
which accelerate crosslinking, and after crosslinking at
room temperature in a manner which is in itself known,
can be lacquered in a better manner and have an improved
adhesion to various substrates.
Both objects have been achieved by subjecting mix-
tures of organopolysiloxanes, ethylene/vinyl ester copoly-
mers and vinyl monomers to free radical polymerization in
the presence of agents which form free radicals. Stable
dispersions which consist of an ethylene/vinyl ester co-
polymer component, an organopolysiloxane and polymerized
units of one or more vinyl monomers and which contain
graft copolymers, crosslinked via polymerized units of
the vinyl monomers employed, of the organopolysiloxane
and the ethylene/vinyl ester copolymer employed are ob-
tained.
The invention thus relates to co-grafted po]ymer
dispersions, characterized in that they contain organo-
polysiloxanes with OH functional groups and, if appro-
priate, other polydiorganosiloxanes, and ethylene/vinyl
ester ccpolymers ccntaining abcut 5 to 39% by weight of incor-
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~1179c7~;~
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porated vinyl ester, vinyl monomer units ~olymerize~in the presence of mixtures of these organopolysiloxanes
and ethylene/vinyl ester copolymers, and organopoly-
siloxane and ethylene/vinyl ester copolymer components
linked via vinyl polymer bridges.
The invention relates to co-grafted polymer dis-
persions co~prising a~out I. 1 b-90% by weight of organo-
polysiloxanes with terminal OH functional groups, II.
0-40% by weight of organopolysiloxanes with trimethyl-
silyl end groups, III. 5-85% by weight of ethylene/
vinyl ester copolymers containing 5-99% by weight of
incorporated vinyl ester, and IV. 5-85% by weight of
~ olyiæ~ized units of vinyl compounds, the sum of compon-
ents I-IV always being 100%.
The invention also relates to co-grafted polymer
dispersions comprising about I. 10-90% by weight of organo-
polysiloxanes containing terminal OH functional groups,
II. 0-40% by weight of organopolysiloxanes with tri-
methylsilyl end groups, III. 5-85% by weight of ethy-
20 lene/vinyl acetate copolymers containing 5-99% by weight
of incorporated vinyl acetate, and IV. 5-85% by weight
of ~olymerized units of vinyl esters, ~,~-unsaturated
carboxylic acids, derivatives of ~,~-unsaturated mono-
or di-carboxylic acids, vinyl-aromatic compounds, such -
25 as styrene, ~-methylstyrene or 4-chlorostyrene, ~-ole-
fins, such as ethylene, propylene, l-butene or isobut-
ylene, halogenated vinyl monomers, such as vinyl chlor-
ide, vinylidene chloride, vinyl fluoride, vinylidene
fluoride, tetrafluoroethylene or trifluorochloroethylene,
30 vinyl ethers, such as ethylene vinyl ether or n-butyl
vinyl ether, allyl compounds, such as allyl alcohol,
allyl acetate, allyl carbonates, diallyl carbonate or di-
allyl phthalate, divinyl compounds, such as divinylben-
zene or divinyl ethers, or (meth)acrylic acid esters of
35 polyhydric alcohols, or mixtures of these monomers, the
.
Le A 20 508
~L7~78Z
-- 5 --
sum of components I-IV always being 100%.
The invention also relates to co-grafted polymer
dispersions comprising about I. 10-90%~by weight of organo-
polysiloxanes containing terminal OH functional groups,
II. 0-40% by weight of organo-polysiloxanes with tri-
methylsilyl end groups, III. .5-85% by weight of ethylene/
vinyl acetate copolymers containing 25-75% by weight of
incorporated vinyl acetate, IV. 5-85% by weight of poly-
merized vinyl acetate units, and V. 0-80% by weight of
10 polymerized units of (meth)acrylic acid Cl-C8-alkyl est-
ers, (meth)acrylamide, N-alkyl-substituted (meth)acryl-
amides, (meth)acrylonitrile and mixtures thereof, the sum
of the components always being 100%.
