U.S. patent application number 14/122792 was filed with the patent office on 2014-04-10 for silicic acid (hetero) polycondensates comprising organically polymerisable groups and either sulphonate groups or sulphate groups, organic polymerisates produced therefrom, and a method for producing said polycondensates.
This patent application is currently assigned to Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung e.V.. The applicant listed for this patent is Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung e.v.. Invention is credited to Somchith Nique, Mona Seyfried, Herbert Wolter.
Application Number | 20140100349 14/122792 |
Document ID | / |
Family ID | 46148877 |
Filed Date | 2014-04-10 |
United States Patent
Application |
20140100349 |
Kind Code |
A1 |
Wolter; Herbert ; et
al. |
April 10, 2014 |
Silicic Acid (Hetero) Polycondensates Comprising Organically
Polymerisable Groups and Either Sulphonate Groups or Sulphate
Groups, Organic Polymerisates Produced therefrom, and a Method for
Producing said Polycondensates
Abstract
The invention relates to silicic acid (hetero) polycondensates
consisting of at least one silane that has a group bonded to
silicon by a carbon atom and that carries an organically
polymerisable C.dbd.C double bond, and at least one silane that has
a group bonded to silicon by a carbon atom and that carries a
sulphonate group or a sulphate group of the formula
--(O).sub.d-SO.sub.3M wherein d=0 or 1 and M=hydrogen, or a
monovalent metal cation, or the corresponding quantity of a
polyvalent metal cation, yet not including polycondensates in which
the C.dbd.C double bonds are formed exclusively by methacrylic
esters that are bound, in the form of a methylene acryl ester
group, to the groups bonded to silicon by carbon. The invention
also relates to composites that consist of such silicic acid
(hetero) polycondensates in combination with fillers, and to
polymers produced by organically polymerising the C.dbd.C double
bonds in the polycondensates or composites. Moreover, the invention
relates to different possibilities for producing the claimed
silicic acid (hetero) polycondensates.
Inventors: |
Wolter; Herbert;
(Tauberbischofsheim, DE) ; Seyfried; Mona;
(Wurzburg, DE) ; Nique; Somchith; (Eisingen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Fraunhofer-Gesellschaft zur Forderung der angewandten Forschung
e.v. |
Munchen |
|
DE |
|
|
Assignee: |
Fraunhofer-Gesellschaft zur
Forderung der angewandten Forschung e.V.
Munchen
DE
|
Family ID: |
46148877 |
Appl. No.: |
14/122792 |
Filed: |
May 29, 2012 |
PCT Filed: |
May 29, 2012 |
PCT NO: |
PCT/EP2012/060031 |
371 Date: |
November 27, 2013 |
Current U.S.
Class: |
528/30 ;
528/32 |
Current CPC
Class: |
A61K 6/30 20200101; A61K
6/30 20200101; C08G 77/20 20130101; C08G 77/18 20130101; C08G 77/28
20130101; A61K 6/30 20200101; C09J 183/08 20130101; C08F 30/08
20130101; C09J 4/00 20130101; C07F 7/1804 20130101; C08L 33/10
20130101; C08G 77/392 20130101; C08L 33/10 20130101 |
Class at
Publication: |
528/30 ;
528/32 |
International
Class: |
C08G 77/28 20060101
C08G077/28; C08G 77/18 20060101 C08G077/18 |
Foreign Application Data
Date |
Code |
Application Number |
May 27, 2011 |
DE |
10 2011 050 672.1 |
May 27, 2011 |
EP |
11167853.8 |
Claims
1. to 16. (canceled)
17. A silicic acid (hetero) polycondensate of: at least one silane
with a first residue bonded by a carbon atom to silicon and
carrying an organically polymerizable C.dbd.C double bond; at least
one silane with a second residue bonded by a carbon atom to silicon
and carrying a sulfonate group or sulfate group of the formula
--(O).sub.d--SO.sub.3M with d=0 or 1 and with M=hydrogen or a
monovalent metal cation or the corresponding portion of a
multi-valent metal cation; with the proviso that polycondensates in
which the C.dbd.C double bonds are formed exclusively by
methacrylic esters attached in the form of a methylene acrylic
ester group to the groups that are bonded by a carbon to silicon
are excluded.
18. The silicic acid (hetero) polycondensate according to claim 17,
wherein the organically polymerizable C.dbd.C double bond is a
vinyl group or is a part of an allyl group, an acryl group, a
methacryl group, an optionally substituted bicyclo[2.2.1] heptene
group, an optionally substituted bicyclo[2.2.2]octene group, or an
optionally substituted oxabicyclo[2.2.1]heptene group.
19. The silicic acid (hetero) polycondensate according to claim 17,
further comprising third residues bonded by a carbon atom to
silicon and each carrying at least one carboxylic acid group or an
ester derived from the least one carboxylic acid group or a
corresponding salt of the least one carboxylic acid group or a
hydroxyl group, wherein said third residues can be identical with
the first and second residues as defined in claim 1 or can be
different.
20. The silicic acid (hetero) polycondensate according to claim 19,
wherein the third residues, carrying at least one carboxylic acid
group or a hydroxyl group, carry additionally either an organically
polymerizable C.dbd.C double bond or a sulfonate group or a sulfate
group, but not a combination thereof.
21. The silicic acid (hetero) polycondensate according claim 20,
wherein the third residues bonded by a carbon atom to silicon are
at least partially an alkylene group, an arylene group or an
alkylaryl group, wherein the alkylene group, the arylene group, and
the alkylaryl group each can be interrupted optionally by one or
several groups selected from --O--, --S--, --NH--, --S(O)--,
C(O)NH--, --NHC(O)--, --C(O)O--, --C(O)S, --NHC(O)NH--, and
--C(O)NHC(O)--.
22. The silicic acid (hetero) polycondensate according to claim 17,
wherein the first and second residues bonded by a carbon atom to
silicon are at least partially an alkylene group, an arylene group
or an alkylaryl group, wherein the alkylene group, the arylene
group, and the alkylaryl group each can be interrupted optionally
by one or several groups selected from --O--, --S--, --NH--,
S(O)--, --C(O)NH--, --NHC(O)--, --C(O)O--, --C(O)S, --NHC(O)NH--,
and C(O)NHC(O)--.
23. The silicic acid (hetero) polycondensate according to claim 17,
further comprising a silane with a fourth residue bonded by a
carbon atom to silicon and carrying an organically polymerizable
C.dbd.C double bond and further carrying a sulfonate group or a
sulfate group.
24. The silicic acid (hetero) polycondensate according to claim 23,
wherein the first and second residues bonded by a carbon atom to
silicon are at least partially an alkylene group, an arylene group
or an alkylaryl group, wherein the alkylene group, the arylene
group, and the alkylaryl group each can be interrupted optionally
by one or several groups selected from --O--, --S--, --NH--,
--S(O)--, --C(O)NH--, --NHC(O)--, --C(O)O--, --C(O)S, --NHC(O)NH--,
and --C(O)NHC(O)--.
25. The silicic acid (hetero) polycondensate according to claim 17,
made by using additionally at least one hydrolytically condensable
metal compound of a metal, selected from metals of the main groups
Ill and IV and metals of the transition metal groups III to VI.
26. The silicic acid (hetero) polycondensate according to claim 17,
wherein the silicic acid (hetero) polycondensate is
water-soluble.
27. The silicic acid (hetero) polycondensate according to claim 17
as a dental material or dental adhesive.
28. A composite, comprising a silicic acid (hetero) polycondensate
according to claim 17 and a filler incorporated into the silicic
acid (hetero) polycondensate.
29. The composite according to claim 28 as a dental material or
dental adhesive.
