Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1339227
Graft polymers made from (meLh)acrylic acid derivatives
and silicone resins
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to graft polymers made from
(meth)acrylic acid derivatives and alkoxy-functional
silicone resins, a process for their preparation, and
their use as impregnating agents, in particular, in
building protection.
8ACKGROUND INFORMATION
The use of silicone resins of various composition
as impregnating agents, waterproofing~agents and buil-
ding-protection agents has long been known. Alkoxy-
functional, oligomeric siloxanes which crosslink under
the action of moisture, if appropriate in the presence
of a catalyst, have proven particularly advantageous for
~hese uses.
Furthermore, the use of mixtures comprising co-
polymers of methyl methacrylate and siloxane resins for
pigmented paints or impregnating agents has been dis-
closed by DE-OS (German Published Application)
2,150,736, DE-OS (German Published Application)
2,352,242 and DE-AS (German Published Specification)
1,671,280. The advantage of such mix~ures is the simple
preparation, but the disadvantage is serious and com-
prises a tightly limited compatibility between siloxaneresin and polymethyl methacrylate,
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This incompatibili~y of the polymers necessarily
leads to separation of ~he mix~ure componen~s during
film forma~ion and on pene~ra~ion in~o ~he building
material.In order ~o limi~ ~he incompatibili~y and ~en-
dency ~owards separa~ion of ~he componen~s, firs~lyhigh-aroma~ic solven~s and secondly applica~ion from
grea~ly dilu~ed solution are necessary.
Combina~ions of siloxane resins and acrylate resins
are very desirable. After all, besides wa~er repulsion,
silicone resins also have excellent water vapor perme-
ability, whereas acrylate resins offer be~er pigment
binding capacity and better protection agains~, for
example, calcification. On the oLher hand, the wa~er
vapor permeability of acryla~e and methacryla~e co-
polymer films is low.
Pain~s and impregna~ing agents which combine the
advan~ages of bo~h sys~ems and comprise compa~ible, non-
separa~ing, highly hydrolysis-resistant combinations are
therefore very advan~ageous and desirable.
SUMMARY OF THE INVENTION
The invention has ~he objec~ of providing compat-
ible silicone/acryla~e resin combina~ions for impreg-
nating agen~s and ex~erior wall paints which crosslinkby means of a~mospheric mois~ure.
It was possible ~o achieve the objec~ by providing
alkoxysilicone resinl(meLh)acryla~e graf~ polymers which
are linked in a hydrolysis-stable manner.
The invention ~herefore rela~es ~o alkoxysilicone
resin/(meth)acrylate graft polymers, a process for their
preparation, and ~heir use as pain~s and impregnating
agen~s.
The inven~ion rela~es ~o graf~ polymers which are
characterized in ~hat free radical polymerization is
carried ou~ in ~he presence of
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1. 10 - 90% by weight, preferably 30 - 65% by weight,
of an oligomeric, alkoxy-functional silicone resin, and
2. 90 - 10% by weight, preferably 35 - 70% by weight,
of a mixture of components consisting essentially of (i) (meth)_
acrylic acids selected from the group consisting of acrylic acid
and methacrylic acid, (ii) alkyl ester derivatives of said acrylic
acid or said methacrylic acid,(iii) OH functional derivatives of
said acrylic acid or methacrylic acid, where the sum of the
components is always 100% by weight, and the alkoxy-functional
silicone resin corresponds to the general formula
RXsi(oR )y~4~x~y
and x has a value of 0.75 to 1.7, and
y has a value of 0.2 to 2, and where
R denotes a linear or branched alkyl radical having
1-20 C atoms, an alkylaryl radical and/or an optionally
substituted aryl radical,
R' denotes a linear or branched alkyl radical having
1 to 18 C atoms.
Preferably component2. above is composed of:
a) 0.2 - 99.8% by weight, preferably 15 - 95% by
weight, of methacrylates,
b) 99.8 - 0.2% by weight, preferably 95 - 15% by
weight, of acrylates, and
c) 0 - 80% by weight, preferably 0 - 20% by weight,
of (meth)acrylic acid (meth)acrylamide, (meth)acrylonitrile,
vinyl aromatics, ~-olefins, vinyl esters, allyl compounds, iso-
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propenyl compounds, or polyfunctional derivatives thereof, or
mixtures thereof,
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and furthermore to a process for the preparation thereof
by free-radical graft polymerization in solution or in
the solid phase, and to the use as impregnating agents
or paints, in particular in building protection, of the
graft polymers thus obtained.