The invention also relates to co-grafted polymer
dispersions comprising about I. 10-90% by weight of organo-
polysiloxanes containing terminal OH functional groups,
II. 0-40% by weight of organopolysiloxanes with tri-
methylsilyl end groups, III. 5-85% by weight of ethy-
lene/vinyl acetate copolymers containing 25-75% by weight
of incorporated vinyl acetate, and IV. 5-85% by weight
of polymerized units of a) 0-90% by weight of styrene, b)
10-100% by weight of (meth)acrylic acid Cl-C8-alkyl est-
ers and c) 0-90% by weight of (meth)acrylonitrile, the
sum of components IVa to IVc always being 100% and the .
sum of components I-IV likewise always being 100%.
The co-grafted polymer dispersions according to
the invention prefera~ly comprise about I. 33-90~ by weight
of organopolysiloxanes containing terminal OH functional
groups, II. 0-40% by weight of organopolysiloxanes with
trimethylsilyl end groups, III. 5-65% by weight of ethy-
lene/vinyl acetate copolymers containing 25-75% by weight
of incorporated vinyl acetate, and IV. 5-65% by weight
of polymerized vinyl acetate units.
The invention also relates to a process for the
preparation of co-grafted polymer dispersions, character-
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-- 6 --ized in that m~xtures of about I. 8-90% by weig.~t of organ~ -
polysiloxanes containing terminal OH functional groups,
II. 0-40% by weight of organopolysiloxanes with tri-
methylsilyl end groups~, III. 4.999-85% by weight of
ethylene/vinyl ester copolymers containing 5-99% by
weight of incorporated vinyl esters, I~. 5-85% by weight
of one or more vinyl monomers and ~. 0.001-2% by weight
of one or more agents which form free radicals, the sum
of components I- V always being 100%, are subjected to a
lO polymerization reaction, if appropriate in the presence
of chain-transfer substances or molecular weight regulat-
ors, at temperatures between room temperature and +250C
and under pressures between 100 mm Hg and 500 bars.
The invention furthermore relates to organopoly-
siloxane compositions which can be crosslinked at roomtemperature and contain the co-grafted polymer dispersions
and, in addition, crosslinking agents, curing catalysts,
fillers, and, if appropriate, further additives.
The invention also relates to the use of organo-
20 polysiloxane compositions which can be crosslinked atroom temperature and contain the co-grafted polymer dis-
persions according to the invention, as one- or two-com-
ponent systems for sealing compositions.
The co-grafted polymer dispersions are prepared by
a procedure in which mixtures of an organopolysiloxane
containing terminal OH functional groups, an ethylene/
vinyl ester copolymer containing 5-99% by weight of inc-
orporated vinyl ester, preferably vinyl acetate, and one
or more vinyl monomers, if appropriate in the presence of
solvents or diluents, such as, for example, water, and,
if appropriate, molecular weight regulators, are brought,
in the presence of one or more agents which form free
radicals, to a reaction temperature which triggers off
the ~olymerization. If desired, it is also possible
for mixtures of organopolysiloxanes which contain terminal
Le A 20 508
` ~17~782
OH functional groups and non-functional organopolysilox-
anes to be introduced into the reaction mixture. The
~olymerization can be carried out by a.continuous or dis-
continuous process. In principle, the components to
be reacted can be added in any desired sequence, but the
best results are achieved when mixtures of the siloxane
and poly-(ethylene/vinyl ester) components and the vinyl
monomers are employed si~lultaneously in carrying out the
~?om~merization reaction.
The organopolysiloxanes containing terminal OH
groups are essentially linear and are represented by the
following formula:
,CH3 CH3 ,CH3
HO-Si-O ---- - Si Q ~ -- Si - OH
CH3 ~ CH3 _ CH3
- n = 10 to 5000
In addition to methyl groups, the organopolysiloxane
components can also contain up to 30 mol% of ethyl
groups, vinyl groups and phenyl groups, but methyl-sub-
stituted organopolysiloxanes are preferably employed.
The ethylene/vinyl ester copolymers employed are
prepared by the known processes of medium-pressure or
high-pressure synthesis, if appropriate in solvents,
such as tert.-butanol,or in aqueous emulsion.
