U.S. patent application number 11/950983 was filed with the patent office on 2008-08-21 for silicone impression material with two-stage curing mechanism.
This patent application is currently assigned to Ernst Muhlbauer GmbH & Co. KG. Invention is credited to Henrik Bottcher, Stephan Neffgen.
Application Number | 20080200584 11/950983 |
Document ID | / |
Family ID | 37909528 |
Filed Date | 2008-08-21 |
United States Patent
Application |
20080200584 |
Kind Code |
A1 |
Bottcher; Henrik ; et
al. |
August 21, 2008 |
Silicone impression material with two-stage curing mechanism
Abstract
A subject-matter of the invention is an impression material with
at least one compound with at least two alkenyl groups as component
(a), at least one compound with at least one chelating group as
component (b), at least one organohydropolysiloxane as component
(c), at least one hydrosilylation catalyst as component (d) and at
least one compound with a chelatable metal atom as component (e),
the chelating group of the component (b) exhibiting no reactive
groups which can react with the component (c) and/or the component
(d). The invention achieves a long storage stability.
Inventors: |
Bottcher; Henrik; (Hamburg,
DE) ; Neffgen; Stephan; (Hamburg, DE) |
Correspondence
Address: |
Casimir Jones, S.C.
440 Science Drive, Suite 203
Madison
WI
53711
US
|
Assignee: |
Ernst Muhlbauer GmbH & Co.
KG
Hamburg
DE
|
Family ID: |
37909528 |
Appl. No.: |
11/950983 |
Filed: |
December 5, 2007 |
Current U.S.
Class: |
523/109 ;
433/214 |
Current CPC
Class: |
A61K 6/90 20200101 |
Class at
Publication: |
523/109 ;
433/214 |
International
Class: |
A61K 6/10 20060101
A61K006/10; A61C 9/00 20060101 A61C009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 16, 2006 |
EP |
06 023 846.6 |
Claims
1. Impression material with a) at least one compound with at least
two alkenyl groups as component (a), b) at least one compound with
at least one chelating group as component (b), c) at least one
organohydropolysiloxane as component (c), d) at least one
hydrosilylation catalyst as component (d) and e) at least one
compound with a chelatable metal atom as component (e), the
chelating group of the component (b) exhibiting no reactive groups
which can react with the component (c) and/or the component
(d).
2. Impression material according to claim 1, characterized in that
the chelating group of the compound of the component (b) is a
dicarbonyl group, in particular a 1,3-dicarbonyl group, such as a
.beta.-dicarboxylate or .beta.-ketoester; use is preferably made of
compounds of the formulae
R.sup.5.sub.aR.sup.1.sub.bSiO--(SiR.sup.1.sub.2O).sub.c--(SiR.sup.1R.sup.-
5O).sub.d--SiR.sup.1.sub.b--R.sup.6.sub.a and
R.sup.5.sub.aR.sup.1.sub.bSiO--[(SiR.sup.1.sub.2O).sub.c--(SiR.sup.1R.sup-
.5O).sub.d--(R.sup.7).sub.g].sub.h--OSiR.sup.1.sub.bR.sup.5.sub.a
with R.sup.1=linear or branched alkyl, fluoroalkyl, cycloalkyl or
aryl; R.sup.2=linear or branched alkylene, fluoroalkylene,
cycloalkylene or arylene; R.sup.3=linear or branched alkylene with
1 to 10 carbon atoms, cycloalkylene or arylene; R.sup.4=linear or
branched alkyl, cycloalkyl, aryl, NR.sup.1.sub.2, NHR.sup.1 or
alkoxy; R.sup.5=R.sup.4--CO--R.sup.3.sub.f--CO--X.sub.e--R.sup.2--,
R.sup.6=R.sup.4--COR.sup.3.sub.f--CO--X.sub.e--R.sup.2;
R.sup.7=SiR.sup.1.sub.2--R.sup.2--X.sub.e--CO--R.sup.3.sub.f--CO--X.sub.e-
--R.sup.2--SiR.sup.1.sub.2; X=O or NR.sup.1; a=0 to 3; b=3-a; c=0
to 10 000; d=0 to 500; e=0 or 1; f=0 or 1; g=1 to 100 and h=1 to
1000.