DETAILED DESCRIPTION OF THE INVENTION
The silicone resins used according to the invention
as the graft base are known products whose preparation
is described in W. Noll, Chemie und Technologie der
Silicone ~Chemistry and technology of the silicones],
2nd edition, Verlag Chemie, Weinheim, 1968, pp. 551 ff.
~5 The alkoxy groups present can optionally be methoxy,
ethoxy, isopropoxy or butoxy groups. For economic rea-
sons and due to its high reactivity, the methoxy group
is particularly preferred here. Similarly, the silicone
resins contain, besides methyl and phenyl, alkyl substi-
tuents having linear or branched chains of the general
formula CnH2n+1 where n = 2-20 on silicon. Particularly
preferred silicone resins are those which have branched
alkyl substituents on the Si atom. Furthermore, the si-
licone resins can contain tri- or tetrafunctional bran-
ching points. The viscosities of solutions of these re-
sins in alcohols or hydrocarbons are low in order toensure good penetration, for example, in building ma-
terials. In a solid after hydrolysis of the alkoxy
groups of 60 - 65% by weight, the viscosity of the so-
lutions used is preferably below 2000 mPa.s, and more
preferably below 200 mPa.s.
Suitable solvents are preferably aromatic hydro-
carbons; aliphatic hydrocarbons; alcohols; such as
ethanol or isopropanol; esters, such as butyl acetate;
or mixtures thereof.
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Acrylic acid , methacrvlic acid and their deriva-
tives, preferably their alkyl esters, are monomers that
can be employed according to the invention for the graft
reaction. The methyl, ethyl, isopropyl, propyl, n-butyl,
isobutyl and higher alkyl esters having up to 25 C atoms
in the alkyl component are examples of alkyl esters for
use in the present invention. OH functional ester deri-
vatives of acrylic and methacrylic acid can likewise beemployed. Particular effects can be achieved by copoly-
meriza~ion of, if appropriate, mixtures of vinyl aroma-
tics, such as styrene or ~-methylstyrene, (meth~acrylo-
nitrile, (meth)acrylic acid or vinyl acetate, ~-olefins,
allyl and isopropanyl compounds, or the polyfunctional
derivatives thereof with alkyl (meth)acrylates.
The polymerization can be initiated by known free-
radical ;nitiators based on azo compounds or peroxide
compounds, such as, for example, dibenzoyl peroxide,
4,4'-dichlorobenzoyl peroxide, di-tert.-butyl peroxide,
dicumyl peroxide, tert.-butyl pivalate, tert.-butyl
peroctoate and cyclohexyl percarbonate, or redox systems
comprising peroxide or hydroperoxide components on the
one hand and reducing agents on the other hand, at
temperatures between -80~C and +250~C, preferred poly-
merization temperatures being l50~C to l180~C. The poly-
merization can furthermore be initiated photochemically
or by radiation activation. The polymerization is
carried out in solution or without addition of solvent.
Suitable solvents are the abovementioned aliphatic or
aromatic hydrocarbons,
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alcohols, ketones or esters. Preferred solvents or sol-
vent mixtures are those ~hose flashpoint according to
DIN ;s above 21~C.
The molecular ~eight of the graft polymer com-
ponent is controlled by the reaction temperature, solvent,
type and amount of initiator, and, if appropriate, by
molecular-~eight regulators. The graft reaction itself
and the graft yield can be controlled by graft activators.
Suitable graft activators are graft- and transfer-active
monomers. Graft activators ~hich can be employed are
allyl compounds; such as allyl alcohol, allyl acetate
and other allyl esters of aliphatic or aromatic carboxylic
acids; allyl carbonate derivatives, diallyl and polyallyl
compounds, such as diallyl phthalate, triallyl cyanurate,
triallyl citrate, allyl ethers and diallyl ethers. Impor-
tant graft activators are furthermore vinyl acetate, acry-
lonitrile, vinyl chloride, ethylene, propene, isobutylene
or 1-butene and diisobutylene as examples from the series
comprising active ~-olefins. The graft reaction accord-
ing to the invention is preferably carried out using 0.01to 20X by weight of graft activators, relative to the
total sum of the reaction components employed, and the
products thus obtained.
