Note: Descriptions are shown in the official language in which they were submitted.
CA 02368323 2002-O1-17
Dental materials based on metal oxide clusters
The invention relates to dental materials based on
polymerizable metal oxide clusters.
Polymerizable compositions are known which, in addition to
organic monomers, also contain poiymerizable metal
compounds.
US 2,502,411 discloses compositions which, in addition to
unsaturated polymerizable organic compounds, contain a
zirconium acrylate which is obtainable by reacting a water_-
soluble zirconium salt with a salt of (meth)acrylic acid.
The zirconium compound is said to improve 'the wettability
of ceramics, metals and cellulose. Details of the structure
of the zirconium acrylates are not given.
DE 3I 37 $40 C2 discloses crystalline zirconium
methacrylate of the general formula Zr4{MAS)~oOzX,(H20)Z_4 in
which MAS is the anion of methacrylic acid and X an anion
from the group hydroxide, alkoxide, halide and carboxylate.
The compounds are said to be suitable as cross-linking
agents in the preparation of vinyl polymers by radical
polymerization of vinyl monomers.
Schubert et al., Chem. Mater 4 (1992) 291 describe the
preparation and characterization.of methacrylate-modified
titanium and zirconium alkoxides which are obtainable by
reaction of the corresponding metal alcoholates with
- CA 02368323 2002-O1-17
methacrylic acid, and Kiclcelbick and Schubert, Chem.
Ber./Recueil 130 (1997) 473, of crystalline oxozirconium
methacrylate clusters of the formulae Zr~ ( OH ) 4O4 ( OMc ) .~~ and
Zr40z ( OMc ) 1z in which OMc is the anion of methacrylic acid
DE 41 33 494 C2 discloses dental resin compositions based
on polymerizable polysiloxanes which are prepared by
hydrolytic condensation of one or more silanes of which at
least one is substituted by a 1,4,5-trioxaspiro-[4,4)-
nonane radical or an ethylenically unsaturated group.
Hydrolyzable and polymerizable silanes are known from DE 44
16 857 Cl which contain one linear or branched organic
radical with at least one C=C double bond and 4 to 50
carbon atoms.
EP I 022 012 A2 and US 6,096,903 disclose dental materials
based on polymerizable and hydrolyzable methacrylate-
modified or oxetane-group-r_ontaining silanes.
Silanes of the type described above can be condensed alone
or together with another hydrolytically condensable
compounds to form inorganic networks, which can then be
cured via the C=C double bonds.contained in the silanes by
ionic or radical polymerization accompanied by the
formation of inorganic-organic networks.
CA 02368323 2002-O1-17
_ j _
The ob;P~t of the invention is to provide dental materials
with improved mechanical properties.
This object is achieved by dental materials which contain
at least one cluster according to the general formula (I-)
~tMl~a~Mz)b~c~~H)dt~R~e~I'-Sp'~-')f~ ~I)
in which
Ml, MZ independently of each other, stand for a metal
atom of the IIIrd or Vth main groups or the Ist
to VIIIth sub-groups of the periodic table;
R is an alkyl group with 1 to 6 carbon atoms;
L is a coordinating group caith 2 to 6 complexing
centres;
Sp is a spacer group or is absent;
Z is a polymerizabl e
group;
a is a number from 1 20;
to
b is a number from 0 10;
to
c is a number from 1 30;
to
d, a independently of eachother, are in each case a
number from 0 to 30;
f is a number from 2 30.
to
The respective values of the indices a to f can vary
according to the type, number and valency of the metals and
ligands. The indices c, d, a and f preferably assume such
- CA 02368323 2002-O1-17
values that the positive charges of the metals M' and M' are
completely equalized and the cluster is neutral. The
cluster can however also be positively or negatively
charged. In this case, the charge of the cluster is
compensated by suitable counterions such as for example Hy,
alkali or alkaline-earth metal ions, NH4+, NR°4+ with R° -
alkyl, in particular C1 to C4 al)cyl, or OH-, R'-C00 with R'
- alkyl, preferably C1 to C1° alkyl, particularly preferably
C1 to C4 alkyl, or halide, preferably F- or C1-. The clusters
(I) have for example a charge of -4 to +4, in particular +1
to +4:
The group L can be chelating or bridging, i.e. the
complexing centres of the group L can be connected to the
same mei.al atom or preferably with two or more different
metal atoms.
The ligand (L-Sp-Z) can be neutral or have a negative
charge. Neutral ligands or ligands with. a single to triple
negative charge are preferred.
The ligands (L-Sp-Z) present in the cluster can be the same
or different. Clusters which contain 1 to 4, preferably 1
or 2 kinds of ligands (L-Sp--Z) are preferred. For example,
two methacrylate ligands can be replaced by allyl
acetoacetate in the cluster Zr40Z(methacrylate)1z. The
resul ting c 1 uster has the formula Zr40z (methacrylate ) 1Z ( allyl
acetoacetate)Z, both'methacrylate and allyl acetoacetate
CA 02368323 2002-O1-17
_ 1 _
being ligands of the type (L-Sp-Z), i.e. the cluster
contains two kinds of ligands of the type (L-Sp-Z).
Clusters which contain only a small proportion of alkoxy
groups (d > e) are preferred. Preferably a _< (a+b),
particularly preferably a = 0.
Preferred definitions, which can be selected independently
of each other, for the individual variables are:
M1, MZ - independently of each other, Ti and/or Zr;
R - an alkyl group with 1 to 4 carbon atoms,
in particular 1 to 2 carbon atoms;
L - a-hydroxycarboxyiate (-CH(OH)-COO ),
cx-aminoc arboxyl ate ( -CH { NHz ) -C00 ) ,
j3-diketonate { [ -C ( -0 ) =CH-C ( =0 ) R'~ ] ; with R~
- alkyl, preferably Ci to C~ alkyl,
particularly preferably Ci to C3 alkyl, in
particular methyl, sulfonate (-S03) or
phosphonate (-P032), particularly
preferably carboxylate (-C00 );
Sp - an alkylene group with 1 to 18 carbon
atoms, an oxyalkylene group with 1 to 18
carbon atoms and 0 to 6 oxygen atoms or an
arylene group with 6 to 14 carbon atoms, the
spacer Sp being able to contain one or more,
preferably 0 to 2 of the groups 0, S, CO-0,
0-C0, CO-NH; NH-C0, 0-CO-NH; NH-CO-0 and NH;
CA 02368323 2002-O1-17
_ ()
particularly preferably, Sp is an alkylene
group with i to 6~ in particular 1 to 3
carbon atoms or' is absent;
Z - an ethylenically unsaturated group, an
epoxide, oxetane, vinyl ether,
1,3-dioxolane, spiroorthoester;
particularly preferably a methacrylic
and/or acrylic group;
a - 2 to 11;
b - 0 to 4.