Possible vinyl esters are organic vinyl esters of
saturated Cl-~18-monocarboxylic acids which are option-
ally substituted by halogen, in particular chlorine,
such as vinyl formate, vinyl acetate, vinyl propionate,
vinyl chloropropionate, vinyl butyrate, vinyl isobuty-
rate, vinyl laurate, vinyl myristate, vinyl stearate and
vinyl benzoate. Vinyl acetate is preferably employed.
Le A 20 508
~747~2
The molecular weights of the ethylene/vinyl ester copoly-
mers are bet~een abcut 1,000 ana over 1 million, preferably
between about 1,500 and 250,000.
If desired, the ethylene/vinyl ester copolymers
5 can be used in thecompletely or partially saponified ~orm.
Examples which may be mentioned of vinyl monomers
which are particularly suitable for the grafting reac-
tion are: olefins, such as ethylene, propylene and iso-
butylene, vinyl esters of aliphatic or aromatic carboxy-
lO lic acids, preferably vinyl acetate and vinyl propionate,~, ~unsaturated mono- or di-carboxylic acids and deriva-
tives thereof, compounds which may be mentioned being
(meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)-
acrylate, propyl or isopropyl (meth)acrylate, n-butyl,
15 iso-butyl or tert.-butyl (meth)acrylate, 2-ethylhexyl
(meth)acrylate, (meth)acrylamide, N-alkyl-substituted
(meth)acrylamide derivatives, (meth)acrylonitrile, mal-
eic anhydride, maleamide, N-alkyl-maleimides and maleic
acid half-esters or diesters, vinyl-aromatic compounds,
20 such as styrene, ~methylstyrene and 4-chlorostyrene,
vinyl chloride, vinylidene chloride, vinylidene fluoride,
tetrafluoroethylene and vinyl ethers, such as ethyl
vinyl ether and n-butyl vinyl ether; and from the series
of allyl compounds there may be mentioned allyl alcohol,
25 allyl acetate, isobutene diacetate, 2-methylenepropane-
l,3-diol, allyl ethyl carbonate and allyl phenyl carbon-
ate. If crosslinking or increase in the molecular
weights of the vinyl resin phase is desired, poly-unsat-
urated vinyl compounds or allyl compounds can be employ-
30 ed. Compounds which may be mentioned are divinylbenz-
ene, (meth)acrylates of polyhydric alcohols, such as,
for example, ethylene glycol dimethacrylate and diethy-
lene glycol diacrylate, and divinyl ether.
The free radical polymerization of the vinyl
35 monomers can be started in a manner which is in itself
Le A 20 508
~17~78Z
g
known, with the aid of agents which form free radicals,
UV-rays or ~- or ~-rays or by means of heat, without
further additives. Polymerization initiated by radia-
tion is preferably carried out in the presence of sensi-
tizer~ (compare, for example, A.D.Jenkins and A.Ledwith,Reactivity, Mechanism and Structure in Polymer Chemistry,
John Wiley and Son, London, New York, 1974, page 465).
To start the free radical polymerization of the
vinyl monomers, agents which form free radicals are em-
~310yed in amcunts of between about 0.001 and 2, preferably abcut0.02 and 0.8, % by weight, relative to the total mixture
of organopolysiloxane,EVA copolymer and vinyl monomer.
Examples which may be mentioned of agents which form
free radicals are azo initiators, such as bis-isobutyro-
nitrile (AIBN), azo-es~ers, azo-imino-esters or azo-N-
alkylamides, peroxides, such as di-tert.-butyl peroxide,
di-cumyl peroxide and di-benzoyl peroxide, peresters,
such as amyl perpivalate, tert.-butyl perpivalate, tert.-
butyl peroctoate, t-butyl perbenzoate and tert.-
butyl perneodecanoate, percarbonates, such as cyclohexylpercarbonate or bis-isopropyl percarbonate, or hydro-
peroxides, such as, for example, cumyl hydroperoxide and
tert.-butyl hydroperoxide.