30. A polymerisate obtained from a silicic acid (hetero)
polycondensate of claim 17 by polymerization of at least some
(meth)acryl groups contained in said silicic acid (hetero)
polycondensate.
31. The polymerisate according to claim 30 as a dental material or
dental adhesive.
32. A method for preparing a silicic acid (hetero) polycondensate
according to claim 17, comprising the steps of: providing at least
one silane with a first residue that is bonded by a carbon atom to
silicon and that carries an organically polymerizable C.dbd.C
double bond, wherein the at least one silane with the first residue
is hydrolytically condensable, with the proviso that no silanes in
which the C.dbd.C double bonds are formed exclusively by
methacrylic esters which are attached in the form of a methylene
acrylic ester group to the groups that are bonded by a carbon to
silicon, are provided; providing at least one silane with a second
residue that is bonded by a carbon atom to silicon and that carries
a sulfonate group or sulfate group of the formula
--(O).sub.d--SO.sub.3M with d=0 or 1 and with M=hydrogen or a
monovalent metal cation or a corresponding portion of a
multi-valent metal cation, wherein the at least one silane with the
second residue is hydrolytically condensable; and co-condensing the
at least one silane with the first residue and the at least one
silane with the second residue under hydrolytic conditions.
33. The method according to claim 32, carrying out the step of
co-condensing by a sol gel process.
34. A method for preparing a silicic acid (hetero) polycondensate
according to claim 17, comprising the steps of: generating or
providing a silicic acid polycondensate of at least one silane with
a first residue bonded by a carbon atom to silicon and carrying an
organically polymerizable C.dbd.C double bond, with the proviso
that no silanes in which the C.dbd.C double bonds are formed
exclusively by methylene acrylic esters are generated or provided;
and reacting only a portion of the at least one silane with said
first residue with a compound which carries a sulf(on)ate group and
can attack at the organically polymerizable C.dbd.C double bond so
that some of the groups containing the organically polymerizable
C.dbd.C double bond are reacted to a sulf(on)ate-containing
group.
35. The method according to claim 34, wherein the organically
polymerizable C.dbd.C double bond is a vinyl group or is a part of
an allyl group, an acryl group, a methacryl group, an optionally
substituted bicyclo[2.2.1] heptene group, an optionally substituted
bicyclo[2.2.2]octene group, or an optionally substituted
oxabicyclo[2.2.1]heptene group, and wherein the compound which
carries a sulf(on)ate group and can attack the C.dbd.C double bond
is a thioalkane sulfonate or an aminoalkane sulfonate.
36. A method for preparing a silicic acid (hetero) polycondensate
according to claim 17, comprising the steps of: generating or
providing a silicic acid polycondensate from at least two different
silanes, including a silane with a first residue bonded by a carbon
atom to silicon and carrying at least one organically polymerizable
C.dbd.C double bond, with the proviso that no silanes in which the
C.dbd.C double bonds are formed exclusively by methylene acrylic
esters are generated or provided, and further including a silane
with a reactive residue bonded by a carbon atom to silicon and
carrying a reactive group; and reacting said reactive group of said
silane with said reactive residue with a compound, said compound
containing a sulf(on)ate group and further containing a residue
which can attack said reactive group and form a link, so that the
sulf(on)ate group is introduced into said reactive residue.
37. The method according to claim 36, wherein said reactive group
is a strained hetero ring.
38. The method according to claim 37, wherein the strained hetero
ring is an epoxy group.
39. The method according to claim 37, wherein said compound is
sodium sulfate, sodium sulfite, a primary aminoalkane sulf(on)ate,
or a secondary aminoalkane sulf(on)ate.
40. The method according to claim 36, wherein said compound is
sodium sulfate, sodium sulfite, a primary aminoalkane sulf(on)ate,
or a secondary aminoalkane sulf(on)ate.
Description
[0001] Silicic acid (hetero) polycondensates comprising organically
polymerisable groups and either sulphonate groups or sulphate
groups, organic polymerisates produced therefrom, and a method for
producing said polycondensates
[0002] The present invention concerns silicic acid (hetero)
polycondensates, comprising first groups, bonded by carbon to
silicon and comprising at least one polymerizable C.dbd.C double
bond, as well as second groups, also bonded by carbon to silicon
and comprising either sulfonate or sulfate groups, as well as
polymers which can be obtained by the polymerization of the afore
mentioned double bonds.
[0003] Polymerizable organic compounds with acid groups are
important components for medical products for achieving desired
material properties like wetting, etching effect, complexing, and
thereby adhesion on biological interfaces. Dental adhesives are
based on such conventional monomeric compounds, but exhibit still
some considerable deficits. An essential problem in this context is
that the etching effect is often insufficient within the context of
self-etch application for realizing the necessary retentive
structures required for the adhesion and thus a long-lasting
connection between dental tissue and restoration material.
Therefore, a prior separate etching step with an etching gel cannot
be avoided; this, in turn, increases the susceptibility for errors
and the treatment costs. Concerning the increasing demands in
regard to biocompatibility (reference is being had to the allergy
discussion in connection with dental monomers), the above systems
also offer no solution. Since the components of the adhesive in
case of a restoration come closest to the tooth roots as well as
blood vessels, it is of special interest from a toxicological
viewpoint to provide systems that are free of monomers.
[0004] In the patent application DE 44 16 857 C1, carboxylic
acid-functionalized (meth)acrylate alkoxysilanes are described.
They are characterized by a plurality of possibilities for varying
or adjusting the properties of the inorganic-organic composite
polymers produced therefrom. As a result of the contained
carboxylic acid groups, additional reaction possibilities (e.g.,
glass ionomer reactions) as well as an improved adhesion on
inorganic surfaces arise. The etching effect (see self-etch
application) of a carboxylic acid group is however nowhere as
strong as that of an S--OH functionality. The same holds true for
the phosphonic acid-based systems disclosed in EP 1 377 628 B1.
Therefore, up to now, it is not possible to obtain with hybrid
polymer-based systems a stable enough connection between dental
tissue and restoration material in the context of the desirable
self-etch application.
[0005] For several application purposes, like the stabilization of
aqueous silicates or the production of electro-viscous liquids,
emulsifiers, detergents or foaming agents, monomeric or condensed
silanes containing sulfonate or sulfate groups have been developed.
Thus, U.S. Pat. No. 6,777,521 discloses silicone sulfate polymers
which are obtainable by the reaction of suitable epoxy compounds
with metal sulfate. U.S. Pat. No. 3,328,449 discloses
sulfopropylated organo-functional silanes and siloxanes which can
be obtained by means of reacting sultones. Organo siloxane
sulfosuccinates in which a sulfonated succinic acid ester is bonded
by the oxygen atom of the ester group by an alkylene group to a
silicon atom are disclosed in U.S. Pat. No. 4,777,277. The
preparation of a hydrolytically condensable bis-sulfosuccinate
amide of a diaminosilane, obtained by the reaction of the free
carboxylic acid of the suitable succinate amide with sodium
sulfite, is disclosed in example 1 of U.S. Pat. No. 4,503,242. A
silane which carries a sulfonate group and a hydroxyl group at an
alkylene oxyalkylene group of the silicon is disclosed in U.S. Pat.
No. 5,427,706.
[0006] The use of purely organic monomers which carry a terminal
sulfonate group as well as an unsaturated olefinic group for
concurrent etching and base-coating ("priming") of teeth is
suggested in US 2002/0119426 A1. Also, U.S. Pat. No. 6,759,449 B2
discloses dental adhesive compositions which carry an organically
polymerizable (meth)acrylic acid group as well as an acidic group.