The values of the indices c, d, a and f again correlate to
the number and charge of the metal atoms. Preferably, they
assume values such that the charge of the cluster is
equalized. Typical values for c are in the case of the
preferred clusters 1 to 1f, in particular 2 to 5, for_ d and
a 0 to 10 and in particular 0 to 8, for f 4 to 20 and in
particular 6 to 15.
According to a particularly preferred version, M1 - Mz.
Clusters in which M1 and ~I' are each zirconium are
particularly preferred.
The polymerizable groups Z are preferably bound to the
metal centres direct or by a short spacer via carboxylate
groups.
CA 02368323 2002-O1-17
- 7 -
Particularly preferred ligands of the type {L-Sp-Z) are
acrylate, methacrylate, oleate, allyl acetoacet.ate and
acetoacetoxyethyl methacrylate.
Particularly preferred clusters are:
Zr6 ( OH ) 404 ( OMc ) 1z i Zr40z ( OMc ) 1z i Zr60z ( OC4H9 ) to ( OMc ) to i
T1b04 ( OCZHS ) 3 ( OMC ) S i T14O2 ( O-~--C3H7 ) b ( OMC ) 6; T1402 ( O-1-
C3H7)6(~MC)6; T190g{OCgH~)4(OMC)16i Zr4T1Z04(OC4H9)2(OMC)14i
ZrzTi404 ( OC4H9 ) b ( OMc ) to i Zr4Ti406 ( OBu ) 4 ( OMc ) 16 and 2, r6Tiz06
( OMc ) zo.
OMc in each case standing for a methacr_ylate group.
Similarly preferred are the clusters which contain acrylate
groups instead of the methacrylate groups.
The clusters according to formula (I) can be prepared by
reacting metal alkoxides with suitable polymerizable
ligands, optionally with the addition of_ water. For
example, the reaction of zirconium{IV)-propoxide (Zr{0-
C3H~)4) with a quadruple molar excess of methacrylic acid
(HOMe) produces dusters of the composition Zr40z(OMc)lz (G.
Kickelbick, U. Schubert, Chem. Ber./Recueil 130 (1997)
473):
4 Zr ( OC3H7 ) 4 + 14 HOMc ~ Zr40z ( OMc ) 1z + 2 C3H~OMc + 14 C3H70H
CA 02368323 2002-O1-17
Moreover, suitable clusters can be prepared by the exchange
of ligands for polymeri~.a.ble ligands. For example, the
reaction of titanium oxide clusters TiaO~ ( OOCRa) ~ with
unsaturated carboxylic acids (HOOCR''') produces clusters of
the compos ition TiaO~ ( OOCRa ) e_a ( OOCRf' ) a . Spec i f ical 1y, the
reaction of the titanium carboxylate cluster
Tib04 ( OCZHS ) 8 ( acetate ) $ with methacrylic acid ( HOMc } produces
the c luster Ti604 ( OCZHS ) s ( acetate ) 8_u ( OMc ) a .
Alternatively, suitable clusters can be obtained by the
derivatization of inorganic clusters. For example, the
reaction of SiW1103~$ with trichloro- or t:riethoxysilanes
RYSiQ3 ( Q = Cl or -OC,HS ) in which RY contains a polymerizable
group produces polymerizable clusters of the composition
SiW11039 ( OSi.2R2) 4
The clusters according to formula (I) represent substances
of high reactivity which can be processed alone or
preferably in combination with other polymerizable
components by polymerization to form mechanically stable
layers, moulded bodies and fillers. These are characterized
by a very small proportion of monomers which can be
dissolved out by solvents and a high stability even in
humid conditions. The mechanical properties of the cured
materials are not impaired by water storage.
For curing; an initiator for ionic or radical
polymerization is preferably added to the polymerizable
CA 02368323 2002-O1-17
clusters or mixtures of the clusters with other
polymerizable components. Depending on the type of
initiator used, the polymerization can be initiated
thermally, by UV or visible light. In addition, the
mixtures can contain further additives, such as for example
colorants {pigments or dyes), stabilizers, flavoring
agents, microbicidal active ingredients, plasticizers
and/or UV absorbers. The clusters according to formula {I~)
and their mixtures are suitable in particular for use as
dental materials or for the preparation of dental
materials. By dental materials are preferably meant
adhesives, coating materials, cements and in particular
filling materials.
The clusters according to formula (I) have only a low
volatility because of their high molecular weight and can
therefore largely be safely processed. Through the size and
structure as well as the number of polymerizable groups of
the clusters, the cross-linking density and thereby the
mechanical properties such as E-modules and strength and
the swelling behaviour in organic solvents of the cured
materials can be selectively set. Size,and structure of the
clusters as well as the number of polymerizable groups per
metal atom can be monitored by variations in the synthesis
parameters. The cluster size and structure are governed by
the ratio of metal oxide to ligand in the- educt mixture,
but also by the nature of the radicals R in the alkoxides
Ml { OR } ~, or MZ ( OR ) n used . Furthermore, the mechanical
CA 02368323 2002-O1-17
properties such as strength and fle::ibility can be
influenced via the distance between the metal centres and
polymerizable radicals, i:e. via the length of the spacer
groups -Sp-.
In the case of the clusters according to formula (I), the
polymerizable groups are fixed to a compact particulate
cluster structure. The result of this is that, upon
polymerization, rigid products with a high cross-linking
density are obtained. The clusters represent three-
dimensional molecules with a defined spatial structure and
size and allow, upon co-polymerization with other
components, an optimum cross-linking density to be set for
the purpose in question. The structure of the clusters
guarantees a complete incorporation of the clusters into
the polymer network. It ensures a uniform environment for
all the polymerizable organic ligands, so that these are
practically equivalent as regards their reaction with
organic co-monomers, which results in a uniform polymer
structure developing around each ligand.
In addition, the abrasiveness or the optical properties
such as for example the refractive index can be varied via
the type and number of metal atoms.
Substances in which the clusters are soluble, i.e. liquid
materials in particular; are preferred as further
polymerizable components. Radically o.r ionically
CA 02368323 2002-O1-17
polymerizable mono- and polyfunctional compounds can
primarily be considered here, in particular polymerizable
organic monomers and silanes and polysiloxanes with
polymerizable groups as well as mixtures of these
compounds.