Other suitable initiators are benzopinacol,
benzopinacol derivatives or other thermally highly sub-
stituted ethane derivatives.
The olymerization can also be started with the
aid of redox systems at lower temperatures than the
temperatures at which the agents which form free radi-
cals decompose purely thermally.
Examples of redox initiators which may be men-
tioned are combinations of peroxides and amines, such as
for example, benzoyl peroxide and triethylamine, tri-
alkyl-boron compounds and oxygen, hydroperoxides and
sulphinic acids, formaldehyde or aldoses or combinations
Le A 20 508
1~7~78Z
-- 10 --
with low-valent transition metal salts, or peroxide/S02
systems.
The polymerization reaction can be carried out
continuously or discontinuously, under normal pressure
or under reaction pressures of up to, for example, 300
bars, preferably up to 15 bars, and at reaction tempera-
tures between -20C and +250C, preferably at 70 to
190C ~f desired, the pOlymerizatio~ can also be
carried out in the presence of solvents or diluents, of
10 which there may be mentioned water, alcohols, such as
methanol, ethanol and tert.-butanol, aliphatic or aroma-
tic hydrocarbons, halogenated hydrocarbons, such as
chlorobenzene or fluorinated compounds, ethers, such as
dioxane or tetrahydrofuran, and esters, such as,for ex-
ample, ethyl acetate.
The polyinerization is preferably carried out,however, in the absence of a solvent.
If desired, the polymerization reaction can be
carried out in the presence of molecular weight regula-
tors. Examples of regulators which may be mentionedare mercaptans, such as n- or tert.-dodecylmercaptan,
thioglycol, thioglycerol and thioacetates. Also sul-
phur-free molecular weight regulators, such as hydrocar-
bons, examples which may be mentioned being paraffin
fractions, such as, for example, petroleum ether, light
petrol or wash benzine, and a-olefins, such as, for ex-
ample, propylene, isobutylene and l-butene, and further-
more ketones, such as, for example, acetone, methyl ethyl
ketone or cyclohexanone, and also aldehydes, such as, for
example, formaldehyde, acetaldehyde, propionaldehyde or
isobutyraldehyde, and allyl compounds, such as, for ex-
ample, allyl alcohol, allyl acetate, isobutene diacetate
or allyl carbonates. Other possible telogens are halo-
genated hydrocarbons, such as methylene chloride, tetra-
chloroethane, dibromoethane and the like. Aswas to be
Le A 20 508
117~78Z
-- 11
expected, the viscosities of the dispersions can be con-
trolled with the aid of such regulators.
The reaction of the monomers employed is deter-
mined by the polymeriza~ion process chosen and the re-
action conditions. In the case of a discontinuouspolymerization procedure, the objective is conversions
whlch are as high as possible, so that at least 80% of
the monomers employed, but preferably more than 90%, are
reacted. The residual monomers are removed by known
processes, by distillation under normal pressure or under
reduced pressure. The residual monomer contents still
effectively found in the dispersions after working up
are negligibly small; they are in general less than
1,000 ppm, and preferably less than lO0 ppm.
If desired, antioxidants,sta~ilizers UV-absorb-
ers, anti-aging agents, plasticizers and substances hav
ing a fungistatic or bacteriostatic action can be intro-
duced into the batch when the polymerization has ended.
The fillers customaril-y used in the preparation
of silicone elastomers can also be employed. Such
fillers are silicas which have been prepared by various
processes and have various specific surface areas.
The silicone-ethylene/vinyl ester copolymer-vinyl
polymer dispersions obtained according to the invention
are particularly suitable for use in 1- and 2-component
compositions which cure at room temperature. As is
known, such compositions, which cure in accordance with
the condensation principle, consist of polydiorgano-
siloxanes with hydroxyl end groups, crosslinking agents,
fillers and catalysts.
