Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
PATENT
CASE D 7421
THERMOPLASTIC ELASTOMER CONTAINING
JOINT SEALING COMPOUND
BACKGROUND OF THE INVENTION
1. Fleld of _ e Inventlon
Thls Inventlon relates to a Jolnt sealIny compound
based on thermoplastlc elastomers prepared from elastlc
polybutadlene or polylsoprene onto whlch styrene has
been gra~ted, thus addltlonally provldlng the polymers
wlth thermoplas~lc propertles.
2. Statement of Related Art
Thermoplastic polymers oF the block copoiymer type
are known from the llterature. They conslst of a
central block of butadlene or Isoprene whlch has
elastomerlc propertles. Thermoplastlc vlnyl polymers,
partlcularly styrene, are then polymerlzed as a ter-
mlnal bloc~ onto ~hls central block. The elastlclty
behavlor of polymers such as these Is determlned, In
certaln temperature ranges, by the elastomer unlts,
whlle other propertles, partlcularly the thermoplastlc
propertles, are determlned by the styrene grafted on.
Accordlngly, It has be~en proposed to use polymers
such as these, Inter alla, for Jolnt sealIng compounds.
Hydrocarbon r,eslns, alkylated hydrocarbon reslns, ter-
pene phenollc reslns and so on may then be added to the
Jolnt seallng compounds to modlfy thelr propertles.
However, modlfylng addltlves such as these frequently
brIng about a reductlon In stablllty In the sealed
Jolnt, and In addltlon are not caPable of wlthstandlng
permanent stresslng.
STATEMENT OF THE INVENTION
Other than In the operatlng examPles, or where
otherwlse Indlcated, all numbers expresslng quantltles
of Ingredients or reactlon condlt I ons used hereln are
to be unders~ood as modlfled In all Ins~ances by the
term "about."
An obJect of the present Inventlon Is to comblne
the known thermoplastlc elastomers wlth raw materlals
of the type whlch brlng about an Improvement In adhe-
slon In the Jolnt sealIng composltlon, but whlch do not
have any of the dlsadvantages of the reslns hltherto
used for thls purPose.
The present Inventlon relates to Jolnt seallng
composltlons based on block copolymers of an elastlc
central block of polybutadlene or polylsoprene wlth
polystyrene grafted thereon and a content of elastomers
and solvents, and optlonally also standard auxlllarles,
such as synthetlc thermoplasts, flllers, thlxotroplcl-
zlng agents, prlmer~, antlagers and the llke. The new
Jolnt seallng composltlons contaln, based on the com-
posltlon as a whole, from 0.3 to 30% by welght of a
copolymer of methacrylates of allphatlc monoalcohols
(alkanols) contalnlng from 1 to 4 carbon atoms, a
calculated average of from 1.5 to 3.0 carbon atoms
belng present In the alcohol component and the molar
proportlon of methanoi In the alcohol comPonent
amountlng to at least 25%. Whlle a copolymer of two
--2--
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methacrylate is preferred, copolymers of three or more such methacrylates can
also be employed, provided the above criteria are met.
The basic constituent of the new joint sealing composition is a
thermoplastic block copolymer of an elastic central block of polybutadiene or
polyisoprene with polystyrene grafted thereon, which are commercially
available from various companies. They differ somewhat from one another,
particularly in solution, with respect to their viscosity and their flow
properties, particularly in the case of highly concentrated solutions.
Suitable solvents for this prupose are organic solvents, e.g. hydrocarbons,
such as cyclohexane, toluene, xylene, or petroleum ether. Other organic
solvents are ketones, such as methylbutyl ketone, or chlorinated hydrocarbons.
The compositions of the invention contain from 20 to 50% by weight,
based on the composition as a whole, of solvent, and from 20 to 50% by weight,
based on the composition as a whole, of thermoplastic block copolymer having
an elastic central block of polybutadiene or polyisoprene with polystyrene
grafted thereon.
In addition, the joint sealing compositions of the invention also
contain other rubber-like polymers. Suitable rubber-like polymers of this
type are relatively low molecular weight commercial types of polyisobutylene,
polyisoprene or polybutadiene-styrene. Degraded natural rubber or neoprene
rubber may also be used. Rubbers which are still liquid at room temperature,
of the type frequently referred to as "liquid rubber", may also be used here.
The rubber-like polymers are present in a quantity of from 30 to 50% by
weight, based on the composition as a whole. The quantity in which they are
present should be considered in conjunction with the quantity of thermoplastic
elastomer present.