Ethylenically unsaturated organic monomers, in particular
monofunctional or polyfunctional methacrylates which can be
used alone or in mixtures are preferred as polymerizable
organic monomers. Mono(meth)acrylates such as methyl,
ethyl, butyl, benzyl, furfuryL, phenyl(meth)acrylate,
isobutyl(meth)acrylate, cyclohexyl(meth}acrylate and
polyfunctional (meth)acrylates-such as tetraethylene glycol
di(meth)acrylate, triethylene glycol di(meth)acrylate,
diethylene glycol di(meth)acrylate, ethylene . glycol
di~meth)acrylate; polyethylene glycol di(meth}acrylate,
butanediol di(meth)acrylate, hexanediol di(meth)acrylate,
1,10-decanediol di(meth)acrylate, 1,12-dodecanediol
di(meth)acrylate, bisphenol-A di(meth)acrylate,
trimethylolpropane tri(meth)acrylate, 2,2-bis-4-(3-
methacryloxy-2-hydroxypropoxy)-phenylpropane (bis-GMA),
pentaerythritol tetra(meth)acrylate as well as the reaction
products from isocyanates, in particular di- and/or
triisocyanates, and OH-group-containing (meth)acrylates can
be considered as preferred examples of these compounds.
Examples of these are the reaction products of l mol 2,2,4-
trimethylhexamethylene diisacyanate with 2 mol 2-
hydroxyethylene methacrylate (UDMA) or 2 mol hydroxypropyl
CA 02368323 2002-O1-17
- I? -
met:~acrylate as well as the reaction products of 2 mol
glycerin dimethacrylate with 1 mol 2,2,4-
trimethylhexamethylene diisocyanate, isophoron diisocyanate
or re, a,cx' , cx' -tetramethyl-xylylene-m-diisocyanate . The use
of polyfunctional (meth)acrylates is particularly
preferred. By polyfunctional compounds are meant those with
several polymerizable groups.
Further preferred polymerizable organic monomers are
cationically polymerizable mono- or polyfunctional monomers
such as 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane
carboxylate, bis-(3,4-epoxycyclohexylmethyl)adipate,
vinylcyclohexene dioxide, 3-ethyl-3-hydroxymethyl oxetane,
1;10-decanediylbis(oxymethylene)bis(3-ethyloxetane) and
3,3-(4-xylylenedioxy)-bis-(methyl-3-ethyl-oxetane).
Compounds which have polymerizable groups; preferably
(meth)acryl groups, or rationally polymerizable groups,
preferably epoxide, oxetane, spiroorthoesters or vinyl
ether groups, are particularly suitable as polymerizable
silanes and polysiloxanes. Suitable silanes and
polysiloxanes and their preparation are described in DE 41
33 494 C2, DE 44 16 857 C1, EP 1 022 0?2 A2 and US
6,096,903. Preferred silanes are listed below.
Polysiloxanes based on these silanes are particularly
preferred, the polysiloxanes being able to be present in
the form of the homo- and co-condensates.
CA 02368323 2002-O1-17
- LJ -
Silanes of the general formula (1) are prefeT_red
i
Yinisl X miR 4_(nl-mi) ( ~-)
in which the radicals X1, Y1 and Rl are the same or different
and haves the following meanings:
R1 - alkyl, alkenyl, aryl, alkylaryl or arylalkyl,
X1 - hydrogen, halogen, hydroxy, alkoxy, acyloxy,
alkylcarbonyl, alkoxycarbonyl or DTRsz with RS -
hydrogen, alkyl or aryl,
Y1 - a substituent which contains a substituted or
unsubstituted 1,4,6-trioxaspiro-[4,4]-nonane
radical,
n1 - 1, 2 or 3,
ml - l, 2 or 3, with n1 + mi <_ 4,
and silanes of the general formula (2),
fXlnlRlltls~-[RZ(Al)1]4-(nl+ki)~~iBl (2)
in which radicals Ai, R1, RZ and X1 are the same or different
and have the following meanings:
AI - 0, S, PRE, PORE, NHC ( 0 ) 0 or NHC ( 0 ) ONRE,
with RE - hydrogen, alkyl or aryl,
B1 - a linear or branched organic radical which is
CA 02368323 2002-O1-17
-1=J-
derived from a compound B-~ with at least one ( for
1 - l and A = NHC(0)0 or NHC(0)NR') or at least
two C=C double bonds and 5 to 50 carbon atoms,
with R~ = hydrogen, alkyl or aryl,
Rl - alkyl, alkenyl, aryl, alkylaryl or arylalkyl,
RZ - alkylene, arylene or alkylene arylene,
X1 - hydrogen, halogen, hydroxy, alkoxy, acyloxy,
alkyicarbonyl, alkoxycarbonyl or NR~Z with R° -
hydrogen, alkyl or aryl,
n1 - l, 2 or 3,
k1 - 0, 1 or 2,
1 - 0 or 1,
X1 - an .integer the maximum value of which
corresponds to the number of double bonds in the
compound Bl minus 1 or is equal to the number of
double bonds in the compound B1 when 1 = 1 and A
stands for NHC(0)0 or NHC{0)ONR'.
The silanes of the general formula (1) and (2) are
hydrolyzable and polymerizable, the radicals Xi being
hydrolyzable and the radicals Bl and Yi being polymerizable
and in each case at least one radical B1, X~ and Yi with the
above-named meaning being present in the silanes of the
general formula {1} and (2). Polysiloxanes based on silanes
{1) and/or {2) are preferred polymerizable components.
The alkyl radicals of the compounds ( 1 ) and ( 2 } are a . g .
linear, branched or cyclic radicals with 1 to 20~,
CA 02368323 2002-O1-17
_ j i _
preferably 1 to 10 carbon atoms, and Lower alkyl radicals
with 1 to 6 carbon atoms are particularly preferred.
Special examples are methyl, ethyl, N-propyl, i-propyl, n-
butyl, s-butyl, t-butyl, i-butyl, n-pentyl, n-hexyl,
cyclohexyl, 2-ethylhexyl, dodecyl and octadecyl.
The alkenyl radicals are e.g. linear, branched or cyclical
radicals with 2 to 20, preferably 2 to 10 carbon atoms and
lower alkenyl radicals with 2 to 6 carbon atoms such as
e.g. vinyl, allyl or 2-butenyl are particularly preferred.
Preferred aryl radicals are phenyl, biphenyl and naphthyl.