All or some of the polydiorganosiloxanes with
hydroxyl end groups can be replaced by the co-grafted
polymer dispersions according to the invention. Silanes
which have, in the molecule, at least 3 groups which can
easily be split off hydrolytically, such as carboxylic
Le A 20 508
~17~7~3Z
- 12 -
acids, carboxamides, oximes, amine oxides and amines,
are employed as the crosslinking agents. Examples of
reinforcing fillers are pyrogenically produced silicon
dioxide, and a non-reinforcing filler which can be used
is, for example, chalk. The catalysts used are, inter
alia, organic tin compounds, such as dibutyl-tin laurate.
Silicone compositions in which the co-grafted
polymer dispersions according to the invention are used
can be coated with commercially available lacquers, for
10 example, lacquers based on alkyd resins or polyurethanes,
considerably better than the silicone compositions known
hitherto. The silicone compositions which contain,
as constituents from which they are built up, the co-
grafted polymers according to the invention and which
15 have been cured at room temperature can be lacquered in
the same manner as wood. It has also been found that
the adhesion of these novel systems to wood, metals and
concrete is excellent, even under wet conditions. The
following examples illustrate the preparation of the
silicone-ethylene/vinyl ester copolymer-vinyl polymer
dispersions according to the invention.
Preparation of the starting substances:
The polysiloxanes with OH functional groups are
prepared in a manner which is in itself known (compare,
for example, W. Noll, Chemie und Technologie der Silikone
(Chemistry and Technology of Silicones), Verlag Chemie
GmbH, Weinheim/Bergstr., 2nd edition, 1968, chapter 5,
page 162 et seq.).
The polydimethylsiloxanes with OH functional
groups given in the examples are characterized as follows:
OH-~olvsiloxane No. ViscositY (mPas) at 20C
~ v _ ~
1 5,000
2 10,000
3 - 18,000
4 50,000
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- 13 -
The ethylene/vinyl ester copolymers (EVA) are
characterizedby the following data:
EVA Vinyl acetate content ~ ~ [dl/g]
(% by weight)
A 45 1.4
B , 42 0.15
C 44 0.09
D 62 1.4
E 45 0.25
Example 1
1,000 g of OH-polysiloxane 1 are warmed to 110C
under nitrogen in a 3 1 kettle.
A solution of 350 g of styrene, 350 g of n-butyl
acrylate, 300 g of EVA E and 3.5 g of benzoyl peroxide
is then added dropwise in the course of 3 hours. The
15 mixture is then subsequently stirred for a further 3
hours at 110C. The unreacted monomers are removed by
distillation. A homogeneous, white dispersion with a
viscosity of 43,000 (mPas) at 25C is obtained.
Example 2
1,000 g of OH-polysiloxane 1 are heated to 110C
under nitrogen in a 3 1 kettle and a solution of 700 g
of styrene, 300 g of EVA E and 3.5 g of benzoyl peroxide
is then added in the course of 3 hours. The mixture
is subsequently stirred at 110C for 3 hours and the
25 volatile constituents are stripped off in vacuo. A
stable dispersion with a viscosity of 48,000 (mPas) is
obtained.
Example 3
14.5 kg of OH-polysiloxane 1 and 4.35 kg of EVA B
30 are warmed to 110C under nitrogen in a 40 1 stirred
autoclave. 2 solutions are then simultaneously added
dropwise in the course of 3 hours:
Solution 1: 9 kg of vinyl acetate
Solution 2: 1.15 kg of vinyl acetate and 51 g of ben-
35 zoyl peroxide.
Le A 20 508
~L747~
- 14 -
The mixture is then subsequently stirred for a
further 3 hours at 110C. The volatile constituents
are removed by distillation in vacuo. ~ A homogeneous,
fine-particled dispersion with a viscosity of 33,000
(mPas) is obtained.
Examples 4 and 5
The solutions given in the table are added to
14,500 g of OH-polysiloxane 1 at 110C under nitrogen in
a 40 1 stirred autoclave:
10 Ex- Styrena n-Butyl EVA Benzoyl Viscosity
ample acrylate B C peroxide (mPas)
No. q
4 5075 5075 4350 - 51 24,000
5075 5075 - 4350 51 28,000
The mixture is then subsequently ~,~ol-~merized for
a further 3 hours at 110C to a monomer conversion of
92%. The volatile constituents are removed by dis-
tillation in vacuo. The finished dispersions have the
viscosities given in the table.