By means of the graft reaction, it is possible to
combine acrylate and alkoxysiloxane resin components which
are incompatible per se to a clear film-compatible coat-
ing resin.
The mixtures described above of specific silicone
resins (DE-OS (German Published Specification) 2,352,242)
and methyl polymethacrylate (DE-AS (German Published
Specification) 1,671,280) can be employed as exterior pro-
tecting paints only from specific solvent combinations
having a lo~ solids content or only in certain combina-
tions. Physically, they are mixtures of incompatible poly-
mers. A drastic improvement in compatibility of the
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silicone resin and acrylate resin component can be achie-
ved through the graft reaction. Furthermore, separation
of the silicone and the acrylate resin component is avoi-
ded through the binding of the graft resin component to
the silicone resin via a hydrolysis-stable Si-C bond, so
that the building material is also adequately protected
in the entire penetration region. furthermore, it is pos-
sible to obtain a pigmented paint having high color sta-
bility and gloss retention by adding to the graft poly-
mer solution inorganic or organic colored pigments ~hichoccurs under the conditions ~hich are conventional in
industry.
The impregnating agents and paints according to
the invention can be crosslinked by atmospheric moisture.
Catalysts can be employed to accelerate the crosslinking
reaction. These catalysts are kno~n and described, for
example, in W. Noll, Chemie und Technologie der Silicone
~Chemistry and technology of the silicones], 2nd edition,
1968, pp. 181 ff. In general, the crosslinking catalysts
used are soluble organometallic compounds, such as Sn, Mn
or Fe derivatives. The amount of catalyst, relative to
the solids, depends on various factors, such as substitu-
ents, film hardness desired and hardening time, and is
usually 0.01-5% by weight, preferably 0.5-2% by ~eight.
The graft polymers according to the invention are
used as impregnating agents for building materials and
concrete, furthermore as exterior ~all paints.
The subject-matter of the present invention will
be illustrated in greater detail with reference to the
follo~ing examples.
For the experiments described below, the silicone
resins corresponding to the follo~ing formulae are used:
Silicone resin A: (Me)o.7(i-Bu)o~3si(o)1~os(oMe)o 9
Me = methyl radical
i-8u = isobutyl radical
Silicone resin B: MeSi(0)1 1(0Me)o 8
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Silicone resin C: (Me)1.0R0.2R 0.1Si(o)1.o(oMe)o-7
R = C12-alkyl radical
R' = C14-alkyl radical
The solids specified in the examples Yere deter-
mined after cleaving off the alkoxy groups, by hydrolysisof the alkoxy groups, by hydrolysis using alcoholic hydro-
chloric acid, evaporating off the acid and the volatile
components in a drying cabinet at 105~C for 3 hours.
Unless other~ise stated, the viscosities of the
graft polymer solutions Yere determined using a Haake Vis-
kotester at 23~C.
Example 1:
11 kg of silicone resin A (100% strength) and
2.5 kg of test benzine (benzine fraction having
the boiling point range 155~C-185~C)
are heated to 100~C under a stream of nitrogen.
2 solutions are then pumped in simultaneously and
uniformly Yithin 2 hours:
Solution 1: 5.1 kg of isobutyl methacrylate
1.0 kg of n-butyl acrylate and
1.0 kg of hydroxypropyl methacrylate
Solution 2: 4.4 kg of test benzine (benzine fraction
155~C-185~C)
0.2 kg of tert.-butyl peroctoate and
0.25 kg of ditert.-butyl peroxide
The reaction is then carried out to completion
for
1 hour at 120~C
and 2 hours at 130~C.
After cool;ng, catalysis is effected Yith 150 9
of dibutyltin dilaurate. The product then has a viscosity
of 172 mPa.s and a solids content of 60.5%. A film pro-
duced using this solution is highly transparent, has im-
peccable Yater- and C02-repellent properties and has high
Yater vapor permeability.
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Example 2:
In a 5 liter. reactor,
1.6 kg of silicone resin A and
0.4 kg of test benzine (benzine fraction 155 -
S 185~C)
are heated to 112~C under nitrogen.
Solution 1 and 2 are pumped in within 2 hours:
Solution 1: 800 9 of isobutyl methacrylate
200 9 of methyl methacrylate
175 9 od n-butyl acrylate and
150 9 of 3-hydroxyethyl methacrylate
Solution 2: 1 kg of test benzine and
35 9 of tert.-butyl peroctoate.