The alkoxy, acyloxy, alkylcarbonyl, alkoxycarbonyl and
amino radicals are preferably derived from the above-named
alkyl and aryl radicals: Special examples are methoxy,
ethoxy, n- and i-propoxy, n-, i-, s- and t-butoxy,
methylamino, ethylamino, dimethylamino, diethylamino, N-
ethylanilino, acetyloxy, propionyloxy, methylcarbonyl,
ethylcarbonyl, methoxycarbonyl, ethoxycarbonyl, benzyl, 2-
phenylethyl and tolyl.
The radicals named can optionally have one or more
substituents; e.g. halogen, alkyl, hydroxyalkyl, alkoYy.,
aryl, aryloxy,. alkylcarbonyl, alkoxycarbonyl, furfuryl,
tetrahydrofurfuryl, amino, alkylamino, dialkylamino,
trialkylammonium, amido, hydroxy, formyl, carboxy,
mercapto, cyano, isocyanato, nitro, epoxy, S03H and P04H2.
CA 02368323 2002-O1-17
- l~ -
Of the halogens, fluorine, chlorine and bromine are
preferred.
The substituted or unsubstituted 1,4,6-trioxaspiro[4,4]-
nonane groups are bound to the Si atom via alkylene or via
alkenylene radicals which can be interrupted by ether or
ester groups.
Further preferred are silanes according to the general
formula (3) as well as polysiloxanes based on same
2 2 1 3 S Z 6
B fA -~Z. )dl'R -IR -S1X a1R bl}cl
R4
in which the radicals and indices have the following
meanings:
Bz - a linear or branched organic radical with at
least one C=C double bond and 4 to 50 carbon
atoms;
XZ - hydrogen, halogen, hydroxy, alkoxy, acyloxy,
alkylcarbonyl, alkoxycarbonyl or NR'z;
R6 - alkyl, alkenyl, aryl, alkylaryl or arylalkyl;
R$ - alkylene, arylene, arylenealkylene or
alkylenearylene with in each case 0 to 10 carbon
atoms, these radicals being able to be
interrupted by oxygen and sulphur atoms or by
amino groups;
R' - hydrogen, alkyl or aryl;
AZ - 0, S or NH for di - Z and Z1 - CO
CA 02368323 2002-O1-17
_ j% _
and R3 - al)cylene, arylene or a7 kylenearylene
with in each case 1 to 10 carbon a oms, these
radicals being able to be interrupted by oxygen
and sulphur atoms or by amino groups, and R'' -
COOH; or
A2 - 0, S or NH for d1 - 1 and Z1 - CO
and R3 - alkylene, arylene or a7_kylenearylene
with in each case I to 10 carbon atoms, these
radicals being able to be interrupted by oxygen
and sulphur atoms or by amino groups, and R~ - H~;
or
AZ - 0, S, NH or C00 for dl - 1 and Z1 - CHR~,
with R~ equal to H, alkyl, aryl or alkylaryl, and
R3 - alkylene, arylene or allcylenearylene with
in
each case 1 to 10 carbon atoms, these radicals
being able to be interrupted by oxygen and'
sulphur atoms or by amino groups, and R4 - OH; or
AZ - O, S, NH or COO for dl - 0 and R3 - alkylene,
arylene or alkylenearylene with in each case 1to
10 carbon atoms, these radicals being able to be
interrupted by oxygen and sulphur atoms or by
amino groups, and R4 - OH; or
AZ - S for dl - 1 and ZZ - CO and R3 - N and Rl' - H;
al - 1, 2 or 3;
b1 - 0, 1 or 2;
a1+bl - 3l
c1 - 1, 2, 3 or 4.
The silanes of the formula (3} are polymerizable via the
radicals ~~ and hydrolyzable via the radicals XZ.
The optionally present alkyl, alkenyl, aryl, alkoxy,
acyloxy, alkylcarbonyl, aI)coxycarbonyl and amino radicals
have the meanings defined for the formulae (1} and (2).
For al >_ 2 or b~ - 2, the radicals YZ and R' can in each case
have tile Same or a different,meaning. The radical BZ is
CA 02368323 2002-O1-17
- 1S -
derived from a substituted or unsubstituted compound
B'(A-H)~1 with at least one C=C double bond, such as a.g.
vinyl, alkyl, acryl and/or rnethacryl groups and 4 to 50,
preferably 6 to 30 carbon atoms. Preferably, B' is derived
from a substituted or unsubstituted compound with two or
more acrylate or methacrylate groups. Such compounds are
also called (meth)acrylates. If the compound B~(AZH)~; is
substituted, the substituents can be selected from the
substituents named above. The group AzH can be -OH, -SH,
-NHZ or -COOH and c can assume values from 1 to 4.
Silanes according to formula (4} and polysiloxanes based on
them are particularly preferred
[ (Wq-R13 ZZ)P_Rlo]mZY2-R9-S1X3n2R83-n2 Formula (4}
in which
X3 stands for.a halogen atom, a hydroxyl, alkoxy andlor
acyloxy group;
n2 is equal to 1 to 3;
R8 stands for an alkyl, alkenyl, aryl, alkylaryl,
arylallcyl group;
R9 stands for an alkylerie group;
R1° stands for a p-times substituted, linear, branched or
cyclic, saturated or unsaturated, aromatic or
aliphatic organic radical with 2 to 40 carbon atoms
and optionally 1 to 6 heteroatoms;
R13 stands for a q-times substituted.linear, branched or
cyclic organic radical with 1 to 20 carbon atoms or is
absent;
p is equal to 1 or 2;
q is equal to 1 to 6;
Y2 stands for -NR11-; N or -(C=0)-NH-;
m2 is equal to 2 for YZ - N and equal to 1 for -Y -
-NR11- or -( C=0 } -NH-;
R11 stands for an alkyl or aryl group;
CA 02368323 2002-O1-17
_ 'I <) _
Z~ stands for 0, S, -(C=0)-0-, -(C=0)-NH-, -0-(C=0)-P1H-
or is absent;
W stands for CH,=CR~~ -{ C=0 ) -0-; and
RlZ stands for a hydrogen atom or an alkyl group.
Suitable heteroatoms are phosphorus and preferably oxygen.
In connection with formula {4), by alkyl, acyloxy, alkoxy,
alkenyl groups and allcylene groups are meant radicals which
preferably contain 1 to 25 carbon atoms, particularly
preferably 1 to 10 carbon atoms and quite particularly
preferably 1 to 4 carbon atoms and optionally bear one or
more substitutes such as for example halogen atoms, nitro
groups or alkyloxy radicals. By aryl is meant radicals,
groups or substituents which preferably have 6 to 10 carbon
atoms and can be substituted as stated above. The above
definitions also apply to composite groups such as for
example alJcylaryl and arylalkyl groups . An aJ_l~ylaryl group
thus designates for example an aryl group as defined above
which is substituted with an alkyl group as defined above.