Thus the present invention provides, in one aspect a joint sealing
composition comprising:
A. from about 20 to about 50% by weight of at least one
; thermoplastic block copolymer having an elastic central block of
polybutadiene or polyisoprene with polystyrene grafted thereon;
B. from about 20 to about 50% by weight of at least one organic
solvent:
724
C. from about 0.3 to about 30% by weight of at least one copolymer
of methacrylate of aliphatic monoalcohols containing from 1 to 4
carbon atoms, having a calculated average of from 1.5 to 3.0
carbon atoms in the alcohol moleties, and wherein the molar
percentage of methanol in the alcohol moleties is at least 25%;
D. from about 30 to about 50% by weight of at least one rubber-like
polymer;
; E. from O to about 5~ by weight of at least one thixotropicizing
agent; and
F. from O to about 2~ by weight of at least one mercaptoalkylsilane.
In another aspect, the invention provides in a joint sealing
composition containing a thermoplastic b:Lock copolymer, an organic solvent,
and a rubber-like polymer, the improvement comprising the presence of from
about 0.3 to about 30~ by weight of at least one copolymer of methacrylates of
allphatlc monoalcohols eontalning from 1 to 4 carbon atoms, having a
calculated average of from 1.5 to 3.0 carbon atoms in the alcohol moleties,
and wherein the molar percentage of methanol in the alcohol moleties is at
least 25%.
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As dlscussed above, the composltlons of the Inven-
tlon contaln as an essentlal constltuent from 0.3 to
30% by welght of a copolymer of methacrylates of C1-C4
allphatlc monoalcohols. The methacrylate copolymers
are present In a quantlty of preferably from 3 to 25
by welght, and more preferably of from 5 to 12% by
welght, based on the composltlon as a whole. These
methacrylate copolymers are commerclal products whlch
can be characterlzed by thelr reduced vlscoslty of from
20 to 60 cm3/g and preferably of from 25 to 40 cm3/g.
The reduced vlscoslty Is measured In chloroform at 20 C
uslng known methods. Even very small quantltles of
these methacrylate copolymers produce dlstlnctly
dlscernlble enhanced adheslon of the composltlons of
the Inventlon, even to smooth surfaces.
As already dlscussed, other auxlllarles may or
should be used In the preparatlon of the Jolnt sealIng
compounds, partlcularly thlxotroplclzlng agents In a
quantIty of from 0 to 5%, preferably 0.5 to 5% by
welght, and more pr0ferably In a quantlty of from 1 to
4% by welght, based on the composltlon as a whole.
Sultable thlxotroplclzlng agents are the known
thlxotroplclzlng agents, such as bentonltes, kaollns,
or organlc compounds, such as hydrogenated castor oll
2~ or derlvatlves thereof wlth polyfunctlonal amlnes. or
the reactlon products of stearlc acld or rlcinolelc
acld wlth ethylenedlamlne. It has proven to be par-
tlcularly advantageous to use slllca, more especlally
slllca obtalned by pyrolysls.
In addltlon to the thlxotroplclzlng agents, prl-
mers can also be used, such as 0 to 2%, preferably 0.01
to 2% by welght, based on the composltlon as a whole,
of a mercaptoalkylsllane. It has proven to be par-
tlcularly advantageous to use a monomercaptoalkyl
trlalkoxysllane. Mercaptopropyl trlmethoxysllane for
-4-
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example Is com~erclally avallable.
The sealIng composltlons of the Invention can be
used for bondlng to one another or for sealIng a
varlety of materlals. Although prImarlly Intended for
use on concrete, glass, plaster and/or enamel, and also
on ceramlcs and porcelaln, the sealIng composltlons of
the InvPntlon can also be used for bondlng or sealIng
moldlngs or proflles of alumlnum, steel, or zlnc, or
of plastlcs, such as PVC or Polyurethanes or acryllc
reslns. Flnally, the seallng composltlons of the
Inventlon can also be used for bondlng wood or wood
materlals to a varlety of other materlals.
The composltlons of the Inventlon have been used
wlth partlcular success for sealIng slllcate-contalning
materlals, such as for exampl0 glass, ceramlcs, porce-
laln and/or enamel. In the ca~e of glass, the absence
of the methacrylate copolymer addltlve of the Invention
results In a very conslderable reductlon In elastlclty
modulus and In adheslon to the glass surface. Adheslon
Is almost completely lo~t In the absence of the
methacrylate copolymers. By sultably coordlnatlng the
quantlty of copolymers wlth a glven baslc mlxture of
the other Ingredlents of the formulatlon, adheslon can
be adJusted to any deslred level. Slnce the coheslon
2~ of the composltlon Is good, varlatlon of the quantlty
of copolymer can lead to seallng composltlons whlch may
readlly be removed agaln at a later stage.