In this context, no distinction is made between sulfonate groups
and phosphonate groups or other acidic groups concerning the
usability of the compounds and their properties. The same holds
true for US 2003/0055124 A1; only for the (meth)acrylamido
phosphonic acids, but not for the also disclosed corresponding
sulfonic acids, information is provided for the preparation.
Another application, US 2008/0194730, essentially by the same group
of inventors, suggests again for dental composites the use of
self-etch polymerizable N-substituted (meth)acrylic acid amide
monomers which carry additionally an acidic unit, selected from
phosphonic acid units and sulfonic acid units. N-methacryloyl
aminoalkyl sulfonic acids can be used according to the disclosure
of EP 1 421 927 A1 as self-etch primers for dental purposes.
[0007] DE 102 06 451 A1 discloses dental adhesive compositions from
acidically polymerizable nanoparts in an aqueous phase. The
nanoparticles consist of siloxanes having acidic as well as
organically polymerizable groups bonded thereto. The acidic groups
can be either phosphonate groups or sulfonate groups; individual
specific advantages for one or the other group are not specified.
The only example of use discloses a specific adhesion value of a
dental adhesive from a phosphonic acid-containing material on a
tooth surface. A process for producing sulfonate group-containing
silanes or siloxane is neither mentioned generally nor in regard to
the disclosed compounds.
[0008] There is a need for organically polymerizable silicic acid
(hetero) polycondensates of superior properties for the application
in particular in the dental field. Here, an improved adhesion
and/or an improved etching function and/or an adaptation of the
optical properties for the cosmetic appearance are especially
relevant. To provide a remedy in this context is the object of the
present invention.
[0009] For solving this object, silicic acid (hetero)
polycondensates are provided which have organically polymerizable
groups, in particular (meth)acryl groups, as well as sulfate groups
or sulfonate groups. In this context, it has been surprisingly
found that in all prepared materials the sulfonate group or sulfate
group has a substantially stronger etching effect than a
phosphonate group in a comparable position.
[0010] The silicic acid (hetero) polycondensates according to the
invention encompass first groups, bonded by carbon to silicon and
having at least one polymerizable C.dbd.C double bond, as well as
second groups that are also bonded by carbon to silicon and have
either sulfonate groups or sulfate groups. These are, at least
formally, co-condensates from at least one silane with a residue,
bonded by a carbon atom and carrying an organically polymerizable
C.dbd.C double bond, in particular a (meth)acryl residue, and at
least one silane with a residue bonded by a carbon atom and
carrying a sulfonate group or sulfate group, in particular of the
formula --(O).sub.d--SO.sub.3M with d=0 or 1 and with M=hydrogen or
a monovalent metal cation or the corresponding portion of a
multi-valent metal cation. Excluded from the claimed subject matter
are such co-condensate in which the C.dbd.C double bonds are
realized exclusively by (meth)acrylic esters which are bonded in
the form of a methylene acrylic ester group to the groups that are
bonded by carbon to silicon because, firstly, the ester group of
the respective methacrylic esters is not stable with respect to
hydrolysis so that in an undesirable manner free alcohol molecules
can be generated, while at the same time the number of methacrylic
acid groups possibly may increase uncontrollably, and, secondly,
the double bond is less accessible on account of steric conditions
because it is not in the outer region of the silyl unit to which it
is bonded so that it cannot be reached as well by its reaction
partners. Moreover, an aspect of the invention concerns a very easy
incorporation of the optionally present (meth)acryl groups, which
can be realized in that they are reacted in the form of the free
acid or activated acid, i.e., are bonded to the condensates or
their silane precursors. This has the result that the (meth)acryl
groups are present in the structures incorporated as (meth)acrylic
esters, (meth)acrylic amides or (meth)acrylic thioesters.
[0011] The expression "co-condensate" is meant to encompass
according to the invention all those condensates which would
generate at least two different silanes upon hydrolysis of the
Si--O--Si bonds. Supra, they were referred to "formally" as
co-condensates because they can be also produced by hydrolytically
condensing a single silane and modifying afterwards only some of
the groups that are bonded by carbon to the silicon atoms; this
will be explained in detail infra.
[0012] The organically polymerizable C.dbd.C double bond to be
employed according to the invention is in several embodiments an
activated double bond. As "activated C.dbd.C double bonds", groups
are to be understood whose double bonds have in their neighborhood
an electron-withdrawing group so that an attack is possible by a
NHR group (a nucleophilic attack). Particularly preferred examples
of such residues are acrylates and methacrylates which, in
accordance with the preceding explanations, are in the form of
(meth)acryl silyl esters, (meth)acryl silyl amides or (meth)acryl
silyl thioesters, i.e., in a form in which the acryl group is
esterified/amidated/thioesterified with the organosilyl group.
[0013] Instead of the expression "activated C.dbd.C double bonds",
the expression "active C.dbd.C double bonds" is also used herein in
some places.
[0014] As an example of organically polymerizable double bonds that
are not active or not activated, the vinyl group, the allyl group
as well as double bonds within a ring, such as those in a
norbornene group, are to be mentioned here. These groups are
sterically also in an external region of the respective silanes so
that they are easily polymerized.
[0015] The expression "'organically polymerizable" is to be
understood as the possibility of polyaddition of the double bonds,
on the one hand, but also the polymerization by the addition of
residues capable of addition, like thio groups or amino groups, on
the other hand. Thus, for example, a norbornene group can be
subjected to a thiol-ene addition.
[0016] The word or the word part **(meth)acrylic . . . " is meant
to encompass the respective methacryl and acryl compounds alike.
The (meth)acryl residues can be in particular a component of a
(meth)acrylic acid ester, thioester or amide. (Meth)acrylic acid
amide residues are preferred compared with the other (meth)acryl
residues because of their better resistance to hydrolysis.
[0017] The expression "sulf(on)ate" encompasses the sulfonate group
and the sulfate group. The expressions "sulfonate group" and
"sulfate group" encompasses the respective acids and salts.
[0018] The polycondensates of the invention can be present in many
different embodiments and can be producible according to different
variants. All variants have in common that they are generated as a
rule by the known sol gel process. In this way, silicic acid
polycondensates are produced which are often referred to also as
ORMOCER.RTM.e. The condensation reaction can occur in the presence
of additional silanes of the formula SiR*.sub.aR**.sub.4-a which
are known in the art in very large numbers. R* means a hydrolyzable
group which enables the incorporation by condensation of the silane
into the network, while R** can be any non-condenseable residue. R*
can be herein OH or a C.sub.1-C.sub.10 alkoxy group, more preferred
a C.sub.1-C.sub.4 alkoxy group, and particularly preferred methoxy
or ethoxy. However, R* can be, as needed, also a halide like Cl,
hydrogen, acyloxy with preferably 2 to 5 carbon atoms,
alkylcarbonyl with preferably 2 to 6 carbon atoms, or
alkoxycarbonyl with preferably 2 to 6 carbon atoms. In some cases,
R* can also be NR.sup.2 with R.sup.2 being hydrogen, alkyl with
preferably 1-4 carbon atoms, or aryl with preferably 6-12 carbon
atoms.