The alkyl, acyloxy, alkoxy, alkenyl groups and alkylene
groups can be linear, branched or cyclical.
Preferred definitions, which can be selected independently
of each other, for the individual variables of formula (4)
are:
X3 - a methoxy and/or ethoxy croup;
n2 - 2 or 3;
R$ - a C1 to C3 alJcyl group, in particular a methyl
group;
R9 - a C1 to C4 alkylene group;
R1° - a p-times substituted linear, branched or
cyclic, saturated or unsaturated, aromatic or
aliphatic organic radical with 2 to 10 carbon
atoms and optionally a hetero atom, preferably an
CA 02368323 2002-O1-17
-ii) _
oxygen atom, particularly preferably a Ci to C~,
alkenylene radical or a manocyclic radical with
4 to 10, in particular 5 to 8 carbon atoms;
R'' - a q-times substituted linear, branched or
cyclical organic radical with 1 to 4 carbon
atoms, particularly preferably a Ci to C3 alkylene
radical;
p - 1 or 2, in particular l;
q - 1 or 2;
Yz - N or -(C=0)-NH-;
Zz - -(C=O)-; and/or
R1z - a hydrogen atom or a methyl group.
Hydrolyzable and polymerizable oxetane silanes according to
the general formula (5) and their stereoisomers as well as
polysiloxanes based thereon are further preferred:
(5~ _
/ \R16 R15 { R1~ SiX~R~? }
2
a Y :_a_~~ ~2
the variables R14 Rls Ri6 R:.7 Ris R'g Rzo ~l~ Ys az bz
1. , I I l 1 1 1 P 1 1
cz, and xz, unless otherwise stated, having the following
meanings independently of each other:
R14 - hydrogen or substituted or unsubstituted C1 to
C,o alkyl;
Rls - absent or substituted or unsubstituted
C1 to Cls alkylene, C6 to Cls arylene, C~ to Cls
alkylenearylene or arylenealkylene, these
radicals being able to be interrupted by at least
one group selected from ether, thioether, ester,
carbonyl, a~iide and urethane group;
R16 - absent or substituted or unsubstituted .
C1 to Cis alkylene, C6 to Cls arylene, C7 to Cls
alkylenearylene or C7 to Cls arylenealkylene,
, CA 02368323 2002-O1-17
these radi cals being able to be i nt~rrupted by at
least one group selected from ether, thioether,
ester, thioester, carbonyl, amide and urethane
group or bear these in terminal position;
R~' - absent or substituted or unsubstituted
Cl to C1$ alkyl, Cz to Cls alkenyl, C~ to C1$ aryl,
C~ to C1$ alkylaryl or C~ to Clg arylalkyl, these
radicals being able to be interrupted by at least
one group selected from ether, thioether, ester,
carbonyl, amide and urethane group;
R1$ - absent or substituted or unsubstituted
-CHRzo-CHRz°-, -CHRzo-CHRzo-S-R19-, -S-R19-, -Y3-CO-
NH-R19- or -CO-0-R19-;
R19 - substituted or unsubstituted C1 to C1$ alkylene,
C~ to Cls arylene, C~ to C18 alkylenearylene or C6
to C1$ arylenealkylene, these radicals being able
to be interrupted by at least one group selected
from ether, thioether, ester, carbonyl; amide and
urethane group;
~~zo - hydrogen or substituted or unsubstituted C1 to
C1$ alkyl or C6 to Clo aryl;
X'' - a hydrolyzable group, namely halogen, hydroxy,
allcoxy or acyloxy;
Y3 - 0 or S; '
az - 1, 2 or 3 ;
bz - l, 2 or 3;
c2 - 1 to 6; and
x2 - 1, 2 or 3;
and on condition that ( i ) az+xz - 2 , . 3 or 4 and ( ii ) az
and/or b2 - 1.
However, the above formulae cover only such compounds which
are compatible with the doctrine of valence.
Normally, the silanes according to formula (5) are present
as stereoisomer mixtures and in particular as racemic
compounds.
CA 02368323 2002-O1-17
The ether, thioether, ester, thioester, carbonyl, amide and
urethane groups possibly present in the case of the
radicals of formula (5) are defined by the following
formulae: -0-, -S-, -CO-0-, -0-CO-, -CO-S-, -S-CO-, -CS-0-,
-0-CS-, -CO-, -CO-NH-, -NH-CO-, -0-CO-NH- and -NH-CO-0-.
The non-aromatic radicals or non-aromatic parts of the
radicals which can be present in formula (5) can be linear,
branched or cyclic.
In the silanes according to formula (5), any alkyl radicals
present have preferably I to 8 and particularly preferably
1 to 4 carbon atoms. Special examples of possible alkyl
radicals are methyl, ethyl, n- and iso-propyl, sec.- and
tert.-butyl, n-pentyl, cyclohexyl, 2-ethylhexyl and
octadecyl.
In the silanes according to formula (5), any alkenyl
'radicals present have preferably 2 to 10 and particularly
preferably 2 to 6 carbon atoms. Special examples of
possible alkenyl radicals are vinyl, allyl- and iso-
butenyl.
Preferred examples of possible aryl radicals of the formula
(5) are phenyl, biphenyl and naphthyl. Alkoxy,radicals have
preferably l to 6 carbon atoms. Special examples of
possible alkoxy radicals are methoxy, ethoxy, n-propoxy,
iso-propoxy and tert.-butoxy. Acyloxy radicals have
preferably 2 to 5 carbon atoms. Special examples are
acetyloxy and propionyloxy.
Preferred alkylene radicals of formula (5) are derived from
the above preferred alkyl radicals, and preferred arylene
radicals are derived from the above preferred aryl
radicals. Preferred radicals which consist of a combination
of a non-aromatic and aromatic part are derived from the
CA 02368323 2002-O1-17
above preferred alkyl and aryl radicals. Special examples
of this are benzyl, 2-phenylethyl and tolyl.
The named substituted R radicals of formula (5) bear one or
more single substituents. Examples of these substituents
are methyl, ethyl, phenyl, benzyl, hydroxymethyl,
hydroxyethyl, methoxy, ethoxy, chlorine, bromine, hydroxy,
mercapto, isocyanato, vinyloxy, acryloxy, methacryloxy,
allyl, styryl, epoxy, carboxyl, S03H, P03Hz or P04HZ.