The Inventlon wlll be Illustrated but not llmlted
by the Followlng examples.
EXAMPLES
EXAMPLE 1
In a planetary dlssolver, a base mlxture was pre-
pared from 300 parts by welght toluene, 280 parts by
welght of a block copolymer of polybutadlene wlth
7;~4
grafted-on polystyrene (commerclal product Carlflex TR
1000) and 370 parts by welght of Polylsobutylene
(commerclal product Oppanol B1). 100 parts by welght
of a thermoplastlc copolymer based on 15 mol %
methyImethacrylate wlth 85 mol % butyImethacrylate
(reduced vlscoslty 30 cm3/g, as measured In chloroform
at 20 C) were then added to the mlxture thus prepared.
: Durlng mlxing, the mlxtllre underwent an Increase In
temperature to 35 - 40C.
EXAMPLE_ 2
10 g of mercaptopropyl trlmethoxysllane were added
to the base mlxture of Example 1.
EXAMPLE 3
10 9 of mercaptopropyl trlmethoxysllane and 20 9
of pyrogenlc slllca (speclflc surface 150 m2/g) were
added to the base mlxture of Example 1.
EXAMPLE 4
20 9 of the same pyrogenlc slllca as In Example 3
were added to the base mlxture of Example 1.
Test specImens were prepared from the mlxtures of
the above examples for the purpose of determlnlng the
adheslon values and mechanlcal behavlor on contact ele-
ments of glass. The dlmenslons of the test speclmens
were selected In accordance wlth the standard normally
used for testlng Jolnt sealIng compounds (DIN 18 545,
sheet 2) In such ~ way that a volume of 12 x 12 x ~0 mm
was ~IIIed between the glass elements. The tes~ specl-
mens thus prepared were then stored under dlfferent
condltlons:
72,~
a) drylng for 5 weeks In a standard cllmate (23C
2C and 50% + 5% rel. humldlty)
b) drylng for 4 weeks In a standard cll~ate followed
by storage for 1 week at ~70C
5c) drylng for 4 weeks In a standard cll~ate followed
by storage In water ~or 1 week.
Some of the test specImens stored In the standard
cllmate were elongated to fallure whlle all the others
10were elongated by 50%, the elongatlon belng malntalned
over a perlod of 24 hours through the Insertlon of spa-
cers. Thereafter the Jolnt sealIng compounds were exa-
mlned for bondlng behavlor (adheslon) and for posslble
materlal fractures (coheslon).
15The test speclmen obtalned In accordance wlth
Example 1 had an E-modulus of 0.12 N/mm2 after storage
under condltlons a) and b) and a correspondlng value of
0.11 N/mm2 after storage under condltlons c), adheslon
fallure belng observed. Wlth Example 2, an E-modulus
20o~ 0.11 N/mm2 was measured after storage under con-
dltlons a) and c). adheslon fallure belng observed.
After storage under condltlons b), the E-modulus
measured 0.12 N/mm2 and no adheslon fallure was
observed. After storage under condltlons a), elonga-
2~tlon at break measured 349% and the E-modulus 0.34
N/mm~.
After storage under condltlons a) and b), the test
speclmens of Example 3 showed E-modull of 0.11 N/mm2 In
elther case and no adheslon fallure was observed. Even
30after storage under condltlons b), an E-modulus of 0.10
N/mm2 was measured wlthout any adheslon fallure.
The breaklng elongatlon of test speclmens a~ter
storage under condltlons a) produced a value o~ 382%,
the E-modulus In thls case Increaslng to 0.38 N/mm2.
35The test specImens accordlng to Example 4 produced
7~1
an E-modulus after storage under condltlons a) and b)
of 0.1 N/mm2 wlthout any adheslon fallure occurrlng.
The breaklng elongatlon after storage under condltlons
a) was measured at 323% for an E-modulus of 0.34 N~mm2.
COMPAR ! SON EXAMPLES
Examples 2, 3, and 4 were repeated, but wlthout
the addltlon of the me!thacrylate copolymer. After
storage under condltlons a), b) and c), Comparlson
Examples 2 and 3 produced an E-modulus of from 0.05 ~o
0.04 whlle Comparlson Example 4 could not be measured
for Its E-modulus at 50% because adheslon fallure
occurred beforehand. The same applled In the case of
ComparIson Example 1, whlch was prepared as In Example
1 but wlthout the addltlon of the methacrylate copo-
Iymer. In thls case, too, It was not posslble to
measure the E-modulus at 50%.