[0019] In this context, the silanes of both variants are selected
in a suitable manner such that the desired condensation level is
achievable with them. Thus, up to three residues, optionally only
two residues, of the silyl group are selected from hydroxyl groups
or--preferred--hydrolyzable groups. Such groups are called
generally network formers. Preferably, they are alkoxy groups,
aryloxy groups or aralkoxy groups, in particular C.sub.1-C.sub.10
alkoxy groups, more preferred C.sub.1-C.sub.4alkoxy groups, and
particularly preferred methoxy or ethoxy. However, as needed in
special cases, it is possible to select be as hydrolytically
condenseable groups in place thereof or partially, in each case
independent of each other, halides like Cl, hydrogen, acyloxy with
preferably 2 to 5 carbon atoms, alkylcarbonyl with preferably 2 to
6 carbon atoms, or alkoxycarbonyl with preferably 2 to 6 carbon
atoms, provided they do not interfere with the reactions which are
needed for producing the condensates according to the invention. In
individual cases, groups of the meaning NR.sup.2 with R.sup.2 being
hydrogen, alkyl with preferably 1-4 carbon atoms, or aryl with
preferably 6-12 carbon atoms can be used instead.
[0020] In addition, the silanes can also contain groups which are
called network modifiers. These are groups which themselves have no
influence on the formation of the condensate but can modify its
properties. They are preferably alkyl groups, aryl groups,
arylalkyl groups, alkylaryl groups or alkylarylalkyl groups that
are substituted or unsubstituted, straight-chain, branched or
provided with at least one cyclic structure; nevertheless, in
individual cases, also corresponding alkenyl groups, arylalkenyl
groups or alkenylaryl groups can be present. Preferred are alkyl
groups, aryl groups or aralkyl groups, in particular
C.sub.1-C.sub.10 alkyl groups, more preferred C.sub.1-C.sub.4 alkyl
groups, and particularly preferred methyl or ethyl.
[0021] In exceptional cases, a single silane can have two groups
that are bonded by carbon to the silicon which either both have at
least one polymerizable C.dbd.C double bond or both have a
sulfonate group or sulfate group.
[0022] When three hydrolyzable groups/hydroxyl groups are present,
a three-dimensional network is generated while silanes with two
hydroxyl groups/two hydrolyzable groups from chains and/or rings.
Because most of the silanes suitable for the invention have only
one group that is bonded by carbon to silicon and that carries
either a polymerizable C.dbd.C double bond or a sulfonate group or
sulfate group, they have, in case of the presence of only two
hydrolyzable groups/OH groups, generally one of the afore mentioned
groups which are referred to as network modifiers
[0023] It can be desirable to provide additional metal compounds
for the incorporation by condensation into the inorganic network.
For this purpose, in particular hydrolytically condensable
compounds of metals of the main groups III and IV as well as of the
transition metal groups III to VI are suitable, e.g., of boron,
aluminum, titanium germanium, zirconium or tin. These metal
compounds are known in large numbers. In these cases, a silicic
acid (hetero) polycondensate is generated in which the afore
mentioned metal atoms are integrated into the Si--O--Si network.
The additional metal compounds are often alkoxy compounds; in
specific embodiments of the invention, the other metal compounds
themselves can also have reactive groups however. In this context,
of special interest for the present invention are complexes which
themselves carry (meth)acryl groups because the latter can be
integrated by a subsequent organic polymerization into the organic
network.
[0024] The preparation of the polycondensates can be divided in
principle into two groups: According to variant (A), different
silanes are provided or generated wherein at least one of them has
a sulfonate group or a sulfate group and at least a second one has
an organically polymerizable group that has at least one C.dbd.C
double bond. In contrast to this, according to variant (B), a
polycondensate of one or several silanes is generated first which
does not yet have all groups necessary for the invention, and then
a modification is carried out at the stage of the polycondensate
which produces the polycondensate according to the invention.
[0025] The variant (A) can be carried out with the aid of a
plurality of starting silanes that are partly commercially
available, partly can be prepared easily by a person of skill in
the art. For example, a methacryl silyl ester can be obtained
easily by reaction of a suitable silyl alcohol with methacrylic
acid chloride or of a suitable silyl epoxide with methacrylic acid.
Other starting silanes are described, for example, in DE 40 11 044
C1 and DE 44 16 857 C1. It is advantageous that also such silanes
can be used which have more than one group containing a C.dbd.C
double bond and/or more than one sulf(on)ate group which are
preferably located at the same residue that is bonded by carbon to
the silicon. One example for this is following (reaction 7):
Reaction 7:
##STR00001##
[0027] The N-methacryl-modified methacrylsilylamide residue used
herein can be produced in that a silane with a hydrocarbon group
that is bonded by a carbon atom to the Si atom is provided and that
carries a primary amino group and a secondary amino group and is
reacted with activated methacrylic acid (e.g., methacryloyl
chloride or anhydride). Variants can be produced in that instead of
the primary amine a hydroxyl group or a thiol group is present
and/or in that instead of the secondary amine a side group with a
primary amine, a hydroxyl group or a thiol group is present.
Examples of suitable aminosilanes are the compounds (aminoethyl
aminomethyl) phenylethyl trimethoxysilane,
N-(2-aminoethyl)-3-aminopropyl-methyldimethoxysilane,
N-(2-aminoethyl-3-aminopropyl) trimethoxysilane,
N-2-aminoethyl-3-aminopropyl tris(2-ethylhexoxy)silane,
6-(aminohexylaminopropyl) trimethoxysilane,
N-(N'-(2-aminoethyl)aminoethyl)-3-aminopropyl trimethoxysilane,
N-(N'-(2-aminoethyl)aminoethyl)-3-aminopropyl
methyldimethoxysilane, N-(N'-(2-aminoethyl)
aminoethyl)-3-aminopropyl triethoxysilane,
N-(N'-(2-aminoethyl)aminoethyl)-3-aminopropyl methyldiethoxysilane,
N-(N'-(2-aminoethyl)aminoethyl)-3-aminopropyl trimethylsilane,
N-(N'-(2-aminoethyl)aminoethyl)-3-aminopropyl
tris(methoxyethoxyethoxy)silane. Analogous compounds with
corresponding hydroxyl groups or thiol groups are disclosed in EP 0
779 890 A1 , for example. The hydrocarbon group can also have
another configuration than in the examples presented above.
[0028] It is evident that, instead of a silyl group with two
functional groups which can be reacted with (meth)acrylic acid,
also one with three or even more such functional groups can be
used. The (meth)acrylsilanes which are obtainable, respectively,
enable due to their respective available number of (meth)acryl
groups an adjustability of the density of the organic network
obtainable by the future polymerization. Of course, the number and
the chemical structure of the residues RO in reaction 7 can be
selected as defined above; the definition "R=Me/Et" in which Me
means methyl and Et means Ethyl, are purely exemplary.
[0029] The silylsulfonate can be prepared, for example, by reaction
of allylsulfonate with a hydridosilane or by reaction of sodium
sulfite with an epoxysilane. The sulf(on)ate silane can also be
modified arbitrarily. For example, the sulfonic acid group of the
corresponding silane can be connected with the silicon atom by
means of a carbon chain that is interrupted by oxygen atoms and/or
amino groups. Such silanes can be obtained by reaction of an
epoxy-containing silane with sodium sulfite, aminoethane sulfonate,
methylaminoethane sulfonate or the like, as is evident for example
from the reaction 6 discussed infra in which these reactions are
carried out, however, only after the hydrolytic condensation of the
respective silanes. When sodium sulfate is used instead of sodium
sulfite, as for example disclosed in U.S. Pat. No. 6,777,521, a
corresponding sulfate is obtained.
[0030] According to variant (B), a condensate is prepared either
from only one silane which carries however not all
invention-relevant groups, wherein afterwards only some of the
groups that are bonded by carbon to the silicon are modified with a
suitable reaction partner (variant B1), mostly by introduction of a
sulfonic acid group or sulfonate group, or two or even more silanes
are used for the preparation of the condensate wherein at least one
of the silanes is modified afterwards (variant B2), also mostly by
introduction of a sulfonic acid group or sulfonate group.