For a2, bZ, cZ or x2 ? 2, the radicals X4 as well as the
individual R.radicals can in each case have the same or a
different meaning.
In addition, preferred definitions exist for the variables
of formula (5) set out above which, unless other~iise
stated, can be selected independently of each other and are
as follows:
R1'' hydrogen or C1 to CS allcyl;
-
R15 C1 to Cs alkylene, these radicals being able to
-
be interrupted by at least one group selected
from ether, thioether, ester and urethane group;
R16 absent or C1 to Cs alkylene, these radicals being
-
able to be interrupted by at least one group
selected from ether, thioether, ester, thioester,
carbonyl, amide and urethane group or bear these
in terminal position;
Rl' absent or methyl, ethyl or phenyl;
-
R1$ absent or -CHRZ-CHRZ-, -S-P.19-,
-
-Y-CO-NH-R19- or --CO-0-R19-;
R19 C1 to Cs allcylene, these radicals being able to
-
be interrupted by at least one group selected
from ether, thioether, ester, carbonyl, amide and
urethane group;
R2 hydrogen or C1 to CS alJcyl;
-
X4' methoxy, ethoxy or chlorine;
-
CA 02368323 2002-O1-17
Y~ - 0 or S ;
a- - 1;
'.~ z - 1
c2 - 1 to 6;
xz - 2 or 3; and/or
az+xZ - 3.
The individual R radicals can in turn bear single
substituents.
Preferred compounds according to formula (5) are
accordingly those for which at least one of the variables
of formula (5) meets the preferred definition described
above.
Furthermore, oxetane silanes of formula (5) are preferred
for which the indices az, b' and/or c' have the value 1.
The silanes (5) are polymerizable via the oxetane groups
and hydrolyzable via the radicals X4.
The above-named silanes can be processed, either alone or
together with other hydrolytically condensable compounds of
silicon, aluminium, zirconium, titanium, boron, tin,
vanadium and/or phosphorus to form polysiloxanes. These
additional compounds can be used either per se or already
in pre-condensed form.
Preferred further hydrolytically compounds of silicon are
silanes of the general formula (6)
Rzi~.z( z3Rzz)msSiX54-n;.z+m3) Formula ( 6 )
in which
CA 02368323 2002-O1-17
R-1 stands for a C, to Cs alkyl, C, to C-= all~enyl or C~ to
Ci4 aryl group;
R" stands for a C1 to C$ al)cylene, Cz to Ci~ al)cenylene or
C6 to C1,, arylene group;
XS stands for a hydrogen or halogen atom or a Ci to Cs
alkoxy group;
Z3 stands for a glycidyl, acryl, methacryl, vinyl, allyl
or vinylether group
k2 is equal to 0, l, 2 or 3;
m3 is equal to 0, l, 2 or 3; and
k2+m3 is equal to 0, l, 2 or 3.
Preferred definitions, which can be selected independently
of each other, for the individual variables are:
R21 - a C1 to C3 alkyl, Cz to C5 alkenyl or a phenyl
group;
a C1 to CS alkylene, CZ to C5 al)cenylene or a
phenylene group;
XS - a halogen atom, a methoxy or ethoxy group;
Z3 - an acryl or methacryl group;
lcz - 0 and 1;
m3 - 0 and 1;
k2+m3 - 0, l or 2.
Such silanes are described for example in DE 34 07 087 A1.
Preferred zirconium, titanium compounds for the co-
condensation with the named silanes are those according to
formula (7)
MeX6yRz3Z Formula ( 7 )
in which
Me stands for Zr or Ti;
CA 02368323 2002-O1-17
R'3 stands for a hydrogen atom, a substituted or
unsubstituted C_ to C1~ alkyl, Ci to C15 alkylaryl or C~
to C1~ aryl group;
X6 stands for a halogen atom, a hydroxyl or C1 to C8
alkoxy group;
Y is equal to 1 to 4;
z is equal to 0 to 3.
Preferred definitions, which can be selected independently
of each other, for the individual variables are:
Rz3 - a C1 to C5 alkyl or a phenyl group;
X6 - a halogen atom, a methoxy, ethoxy or propoxy
group;
y - 4;
z - 0 or l, in particular 0.
Particularly preferred zirconium and titanium compounds are
ZrCl4, Zr(OCZHS)4, Zr(OC3H7)4, Zr(OC4H9)4, ZrOClz, TiCl4,
Ti ( OCZHS ) 4, Ti ( OC3H7 ),, and Ti ( OC4H~ ) 4 .
Preferred aluminium compozznds are those according to
formula (8)
AlRZ43 Formula ( 8 )
in which
R24 stands for a halogen atom, a hydroxyl or C1 to C$
alkoxy group, preferably for a halogen atom or a C, to
C; alkoxy group.
Particularly preferred aluminium compounds are Al(OCH3)3,
A1 ( OCzH~ ) 3, A1 ( OC3H7 ) 3, Al ( OC4H9 ) 3 and AlCl3 .
CA 02368323 2002-O1-17
'' ; _
In addition, boron trihalides, tin tetra.halides, tin
tetraalkoxides and/or vanadyl compounds are suitable for
co-condensation with the above-named silanes.
The curing of the materials takes place, depending on the
initiator used, by thermal, photochemical or redoY-induced
polymerization. , ,
Peroxides, in particular dibenzoyl peroxide, dilauroyl
peroxide, tert.-butyl peroctoate and tert.-butyl
perbenzoate are preferred as initiators for the hot-curing
systems. Tn addition, azobisisobutyroethylester, 2,2'-
azobisisobutyronitrile {AIBN}, benzopinacol and 2,2'-
dialkylbenzopinacols are suitable.
Radical-supplying systems, for example benzoyl peroxide,
lauroyl peroxide or preferably dibenzoyl peroxide, together
with amines such as N,N-dimethyl-p-toluidine, N;N-
dihydroxyethyl-p-toluidine, N,N-dimethyl-sym.-xylidine °or
other structurally-related amines are used as initiators
for cold polymerization. Amine and peroxide are usually
distributed over two different components of the dental
material. Upon mixing of the amine-containing base paste
with the peroxide-containing initiator paste, the radical
polymerization is initiated by the reaction of amine and
peroxide.
Benzophenone and its derivatives as well as benzoin arid its
derivatives can be used for example as initiators for
photopolymerization. Further preferred photoinitiators are
the a-dil:etones such as 9,10-phenanthrenquinone, diacetyl~,
furil, anisil, 4,4'-dichlorobenzil and 4,4'-dialkoxybenzil.