3. Impression material according to claim 2, characterized in that
R.sup.1 is a methyl group.
4. Impression material according to claim 2 or 3, characterized in
that R.sup.3 is a methylene group.
5. Impression material according to one of the preceding claims,
characterized in that the chelating group of the component (b)
exhibits no reactive groups chosen from the group consisting of
hydroalkyl group, amino group and carboxyl group.
6. Impression material according to one of the preceding claims,
characterized in that the impression material consists of at least
two components B and C, the component B comprising the components
(a), (b) and (c) and the component C comprising the components (d)
and (e).
7. Impression material according to claim 6, characterized in that
the components B and C are stable on storage for more than 3
months, preferably for more than 6 months, more preferably for more
than 12 months and particularly preferably for more than 24
months.
8. Impression material which can be obtained by mixing the
components B and C according to claim 6.
9. Impression material according to claim 7, characterized in that,
during the mixing and/or after the mixing of the components B and
C, the mixture changes, in a first stage, from a relatively thin
starting consistency which can pass through a mixer to a more
viscous plastic phase, before it cures, in a second stage, to give
its final elastic form.
10. Cured impression material, which can be obtained from an
impression material according to one of the preceding claims.
11. Process for the preparation of an impression of an object, an
impression of which is to be taken, characterized in that an
impression material according to one of claims 1 to 9 is used, in
which, in a first step, the components (a)-(e) are mixed, in a
second step, the mixture is brought into contact with a surface of
an object, an impression of which is to be taken, and,
subsequently, the impression is removed.
12. Use of a compound with at least one chelating group which is a
.beta.-dicarboxylate or .beta.-ketoester, preferably of the
formulae
R.sup.5.sub.aR.sup.1.sub.bSiO--(SiR.sup.1.sub.2O).sub.c--(SiR.sup.1R.sup.-
5O).sub.d--SiR.sup.1.sub.b--R.sup.6.sub.a and
R.sup.5.sub.aR.sup.1.sub.bSiO--[(SiR.sup.1.sub.2O).sub.c--(SiR.sup.1R.sup-
.5O).sub.d--(R.sup.7).sub.g].sub.h--OSiR.sup.1.sub.bR.sup.5.sub.a
with R.sup.1=linear or branched alkyl, fluoroalkyl, cycloalkyl or
aryl; R.sup.2=linear or branched alkylene, fluoroalkylene,
cycloalkylene or arylene; R.sup.3=methylene; R.sup.4=linear or
branched alkyl, cycloalkyl, aryl, NR.sup.1.sub.2, NHR.sup.1 or
alkoxy; R.sup.5=R.sup.4--CO--R.sup.3.sub.f--CO--X.sub.e--R.sup.2--;
R.sup.6=R.sup.4--CO--R.sup.3.sub.f--CO--X.sub.e--R.sup.2;
R.sup.7=SiR.sup.1.sub.2--R.sup.2--X.sub.e--CO--R.sup.3.sub.f--CO--X.sub.e-
--R.sup.2--SiR.sup.1.sub.2 X=O or NR.sup.1; a=0 to 3; b=3-a; c=0 to
10 000; d=0 to 500; e=0 or 1; f=1; g=1 to 100 and h=1 to 1000.
13. Use according to claim 12, characterized in that R.sup.1 is a
methyl group.
14. Use according to claim 12 or 13, characterized in that R.sup.3
is a methylene group.
Description
[0001] The invention relates to a multicomponent impression
material which can pass through a mixer with a two-stage curing
mechanism and also to the preparation thereof.
[0002] Multicomponent impression materials which can pass through a
mixer with a two-stage curing mechanism, such as are used, inter
alia, in dentistry, are known to a person skilled in the art, for
example from WO 02/058641 and EP-A-1 502 572.