[0031] The variant (B1) has the advantage that it is possible to
adjust arbitrarily the ratio of the groups with polymerizable
double bonds relative to the groups with sulf(on)ate by varying the
amount of added sulfonic acid compound. An example of this variant
is shown in the following reaction 5:
Reaction 5:
##STR00002##
[0033] In the preparation of condensates according to variant (B),
already known compounds can also be employed, of course, or known
reaction sequences can be used because known (meth)acrylsilanes as
well as known sulfonate group-containing silanes can be used. The
preparation of condensates as shown in stage 1 of reaction 5 is
already known from DE 44 16 857. Afterwards, some of the
methacrylate residues are used for attaching a sulfonate group; in
the example, a thioalkane sulfonic acid is used for this purpose.
In this concrete example, it is important of course that the
thioalkane sulfonic acid is used in less than stoichiometric
amounts in order to preserve some (meth)acrylate groups. The
advantage of a reaction as in this example resides in that the
ratio of (meth)acrylate groups to sulfonic acid groups or sulfate
groups in the condensate can be selected arbitrarily. Another
advantage resides in that the hydroxyl group can be preserved that
resulted from the ring opening of the epoxide because it must not
be used for the attachment of the (meth)acrylate. Hence, it can be
used for other purposes, e.g., for increasing the matrix
hydrophilicity of the silicic acid polycondensates or for the
attachment of other reactive groups, for example, of a further
(meth)acrylate group.
[0034] Of course, this reaction can be modified in any manner by an
easy exchange of substituents for other substituents, as is known
from the art. Accordingly, an aminosilane can be used instead of an
epoxysilane, for example, so that the methacryl group is present in
the form of the methacrylamide. As described above in relation to
variant (A), the silane used as a starting material can contain of
course also several reactive groups which can react with activated
(meth)acrylic acid, or a silane is used from the start which
carries a (non-activated) double bond, for example, a vinyl silane
or allyl silane. Another variant is the exchange of the methacrylic
acid by a bridged ring system such as a norbornene group which can
be obtained by conversion of cyclopentadiene; see the following
reaction:
##STR00003##
[0035] With regard to employable norbornene silane and related
compounds, reference is being had to DE 196 27 198 A1. Thus, the
norbornene ring shown at the top in the reaction scheme can be
optionally substituted, of course; also a bicyclo[2.2.2]octene
residue can be present instead of the norbornene residue (i.e., of
bicyclo[2.2.1]heptane residue). Furthermore, the double
bond-containing five-membered ring of the condensed system can
contain an oxygen atom when the (meth)acryl group is reacted with
furan instead of cyclopentadiene.
[0036] The variant (B2) can be explained by means of the following
scheme:
##STR00004##
[0037] This reaction scheme shows the co-condensation of two
silanes wherein one of them carries a (meth)acryl group, the other
a strained hetero ring. The hydrolytic condensation can be carried
out in a known manner in such a way that the hetero ring remains
closed. A sulfonate group is attached after the condensation
reaction to the hetero ring. When this is done according to b) by
means of the attachment by means of an amino group, the reaction
can be carried out easily--and also in known manner--in such a way
that the amino group does not attack or does hardly attack the
double bond of the methacryl group.
[0038] According to the reaction scheme a condensate according to
the invention is produced as describe above. With a reaction
carried out in this way, the ratio of (meth)acryl groups to
sulf(on)ate groups can be determined by the ratio of the employed
silanes relative to each other. Incidentally, the same or
comparable reaction types as described supra can be also used.
[0039] Instead of a methacryl group as shown herein, other C.dbd.C
double bond-containing groups which are bonded in any manner to the
respective silicon atom can be used of course. A small selection is
shown in the following scheme:
Reaction 6:
##STR00005##
[0041] The use of a silane which was obtained as shown in reaction
5, step 1, by reaction of an epolysilane with methacrylic acid is
another alternative. In this alternative, step 2, the hydrolytic
condensation, does not follow immediately after the preparation of
the silane, as shown in reaction 5, but the methacrylated silane is
mixed with additional epoxysilane and the mixture of epoxysilane
with methacrylsilane is subjected to the hydrolytic condensation,
as shown in reaction 6.
[0042] The silicic acid (hetero) polycondensates according to the
invention can carry other functional groups which can impart to
them advantageous properties for special applications. Foremost,
carboxylic acid group and hydroxyl groups are to be named in this
context. Examples of the presence of hydroxyl groups are found in
the preceding reactions 5, 6 and in the scheme concerning the
variant B2. They can be obtained, for example, in that an
additional silane carrying such a group is co-condensed with the
remaining starting silanes. Instead, a silane can be used which
has, in addition to this group, a polymerizable C.dbd.C double bond
and/or a sulf(on)ate group, namely optionally at the same group
that is bonded by carbon to the silicon. Suitable silanes will be
described infra.
[0043] All silicic acid (hetero) polycondensates according to the
invention, independent of whether prepared according to variant (A)
or one of the variants (B), can be produced additionally with use
of at least one silane having a residue that is bonded by carbon to
the silicon and has an organically polymerizable C.dbd.C double
bond as well as a sulf(on)ate group. This silane can be
represented, for example, by the formula (I)
R.sup.1.sub.aR.sup.2.sub.bSiZ.sub.4-a-b (I)
wherein R.sup.1 is a hydrolytically condensable residue; R.sup.2 an
alkyl, aryl, arylalkyl, alkylaryl or alkylarylalkyl that is
substituted or unsubstituted, straight-chain, branched or has at
least one cyclic structure, as an exception it can be instead a
corresponding alkenyl or can encompass an alkenyl whose carbon
chain in all cases optionally can be interrupted by --O--, --S--,
--NH--, --S(O)--, --C(O)NH--, --NHC(O)--, --C(O)O----C(O)S,
--NHC(O)NH-- or C(O)NHC(O) groups which can optionally be oriented
in both possible directions; Z is a residue in which are present at
least one (meth)acryl group and at least either a sulfonate group
or a sulfate group that are bonded directly or indirectly by an
unsubstituted or substituted hydrocarbon group to the silicon atom;
a is 1, 2 or 3; b is 0, 1 or 2; and a+b together are 2 or 3. In
particular, it is preferred that the residues Z furthermore have in
each case at least one hydroxyl group or a carboxylic acid group or
an ester derived therefore or a corresponding salt.
[0044] In several preferred embodiments, the silanes of the formula
(I) can be represented by the following formula (Ia):
##STR00006##
wherein: R.sup.1 is a hydrolytically condensable residue, R.sup.3
is an alkylene that is unsubstituted or substituted with a
functional group, straight-chain, branched or has at least one
cyclic structure, A is a linking group, R.sup.4 is an alkylene that
is optionally interrupted by O, S, NH or NR.sup.8 and/or optionally
functionally substituted, M is hydrogen or a monovalent metal
cation or the corresponding portion of a multi-valent metal cation,
preferably selected from alkali cations and alkaline earth cations,
in particular from Na, K, 1/2 Ca, 1/2 Mg, or ammonium is,
[0045] R.sup.5 and R.sup.6, independently of each other, either
have the meaning of R.sup.1 or are alkyl, aryl, arylalkyl,
alkylaryl or alkylarylalkyl, substituted or unsubstituted,
straight-chain, branched or having at least one cyclic structure,
or can be instead in exceptions also a corresponding alkenyl,
arylalkenyl or alkenylaryl,
R.sup.7 is a hydrocarbon group, as has been defined supra, bonded
by a carbon atom to the silicon atom, R.sup.8 is C.sub.1-C.sub.6
alkyl or (meth)acryl, B is vinyl, 2-allyl or, in case of e>1, an
organic residue with e vinyl groups present in each case bonded to
a group located in the curly brackets, Y is a nitrogen atom,
--O--CH.dbd., --S--CH.dbd. or --NH--CH.dbd., and in each case the
oxygen atom, the sulfur atom or the NH group has a bond to the
neighboring C(O) group, b is=0 or 1, c is=0 or 1, with the proviso
that, for the combination of Y being a nitrogen atom, b=0, c=0, and
d=0, the residue R.sup.3 is ethylene, and with proviso that, for
the combination of Y being a nitrogen atom, b=0, c=1, and d=0, the
residue R.sup.4 is an alkylene that is interrupted by O, S, NH or
NR.sup.8 and optionally functionally substituted, d is=0 or 1, and
e is=1, 2 or 3.