Camphorquinone and 2,2-methoxy-2-phenyl-acetophenone and in
particular cx-diketones in combination wiyth amines as
reduction agents are particularly preferably used.
Preferred amines are 4-(N,N-dimethylamino}--benzoic acid
ester, N,N-dimethylaminoethyl methacrylate, N,N-dimethyl-
CA 02368323 2002-O1-17
sym.-xylidine and triethanolamine. In addition, acyl
phosphines such as e.g. 2,4,6-trimethylbenzoyldipher~yl- or
bis-(2,6-dichlorobenzoyl)-4-N-propylphenylphosphinic oxide
are also particularly~suitable as photoinitiators.
For curing cationically polymerizable systems, diaryl-
iodonium or triarylsulfonium salts such as e.g.
triphenylsulfonium hexafluorophosphate or hexafluoro-
antimonate are particularly suitable as well as the
photoinitiator systems described in X10 96/13538 and WO
98/47047.
Furthermore, the mixtures can be filled with organic or
inorganic particles or fibres to improve the mechanical
properties. In particular; amorphous, spherical materials
based on mixed oxides of SiO~, ZrO~ and/or Ti02 with a mean
average particle size of 0.005 to ?.0 Vim, preferably from
0.1 to 1 Vim, as disclosed for example in DE-PS 32 47 800,
microfine fillers such as pyrogenic sili_cic acid ~or
precipitation silicic acid as well as macro- or mini-
fillers, such as quartz, glass ceramic or glaas powder with
an average particle size of 0.01 to 20 Vim, preferably 0.5
to 5 ~cm as well as x-ray-opaque fillers such as ytterbium
fluoride, are suitable as filler components. By mini-
fillers are meant fillers with a parti cle s ize of 0 . 5 to
1.5 Vim, and by macro-fillers fillers with a particle size
of l0 to 20 Vim.
Preferred compositions according to the invention contain,
relative to their overall mass:
(a) 5 t~ 90% wt.-%, in particular 5 to 40 wt.-%, quite
particularly preferably 10 to 20 wt.-% of one or more
clusters according to formula (I),
(b) 10 to 90 wt.-o, in particular 10 to 80 wt.-% of one or
more further polymerizable components,
CA 02368323 2002-O1-17
(c) 0.1 to 5.0 wt.-%, in particular 0.2 to 2.0
polymerization initiator,
and
(d) 0 to 90 wt.-%, in particular 0 to 80 wt.-% filler.
The above composition can be further optimized in
accordance with the desired use. Thus, a material which is
particularly suitable as dental filling material preferably
contains, in each case relative to the overaJ_l mass of the
material:
( a ) 5 to 20 % wt . - % of one or more clusters according to
formula (I),
(b) 0 to 20 wt.-% of one or more further polymerizable
components,
(c) 0.2 to 2.0 wt.-% 2.0 polymerization initiator,
and
(d) 5 to 80 wt.-% filler.
A dental material which is particularly suitable as dental
cement preferably contains, in each case relative to the
overall mass of the material:
( a ) 5 to 30 % wt . - % of one or more clusters according to
formula (I),
(b) 0 to 30 wt.-% of one or more further polymerizable
components,
(c) 0.2 to 2.0 wt.-% 2.0 polymerization initiator,
and
(d) 5 to 50 wt.-% filler.
A dental material which is particularly suitable as dental
coating material preferably contains, in each case relative
to the overall mass of the material:
( a } 5 to 40 % wt . - % of one or more clusters according to
formula ( I } ,
CA 02368323 2002-O1-17
- .i() -
{b) 5 to 80 wt.-~ of one or more further polymerizable
components,
{c) 0.2 to 2.0 wt.-% 2.O polymerization initiator,
and
(d) 0 to 40 wt.-% filler:
Quite particularly preferred are materials which contain,
as further polymerizable component (b), 10 to 90 wt.-
polysiloxane and 0 to 40 wt.-o polymerizable organic
monomers, in each case relative to the overall mass of the
dental material.
These compositions are particularly suitable as dental
materials, quite particularly as adhesives, for example for
inlays, coating materials, cements and in particular
filling materials. In general, the compositions are
particularly suitable for those uses in which the curing of
the material takes place in the mouth cavity.
After polymerization, the dental material. s according to the
invention have only a minimal content of unpolymerized
constituents which can be dissolved out with aqueous or
alcoholic solvents, which represents a significant
improvement vis-a-vis conventional dental materials, as
toxic side effects caused by monomeric constituents are
suppressed.
According to the invention, clusters of a defined size and
structure, i.e. pure, defined compounds of a known
stoichiometry, are used for the preparation of dental
materials, particularly preferably clusters with
monodispersed mass distributiorx. In this way, the material
properties of the dental materials, such as for example E-
modulus, strength, hardness and abrasivity, can be set and
improved in a controlled manner. Dental materials which
contain 1 to 2 different.clusters are preferred.
CA 02368323 2002-O1-17
In the following, the invention is explained in more detail
using examples.
Example l:
Synthesis of the oxozirconium methacrylate cluster of
composition Zr,,02( OMc ) 12
2.04 g (24 mmol) methacrylic acid were added to 1.73 g (3.6
mmol) of an 80% solution of zirconium butylate (Zr{OC4H9)4)
in n-butanol. The reaction mixture was left to stand for a
day at room temperature and the formed precipitate filtered
off accompanied by the exclusion of moisture. I.09 g {86%
yield) of colourless cubic crystals resulted, which are
soluble in chloroform, ethanol or toluene.
Example 2:
Synthesis of matrix substances based on silicic acid
polycond.ensate
A) Hydrolytic condensation of bis[(methacryloyloxy)pro-
poxycarbonylethyl)-[3-{triethoxysilylpropyl))amine:
16.1g(26mmo1)bis[(methacryloyloxy)propoxy-carbonylethyl)-
[3-(triethoxysilylpropyl)]amine which is obtainable by
Michael addition of 3-aminopropyltriethoxysilane to 2-
(acryloyloxyethyl)-propyl methacrylate (cf. ~P 1 022 022)
were dissolved in 37.5 ml anhydrous ethanol and
hydrolytically condensed accompanied by the addition of
2.81 g of an aqueous O.i N ammonium fluoride solution.
After 24 h stirring at room temperature, the volatile
components were removed in vacuum and approx. 12 g of a
relatively low-viscosity resin (SG-'1) with a viscosity of
c = ca. 8 Pas {23°C) remained. This and all other viscosity
data, unless otherwise stated, involves the rotation
viscosity measured with a rotation rheometer with a
CA 02368323 2002-O1-17
_ j'7 _
paralle?-plate measuring system, CV = 120 (model CVO 120 of
the company Bohlin).