Example 6
1,000 g of OH-polysiloxane 2, 200 g of EVA A, 500
g of styrene and 50 g of methyl acrylate are warmed to
200C in a 3 1 pressure autoclave,while stirring with
a blade stirrer. A solution of 1.8 g of di-tert.-
butyl peroxide in 300 g of styrene, 50 g of methyl acry-
late and 0.5 g of tert.-dodecylmercaptan is added at
200C in the course of 2 hours. After stirring the
mixture for a further 2 hours, it is cooled and the pro-
duct is drained off. The monomer conversion is vir-
tually quantitative. The viscosity of the dispersionis 14,500 (mPas).
Example 7
100 g of OH-polysiloxane 1 are warmed to 170C.
A solution of 18.75 g of EVA A in 71.25 g of styrene,
10 g of methacrylate and 0.55 g of tert.-butyl perpiva-
late is then added in the course of 1 hour. The solu-
Le A 20 508
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~L~7478~
- 15 -
tion is then subsequently stirred at 170C for 1 hour
and the volatile constituents are then removed by dis-
tillation. The finished dispersion has a viscosity of
24,000 (mPas).
Example 8
1000 g of OH-polysiloxane 1 are warmed to 80C
under nitrogen, and a solution of 2,360 g of tert.-
butanol, 640 g of EVA D, 1000 g of vinyl acetate and 6 g
of tert.-butyl perpivalate is added in the course of 2
hours, while stirring. The mixture is then subse-
quently stirred at 80C for 4 hours. The solvent and
residual monomers are removedby distillation. The re-
sulting dispersion has a viscosity of 147,000 (mPas).
Example 9
500 g of E~A A are dissolved in 2000 g of tert.-
butanol at an internal temperature of 80C under nitrogen
in a 6 1 stirred kettle. A solution of 500 g of vinyl
acetate, 500 g of tert.-butanol and 1.5 g of tert.-butyl
perpivalate is then added and the mixture is stirred for
2 hours. A solution of 1,000 g of OH polysiloxane 3,
500 g of vinyl acetate and 2 g of tert.-butyl perpiva-
late is then added dropwise in the course of 1 hour.
The mix~ure is subsequently stirred for 4 hours and the
solvent and residual monomers are then distilled off. -
The homogeneous dispersion has a viscosity of 141,000(mPas). The compositions prepared by the process des-
cribed here were mixed according to the following recipe
and cured under the influence of moisture, with the aid
of crosslinking agents and catalysts which promote cross-
linking: 200 g of co-grafted polymer, 10.4 g of a
titanium complex of the following approximate com-
position:
Le A 20 508
.
1~7478Z
- 16 -
3 ~2 (
C2H5 2
11.4 g of bis-(N-methylbenzamido)-ethoxymethylsilane and
2.2 g of dibutyl-tin diacetate.
The crosslinked products are elastic and free
from tackiness. They were coated with an alkyd
lacquer, the adhesion of which to the silicone was deter-
mined after 7 days with the aid of the cross-hatch test,
by cutting a 2.54 cm square on the lacquered surface in-
to 100 square pieces of equal size with a razor blade,
so that a painted surface with a grid-like appearance is
obtained. A strip of adhesive tape (tesa film No.
101 from Messrs. Beiersdorf AG, Hamburg) is then pressed
firmly onto this grid. Thereafter, the strip of ad-
hesive tape is removed by being slowly pulled off at an
angle of about 30C. The percentage value of the re-
tention of the lacquer is obtained from the number of
painted square pieces which remain on the cured formu-
lation after the strip of adhesive tape has been re-
moved. The physical properties and the results of the
cross-hatch test can be seen from the following table.
For Comparison Examples 10 and 11, instead of the
co-grafted polymersj polysiloxane 1 is used in Example
10 and polysiloxane 4 is used in Example 11.
Le A 20 508
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-- 17 --
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