[0046] The linking group A in the formula (la) is preferably
selected from (read from the left to the right in the formula la)
C(O)NH, NHC(O), NR.sup.8C(O), C(O)O, and OC(O), and R.sup.8 is
defined as above. In special cases, the linking group A can have
these groups oriented however in a direction opposite to the
reading direction and can be selected additionally from NHC(O)O,
NR.sup.8C(O)O, NHC(O)NH, C(O)NHC(O), and C(O)S. The residue R.sup.4
is substituted in specific embodiments with at least one hydroxyl
group and/or with a residue R.sup.9COOM, wherein R.sup.9 is a
chemical bond or a C.sub.1-C.sub.6 alkylene residue and M is
hydrogen or a monovalent metal cation or the corresponding portion
of multi-valent metal cation, preferably selected from alkali
cations and alkaline earth cations, in particular from Na, K, 1/2
Ca, 1/2 Mg, or ammonium.
[0047] With few exceptions, the syntheses for the preparation of
the silanes of the formula (I) or (Ia) are controlled such that for
the addition of the sulfonic acid group or sulfate group to the
molecule that already contains a (meth)acryl group a C.dbd.C double
bond is available. As desired, to the latter either sodium sulfite
or a sulfonic acid with a residue that is easily reacted by
addition, such as hydroxyl, thio or aminoalkane sulfonic acid, can
be added. Alternatively, the attachment of the sulfonic acid group
can also be carried out by the reverse principle in that hydroxyl,
thio or aminoalkylsilane is reacted with an alkylene sulfonic acid.
With this process, a chain length extension by the carbon atoms of
the alkylene group is of course inevitable, which is the reason why
the first variant is preferred over the second. Finally, there is
still the possibility to cause ring opening of a strained hetero
ring, in particular of a three-membered ring, with sulfite or a
hydroxyl, thio or aminoalkane sulfonic acid. This variant has the
advantage that the ring opening reaction generates another reactive
group which can be used for the subsequent attachment of the
activated (meth)acrylic acid. The three-member ring can be opened
alternatively also by means of a sulfate; in these cases, a sulfate
group-containing product is obtained.
[0048] All together, three basic variants for the production of the
silanes with the formula (I) are available according to the
invention as follows:
Variant (i):
[0049] a. a silane with a hydrocarbon group bonded by a carbon atom
to the Si atom is provided which carries at least two functional
groups, selected from primary amines, secondary amines, hydroxyl
groups and thiol groups, [0050] b. a first one of the two
functional groups is reacted with optionally activated
(meth)acrylic acid and the second one of the two functional groups
is reacted with an optionally activated second carboxylic acid
having a C.dbd.C double bond and optionally at least one other
functionality, and [0051] c. subsequent to the aforementioned
reaction, a sulfonate group-containing or sulfate group-containing
compound or a sulfite is added to the C.dbd.C double bond of the
carboxylic acid residue reacted with the second functional group in
such a way that at the (meth)acryl residue reacted with the first
one of the two functional groups such an addition does not take
place, which can be ensured in different ways, e.g., by the molar
ratio of the groups reacted with each other, wherein the second
carboxylic acid having a C.dbd.C double bond can be a (meth)acrylic
acid or another double bond-containing carboxylic acid.
Variant (ii):
[0051] [0052] a. a silane with a hydrocarbon group bonded by a
carbon atom to the Si atom is provided which carries at least one
reactive hetero ring, selected from the three-membered rings
oxacycyclopropyl (=epoxy), azacyclopropyl and thiocyclopropyl and
cyclic carbonates (the latter can be obtained by reaction of an
epoxy ring with CO.sub.2, but also by other pathways, as disclosed
in DE 44 23811 in detail), [0053] b. the hetero ring is reacted
with a sulfite or a sulfate or a sulfonate group-containing or a
sulfate group-containing compound, and [0054] c. at least the OH,
SH or NH.sub.2 group that is obtained in this way is reacted with
(meth)acrylic acid that is optionally activated. Variant (iii)
[0055] a. a silane with a hydrocarbon group bonded by a carbon atom
to the Si atom is provided which has an amino group or a mercapto
group, [0056] b. an alkenyl sulfonate or a sulfone is reacted with
the amino group or the mercapto group, and [0057] c. the secondary
amino group or thio group produced in b. is reacted with (meth)
acrylic acid that is optionally activated.
[0058] An example of the preparation of such a silane according to
variant (i) is shown below in an exemplary way by means of the
reaction 1:
##STR00007##
[0059] A reaction according to variant (ii) is shown below in an
exemplary way by means of the reaction 3:
Reactions 3a and 3B:
##STR00008##
[0061] A conversion according to variant (iii) is shown below in an
exemplary way by means of the reaction 4;
Reaction 4.
##STR00009##
[0063] The preceding reaction examples show conversions to
suifonates. By the use of sulfates, as disclosed in U.S. Pat. No.
6,777,521, instead of sulfites in the reactions according to
variant (ii), the corresponding sulfate compounds can be
obtained.
[0064] The syntheses for producing the silicic acid (hetero)
polycondensates according to the invention are characterized in all
variants by the simplicity of the reaction control, a low number of
working steps, and good yields.
[0065] As partially already mentioned above, in specific
embodiments of the invention a hydrocarbon residue bonded to a
silicon atom can be substituted with more than one sulfonic acid
group or sulfuric acid group and/or with more than one (meth)acryl
group. By the presence of more than one (meth)acryl group the
network which forms upon polymerization of the condensates can
become even more fine-meshed. In this connection, is should be
noted that by the contents of polymerizable double bonds the
modulus of elasticity of the future organically polymerized polymer
can be adjusted in such a way that the polymer becomes more or less
flexible and thereby less hard or harder. By the presence of more
than one sulfonic acid group or sulfuric acid group the etching
effect of the condensate is further increased.
[0066] The inventors have surprisingly found that already with low
sulfonic acid contents an enormous etching effect on the dental
tissue can be observed. This can be demonstrated by means of a
comparison of the average roughness of the enamel surface: Polished
enamel has an average roughness of about 0.21 .mu.m, measured with
an optical profilometer of the company UBM. With a phosphonic
acid-functionalized silicic acid polycondensate of
glycerin-l-methacryloyl-2-(siloxypropyl) carboxymethyl phosphonic
acid, roughness in the range of 0.33 can be achieved. With
condensates of the compounds according to the invention, the
roughness is within the range of more than 0.45 .mu.m. Dental
enamel images are shown in the FIGS. 1a and 1b.
[0067] The versatility and the specific adaptation possibility to
the respective purpose of the silicic acid (hetero) polycondensates
according to the invention and the polymers configured or formed
therefrom are based quite substantially on the indicated
preparation possibilities. Hence, the use of additional monomers,
e.g., the use of reactive diluting agents with the goal of a
sufficient organic crosslinking of the polymers, can therefore
often be dispensed with. This is an advantage in particular when
the condensates according to the inventions and the polymers
available therefrom are to be used in the medical field, e.g.
dental field. For it is known from the increasing public discussion
of the subject matter, that (meth)acrylate-based monomers are
suspected of triggering allergies.