B) Hydrolytic condensation of (3-triethoxysilyl-
propylaminocarbonyl)butyric acid-(1,3{2)-bismethacryl-
oyloxypropyl)ester:
10.9 g (20 mmol) {3-triethoxysilylpropylamido)butyric acid-
(1,3-(2)-bismethacryloyloxypropyl)ester, which was obtained
by amidation from 3-aminopropyltriethoxysilane with the
adduct from glycerin dimethacrylate and glutaric acid
anhydride ( cf . EP 1 022 012 ) , were dissolved in 98 . 2 mol
anhydrous ethyl acetate and hydrolyticaJ_ly condensed
accompanied by the addition of 1.08 g 0.5 N hydrochloric
acid. After 30 minutes' 'stirring at 40°C, the volatile
components were removed in vacuum. The resin obtained was
then silylated after dissolving in a mixture of 35 g tert.-
butylmethyl-ether, 12 g THF and 1.45 g {12 mmol) 2,4,5-
trimethylpyridine by the dropwise additi_,on of 1 .96 g ( 18
mmol) trimethyichlorosilane. After st:L.r~rzng overnight at
room temperature, the reaction mixt~.~re was washed with
diluted hydrochloric acid and saturated NaCl solution and
then dried over anhydrous sodium sulphate. After the
evaporation of the solvent in vacuum, ca. 6 g of a viscous
resin {SG-2} with a viscosity of r~ - ca. 75 Pas {23°C)
remained.
Example 3:
Preparation of dental materials based on clusters according
to example 1 '
various materials were prepared starting from the cluster
Zr40z { OMc ) 1Z from example 1 and the matrix substances ST-1
and SG-2. The clusters were mixed with the matrix
substances as 10% solution in ethanol and the solvent
evaporated off in vacuum after the addition of the
CA 02368323 2002-O1-17
initiator components. The compositions (mass o) of the
thus-prepared unfilled materials M-1 to M-5 are listed in
Table 1. To determine the mechanical properties, testpieces
with the dimens ions 2 5 x 2 x 2 mm were prepared from the
compositions and cured by illumination with light of a
wavelength of 390 to 500 nm (6 minutes). For this purpose,
a dental radiation source~ of the Spectramat type from
Vivadent was used. The bending strength (BS) and the
bending E-modulus (BEM) were determined according to the
ISO standard 4049 (2000), the testpieces having been
previously stored in water at 37°C for 24 h. In addition,
BS and BEM values were also measured for samples which were
stored dry for 24 h at 37°C.
Table 1: Composition (mass %) of the unfilled materials M-
1 to M-5
M-1* ) M-2 M-3* M-4 M_,-5
)
9s.7 8s.7 _ -
SG-2 - - 98.7 88.7 78.7
Zr-Cluster from - 10.0 - 10.0 20
Example 1
Photoinitiatora~ 1.3 1.3 1.3 1.3 1.3
*) Comparison example without clusters
A mixture of 0.3o camphorquinone, 0.6% 4-(N,N-
dimethylamino)-benzoic acid ethyl ester and 0.40
acryl phosphinic oxide (Lucerin TPO, BASF) was
used as photoinitiator
Table 2 : Bending strength ( BS ) and Bending E-modulus ( BEM)
of materials M-1 to M-5
CA 02368323 2002-O1-17
M-1* ~ 1"1-2M-3~ ~_.4 I M-5
) )-
i
Dry BF {MPa) 46 47 48 59 70
- I
HZO storage BS (MPa) 31 52 36 60 60
Dry BEM (MPa) 1230 1900 1820 2100 2400
HZO storage BEM -(MPa) 1000 1920 1750 2270 2600
*) Comparison example without clusters
To prepare the composite pastes C-1 to C-5, the unfilled
materials'M-l to M-5 were mixed with the quantities of
filler given in Table 3. Silanized pyrogenic silicic acid
with an average primary particle size of 40 nm and a BET
surface of 50 mz/g (silanized Aerosil 0~-50, Degussa),
ytterbium trifluoride with an average particle size of 5 ~m
and a BET surface of < 7.5 m'/g (.YbF3, Auer Remy), silanized
SiOZ-ZrOz mixed oxide with a primary particle size of 130 to
230 nm (Spharosil, Tokoyma Soda} and silznized barium
silk ate glass (Ba-Si glass} with an average particle size
of 1.2 ~m were used as fillers. The filler components are
incorporated by means of a capsule vibrator.
The bending strength and the bending E-modulus were then
measured, in each case after 24-hour storage in water or in
the dry. The results are summarized in Table 4.
Table 3: Composition of the composite pastes C-1 to C-5
(values in mass o)
CA 02368323 2002-O1-17
R-1*) Y-2 K-3*) K-4 ~ IC-5
I.
Unfilled ma- 25.0 25.0 25.0 25.U 25.0
terial (M-1) (M-2) (M-3) {M-4) (M-5}
Aerosi:l OX-50 1.0 1.0 1.0 1.0 1.0
YbF3 15.0 15.0 15.0 15.0 15.0
Spharosil 15.0 15.0 15.0 15.0 15.0
i
Ba-Si glass 44.0 44.0 44.0 44.0 44.0
*) Comparison example without clusters
Table 4: Bending strength (BS) and bending E-modulus (BEM)
of the composites C-1 to C-5
IZ_1* R_2 K_3* K_4 R-5
Dry BS (MPa) 94 96 89 101 103
HBO storage BS {MPa)' 68 100 89 110 113
Dry BEM (MPa) 6400 8900 8150 9100 9840
H20 storage BEM (MPa) 5500 9300 7160 9750 1.0900
*) Comparison without dusters
The results show (Tables 2 and 4) that the addition of
clusters of the composition Zr402(OMc)iz in each case leads
to an improvement in strength and to an increase in E-
modulus of the materials. In addition, in the case of the
cluster-containing materials, an increase in the E-modulus
after water storage can be observed, whereas the E-rnodulus
CA 02368323 2002-O1-17
_i(~ -
decreases in the case of the non-modified samples M-1/C-1
and M-3/C-3 after water storage.
Samples of the cured composites C-2 and C-4 were crushed
and the fragments dispersed in ethanol at 37°C. After 72 h,
the solid constituents were filtered off and the filtrate
concentrated to dryness. Almost no residue resulted, which
indicates a complete incorporation of the polymerizabie
components into the polymer network of the composite
matrix.