~hen the addition is complete, the mixture is
stirred for 2 hours at 112~C and 1 hour at 120~C.
After cooling, the product has a solids content
of 61.0X by weight and a viscosity of 1700 mPa.s. After
addition of 0.5% by weight of dibutyltin dilaurate, rela-
tive to the solids content, the film has completely har-
dened and is highly transparent after 24 hours.
Example 3:
Test as a water-repellent impregnating agent for
mineral building materials
A graft polymer prepared in accordance with the
process described above and having the composition shown
in Example 1 is diluted to about 9% by weight with test
benzine. Test samples of various building materials are
prepared by dipping once into the impregnating solution.
The immersion time is 30 seconds. The samples thus pre-
pared are stored for 6 days at 23~C and a relative
humidity of about 50% and subsequently dried at 50~C for
24 hours.
The capillary absorption of water at an immer-
sion depth of 3 mm is then determined.
Compared to untreated test samples (values in brac-
kets), the following results are obtained.
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~ater absorption in Z by weight
2 hours 6 hours 24 hours
Lime-cement
plaster 0.6 (11.4) 0.7 (11.6) 1.0 (11.6)
Cement mortar 0.3 ( 6.1) 0.5 ( 6.4) 0.8 ( 6.4)
Lime sand brick 0.3 (11.9) O.S (12.0) 0.9 (12.2)
From the values, it can be seen that the untrea-
ted building materials are saturated with ~ater after only
2 hours, whereas the test samples treated ~ith the graft
polymer according to the invention exhibited only a slight
increase in weight even after storing for 24 hours in
~ater.
Example 3a Comparison experiment
The experiment from Example 3 is repeated using
a 9% strength solution of a resin prepared by polymeriza-
tion of isobutyl methacrylate.
~ater absorption in % by ~eight
2 hours 6 hours 24 hours
Lime-cement
plaster 0.8 (11.4) 1.5 (11.6) 2.9 (11.6)
Cement mortar 0.4 ( 6.1) 1.0 ( 6.4) 2.4 ( 6.4)
Lime sand brick 0.4 (11.9) 0.8 (12.0) 1.8 (12.2)
From the values, it can be seen that the good
waterproofing sho~n in Example 3 is not achieved.
Example 4:
Test for water vapor and carbon dioxide perme-
a~ y
The diffusion resistance figures ~ are tested in
accordance with DIN 53 122 giving the follo~ing values
~hen the solution of the graft polymer from Example 3 is
used
H20 2,460
~2 2,350,000
Example 4a Comparison experiment
The test in Example 4 are repeated using a commer-
cially available impregnating agent based on polysiloxane
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(A) and the isobutyl methacrylate polymer (a) used in
Example 3a.
H20 (A) 0 (~) 26,500
~ C~2 (A) 0 (P) 2,000,000
The values found show that the graft polymer
according to the invention puts up a high resistance
against penetration of carbon dioxide into the building
material, while the water vapor permeability is scarcely
affected. This property profile is desired (prevention
of carbonation damage).
The comparison experiments show that commercially
available impregnating agents based on polysiloxane have
no carbonation protection, whereas pure polyacrylate res-
ins, while exhibiting adequate carbonation protection,
do not exhibit the high water vapor permeability required
for building protection.
Literature: R. Engelfried, Defazet issue 9 - 1977
pages 353-359.
Example 5~
Preparation of a pigmented building protection
paint
The good physical properties regarding building
shown in Examples 3 and 4 permit the preparation of a
pigmented exterior wall coating, which is prepared, for
example, according to the following recipe:
Graft polymer
60% strength solution in test benzine 300.00 parts by weight
Titanium dioxide rutile type75.59 parts by weight
Iron oxide pigment (yellow)5.94 parts by weight
30 Iron oxide pigment (black5.94 parts by weight
Chromium oxide green1.84 parts by weight
Talcum 56.69 parts by weight
Solvent for correcting
the viscosity40 to 100.00 parts by weight
Application takes place by brushing. 2 coats
are applied 24 hours apart. The dry film thickness is
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80 to 120 ~m. The test in an accelerated weathering
apparatus according to DIN 53 2~1 produces no visible
changes after a test time of 2000 hours.
It will be appreciated that the instant specifica-
tion and claims are set forth by way of illustration and
not limitation, and that various modifications and
changes may be made without departing from the spirit
and scope of the present invention.
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