[0068] The inventors, moreover, were surprised by the fact that the
silicic acid polycondensates according to the invention are
generally water-soluble, even through they carry a large number of
(meth)acrylate groups and have an inorganically condensed
structure. This has great advantages for many applications, wherein
medical applications are to be mentioned foremost. For the
condensates can be applied in aqueous medium, i.e. can be applied
in any form without the use of a non-aqueous solvent being
required. But also for industrial applications water-based
reactions are always advantageous, namely already for reasons of
occupational safety and the environmental compatibility.
[0069] The possibility of forming other reactive groups in the
silanes besides the sulfonic acid functional group opens up
additional possibilities. Thus, sulfonic acid groups have a
stronger etching effect than carboxyl groups while the latter have
complexing properties. Should there be additional hydroxyl groups,
these can be used either for improving wetting at the base surface
or for further reactions which can further modify the silicic acid
(hetero) polysiloxanes according to the invention. One example is
complexing or reacting with a dicarboxylic acid (which can be
caused, e.g., by means of appropriately activated acid
molecules).
[0070] In addition to degree of polymerization and etching effect,
the groups and residues located according to the invention on the
polycondensates of the invention have further properties which are
favorable for several intended purposes: The sulfonate group or
sulfate group is a charge carrier for which reason uses are
possible as electrophoresis gels, as materials for the
electrophoretic coating or as materials that modify conductivity or
antistatic properties. Moreover, the group can serve as an acidic
catalyst, namely, on the one hand, for the sol gel process (a later
separation step to the catalyst separation can then be dispensed
with) and, on the other hand, in respect to the future use (an
example are the mesoporous membranes with sulfonic acid groups
which can serve as catalyst for chemical processes). The group
provides furthermore a good solubility in polar media. Particularly
for dental purposes, but not exclusively for this purpose, it
serves as an adhesion promoting group for inorganic, organic as
well as hybrid surfaces. Like carboxylic acid groups, it can also
form ionic bonds by means of which e.g., alkali, earth alkali,
ammonium, Ti, Zr, Sn, Ca and other suitable cations can be
incorporated in the form of their salts into the polycondensate
network. In this way, several modification or material-specific
adjustments, e.g., concerning the X-ray opacity, the refractive
index or the contact toxicity, can be achieved. By the sulfonate
groups or sulfate groups in the material, the material is moreover
imparted with an antimicrobial effect. But the invention can be
applied also in quite different fields because e.g.
proton-conducting membranes, e.g., for fuel cells, can be formed
with sulfonate group-containing or sulfate group-containing
materials. Further, the materials are suitable e.g. as an ion
exchanger, as a pseudo-static phase in the electrokinetic
chromatography or as substances with interfacial tension lowering
action (detergent).
[0071] The use in the medical sector (specifically dental field),
e.g., as an adhesive promoting agent (monomer-free bonding) and as
a matrix component for cements, is in particular favored by the
combination of the sulfonate groups or sulfate groups and
optionally additionally by the --CO.sub.2H groups with
polymerizable/polyadditive double bonds in a molecule.
[0072] The quantitative proportion of C.dbd.C double
bond-containing silane to sulf(on)ate-containing silane in the
condensate according to the invention is basically not critical.
Thus, the number of the C.dbd.C double bond-containing residues
that are bonded by carbon to silicon to the number
sulf(on)ate-containing residues bonded by carbon to silicon can be,
for example, in the range of 10:1 to 1:10. Particularly preferred
is a ratio of 3:1 to 1:1, and often a ratio of about 1:1 will be
selected. Ratios in which the number of the C.dbd.C double
bond-containing residues predominates in comparison to the number
of sulf(on)ate-containing groups are preferred in several cases
because then an especially tight organic network can be generated.
The same goal can be achieved of course also in that those groups
are used that are bonded by carbon atoms to the silicon and that
carry more than one C.dbd.C double bond.
[0073] By use of any fillers (particles, fibers), as the particles
described for example in DE 196 43 781, DE 198 32 965, DE 100 18
405, DE 104 10 38, DE 10 2005 018 351, DE 10 2005 061 965 as well
as in DE 10 2005 053 721, or of SiO.sub.2 particles in combination
with the silicic acid (hetero) polycondensates according to the
invention, the corresponding composites are obtained. SiO.sub.2
particles, for example, can be obtained by known sol gel processes;
they can have a very narrow diameter distribution. These or also
differently composed nanoparticles can be modified on their
surface, e.g., silanized, in order to adapt their surface
properties to those of the matrix.
[0074] The composites can be plastically processed and are
characterized by very high filler concentrations that are possible
(see nanohybride composites) in combination with an excellent
processibility. Therefore, different properties can be adjusted in
wide ranges for the resultant silanes, resin systems, matrix
systems as well as for the filled systems (composites) and adapted
to the requirements.
[0075] Particularly preferred is the use of the invention in the
dental field, i.e., as an adhesive, for example. In this context,
the silicic acid (hetero) polycondensate obtained by hydrolytic
condensation from the silanes according to the invention can be
mixed with one or several additives and/or fillers, in particular
for the production by dental composites, before organic curing. An
essential component in this regard are nanoparticulate fillers or a
combination of such fillers of different size or different
composition, as mentioned above, optionally in combination with
other known fillers like particulate dental glasses, e.g., Ba--Sr
aluminum borosilicates.
[0076] The filler can be added according to the desired field of
application in very different total quantities. Thus, adhesives
need only relatively small filler amounts. Also, fissure sealers,
coatings for the neck of the tooth, and the like contain in general
a proportion of less than 50 wt. %, e.g., 1-50 wt. % and preferably
from approx. 1 to 20 wt. % of a filler. In other cases, the filler
can be present optionally e.g. in a proportion of 50 wt. % of the
composite, or even clearly above that, and in particular in a
proportion of 70 to 90 wt. % of the composite when higher filled or
highly filled composites are needed, e.g., for fillings and the
like.
[0077] In accordance with the intended special purpose of use,
suitable additives can be added to the silicic acid (hetero)
polycondensates or the composite of the invention, such as
initiators, coloring agents (dyes or pigments), oxidation
inhibitors, polymerization inhibitors (for avoiding a premature
polymerization), leveling agents, UV absorber, stabilizers,
microbiocidal active ingredients or the like, as is known to a
person of skill in the art. Examples of polymerization initiators
are initiators for radical polymerization, namely for thermal
curing like peroxides (e.g., benzoyl peroxide) or photo initiators
like benzophenone, camphorquinone or combinations of a-diketones
with amine as a reducing agent, as for example disclosed in DE 199
03 177 C2. For the dual curing of radically and cationically
polymerizable systems, in particular diaryl iodonium or triaryl
sulfonium salts can be added for which the aforementioned
publication also provides examples.
[0078] The filled dental composite (i.e. the organically not yet
crosslinked filled resin), after it has been applied for the
intended purpose, can be crosslinked in suitable manner organically
and thus be cured. Above all, an organic polymerization of the
(meth)acrylate groups is used for this purpose. This is a radical
polymerization that usually occurs with addition of radical
starters like the above mentioned ones and optionally known
activators, with exposure to e.g. visible light (blue light; dental
irradiator), i.e. photochemically, thermally or redox-induced, but
also occurs within the scope of 2-component reactions or
anaerobically. The combination of self curing action with e.g.
photo-induced or thermal curing is also possible.
[0079] However, the use of the silicic acid (hetero)
polycondensates according to the invention applies not only to
composites adapted for dental purposes, but inter alia also to the
use in the form of bulk materials, (dental) cements, adhesives,
potting compounds, coating materials, adhesion promoters, binding
agents for ceramic particles (ceramic shaping processes), producing
or priming of fillers and fibers, use in reaction extruders and the
like for most different purposes (in particular for medical, but
also for (micro)optical and (micro)electronic applications). The
condensates can be converted by means of a large number of
processes into structured surfaces or bodies, for example, by silk
screen printing, inkjet printing, direct laser writing, photo
lithography or two-photon or multi-photon polymerization.
[0080] Below, the invention will be explained with the aid of
examples in more detail.
EXAMPLE 1
Preparation of a Silicic Acid Polycondensate According to Variant
A
[0081] To a solution of 3.4 g (0.01 mol) N,N'
dimethacryloyl-3-(2-aminoethylamino)-propylmethyl dimethoxysilane
in acetone/water (ratio 1:1), 2.5 g (0.01 mol)
3-trimethoxysilylpropyl sulfonic acid were added and stirred at
40.degree. C. until the condensation was complete. Afterwards the
volatile components were removed under vacuum.
EXAMPLE 2
Preparation of a Silicic Acid Polycondensate According to Variant
B1 (Reaction 5)
[0082] Stage 1: 3.93 g (0.015 mol) triphenyl phosphine and 0.316 g
(0.06 wt. %) butylhydroxyl toluene were dissolved in 377.8 g (1.521
mol) diethoxy(3-glycidyloxypropyl) methylsilane. Afterwards, the
solution was heated to 85.degree. C. and 142.05 g (1.65 mol)
methacrylic acid added dropwise during 1.5 h. After 24 h at reflux,
the product was dissolved in ethyl acetate and was adjusted with 1N
hydrochloric acid to pH 1-2. After 3 d, the solution was washed
with 1 N sodium hydroxide solution up to a pH value of 12 and,
afterwards, the volatile components removed under vacuum.
[0083] Stage 2: To a solution of 7.78 g (0.008 mol) product of the
stage 1, 0.68 g NaOH in 40 ml ethanol, 1.33 g (0.008 mol) sodium
2-mercaptoethane sulfonate in 40 ml H.sub.2O was added dropwise at
50.degree. C. After 19 h, ethanol was removed at 40.degree. C.
under vacuum, and the aqueous solution was purified twice with
ethyl acetate. The aqueous phase was treated with a cation
exchanger and, afterwards, the volatile components were removed
under vacuum. The product can be redissolved in water.
[0084] Average roughness R.sub.a=0.45 .mu.m (on enamel)
EXAMPLE 3
Preparation of a silicic acid polycondensate according to variant
B2:
[0085] Stage 1: To a solution of 2.2 g (0.01 mol)
methacryloxypropyl trimethoxysilane in 50 ml ethyl acetate, 2.2 g
(0.01 mol) 3-glycidoxypropyl methyldimethoxysilane were added.
After addition of a well-established catalyst, as for example
ammonium fluoride, the reaction mixture was stirred at 40 .degree.
C. until the condensation was complete. After usual work-up, e.g.,
extraction with water, the volatile components were removed under
vacuum.
[0086] Stage 2: The co-condensate of stage 1 was dissolved in 20 ml
ethanol and was heated to 80.degree. C. A solution of (0.01 mol)
sodium bisulfite in 20 ml water was added dropwise and the reaction
mixture was stirred under reflux for 4 h. After evaporation of
ethanol, the aqueous phase was purified with ethyl acetate, treated
with a cation exchanger, and afterwards the volatile components
were removed under vacuum.
EXAMPLE 4
Preparation of a Silane with a Group that is Gonded by Carbon to
the Silicon and Carries a C.dbd.C Double Bond and a Sulfonate
Group
[0087] Stage 1: 5.11 g (0.024 mol) N-(2-aminoethyl)-3-aminopropyl
methyldimethoxysilane was dissolved in 5.21 g triethylamine and 30
ml toluene and was cooled to 0.degree. C. Afterwards, 5.0 ml (0.051
mol) methacrylic acid chloride in 30 ml toluene were added
dropwise. The reaction mixture was stirred for 3 h at room
temperature. The mixture was centrifuged, and the obtained solution
adjusted with 1N hydrochloric acid to pH 1-2. After 24 h, the
volatile components were removed under vacuum.
[0088] Stage 2: 3.92 g (0.013 mol) of the product of stage 1 were
dissolved in 30 ml ethanol, the solution adjusted with sodium
hydroxide to pH 10, and heated to 60.degree. C. Afterwards, 1.93 g
(0.015 mol) sodium 2-mercaptoethane sulfonate dissolved in 40 ml
H.sub.2O were added dropwise, followed by stirring for 4 h. Ethanol
was removed under vacuum and the aqueous solution treated with a
cation exchanger. The volatile components were removed under
vacuum. The product is a water-soluble solid.
[0089] Average roughness R.sub.a=0.58 .mu.m (on enamel)
EXAMPLE 5
Preparation of a Silane with a Group Bonded by Carbon to Silicon
and Carrying A C.dbd.C Double Bond and a Sulfonate Group
[0090] Stage 1: 8.69 g (0.042 mol) N-(2-aminoethyl)-3-aminopropyl
methyldimethoxysilane were dissolved in 50 ml ethyl acetate and
heated to 50.degree. C. A solution of 4.23 g (0.043 mol) maleic
acid anhydride in 30 ml ethyl acetate was added dropwise, followed
by stirring for 19 h. The mixture was centrifuged and the residue
was purified twice with ethyl acetate and was dried under
vacuum.
[0091] Stage 2: 6.06 g (0.021 mol) of the product of the stage 1
were dissolved in 5 ml water and 1.72 g NaOH and cooled to
0.degree. C. 2.1 ml (0.021 mol) methacrylic acid chloride were
slowly added dropwise with strong stirring action, followed by
stirring for 5 h at 50.degree. C. Afterwards the volatile
components were removed under vacuum.
[0092] Stage 3: 9.82 g (0.021 mol) of the product of the stage 2
were dissolved in 20 ml water and heated to 60 .degree. .
Afterwards, 2.61 g (0.021 mol) sodium sulfite were added dropwise
under stirring, followed by stirring for 24 h. The aqueous solution
was treated with a cation exchanger and the volatile components
were removed under vacuum. The product can be redissolved in
water.
[0093] Average roughness R.sub.a=0.48 .mu.m (on enamel)
EXAMPLE 6
Preparation of a Silane with a Group Bonded by Carbon to Silicon
and Carrying a C.dbd.C Double Bond and a Sulfonate Group
[0094] Stage 1: 5.04 g (0.040 mol) sodium sulfite were dissolved in
30 ml H.sub.2O and heated to 80.degree. C. A solution of 9.96 g
(0.040 mol) 3-glycidoxypropyl methyldiethoxysilane in 10 ml ethanol
was added dropwise and stirred for 3 h under reflux.
[0095] After evaporation of ethanol the aqueous phase was purified
with ethyl acetate, and the volatile components were removed under
vacuum.
[0096] Stage 2: 5.04 g (0.016 mol) of the product of the stage 1
was dissolved in 10 ml water and 2.79 g (0.070Ehiol) NaOH and
cooled to 0.degree. C. Afterwards, 4.0 ml (0.016 mol) methacrylic
acid chloride were added dropwise, and the reaction mixture was
stirred for 4 h at 30.degree. C. The solution was purified with
ethyl acetate, the aqueous phase treated with a cation exchanger,
and the volatile components removed afterwards under vacuum. The
product is water-soluble.
* * * * *