[0003] The materials which can pass through a mixer and which cure
in two stages make it possible to discharge kneadable materials
from automatic mixing and metering systems.
[0004] WO 02/058641 discloses a multicomponent system for the
taking of impressions which comprises (a) at least one compound
with at least two alkenyl groups, (b) at least one
organohydropolysiloxane, (c) at least one hydrosilylation catalyst,
(d.sub.1) at least one polymeric compound with at least one alkynyl
group and/or (d.sub.2) at least one compound with at least one
Si--OR structural unit, R being H, alkyl, alkoxyalkyl or acyl, and,
in the presence of (d.sub.2), (e) at least one condensation
catalyst and/or condensation crosslinking agent. The compounds (a),
(b), (d.sub.1) and (d.sub.2) are supplied in a component A and the
compounds (c) and (e) are supplied in a component B, which are
mixed with one another, for example by means of a dispenser (e.g.,
MixStar.RTM. or Pentamix.RTM.) In this connection, the mixture
changes from a relatively thin starting consistency which can pass
through a mixer to a more viscous plastic phase, in which the
material is processed, e.g., to give the dental impression, before
it, in a second stage, cures to give its final elastic form. At the
beginning of the mixing, the mixture exhibits a consistency which
can pass through a mixer of >30 mm according to ISO 4823, after
which the mixture changes, by condensation reactions of Si--OR
groups and/or by hydrosilylation reactions of alkynyl groups with
SiH groups, to a second state with a consistency of <30 mm
according to ISO 4823. In this state, which is usually described as
heavy-bodied or putty consistency, the consistency remains
virtually unchanged for a certain period of time. During this time,
the mixture is processed, i.e. the impression is moulded. After
that, the mixture changes, by a hydrosilylation reaction between
alkenyl groups and SiH groups, to a third solid elastic state, in
which the impression result is retained.
[0005] EP-A-1 502 572 discloses a similar multicomponent system
which cures in two stages, in which, in a first step, a
condensation reaction takes place and is followed, in a second
step, by the addition reaction. Siloxanes are used with carbinol,
carboxyl and amine groups in the condensation step.
[0006] It is an object of the invention to produce an impression
material of the type mentioned at the start which is stable, in
particular stable in the long term.
[0007] The invention achieves this object by an impression material
with the characteristics of claim 1. Advantageous embodiments of
the invention are disclosed in the subclaims.
[0008] The invention has recognized that the combinations used for
producing two-stage curing mechanisms described in WO 02/058641 and
EP-A-1 502 572 comprise components carrying reactive groups which
conceal a major disadvantage for the stability of the impression
materials. These are silanol groups in the impression material of
WO 02/058641 and hydroxyalkyl groups, amino groups or carboxyl
groups in the impression material of EP-A-1 502 572. The components
mentioned can react with the hydrosiloxanes which are always
present in the impression materials as crosslinking agent
components, with the splitting off of hydrogen. Thus, for example,
the amino groups and carboxyl groups react in the abovementioned
way in the presence of water, such as is incorporated, for example,
via the filler component as traces of moisture. An additional
disadvantage, recognized by the present invention, of amino groups
and carboxyl groups is that they can interact with the platinum
catalyst preferably used for addition reactions and can cause the
addition crosslinking to be retarded, i.e. to have a delayed
action, or to be completely inhibited. The stability, in particular
the long-term stability, of the impression materials is impaired by
this.
[0009] The invention has recognized that with a compound according
to characteristic (b) of claim 1, which exhibits no reactive
groups, such as hydroxyalkyl groups, secondary amino groups or
carboxyl groups, which can react with an organohydropolysiloxane or
hydrosilylation catalyst, such as platinum, abovementioned
undesirable reactions can be avoided and the stability of the
impression materials can be guaranteed over a long period of
time.
[0010] According to a preferred embodiment of the invention, the
chelating group of the compound of the component (b) is a
dicarbonyl group, in particular a 1,3-dicarbonyl group, such as a
.beta.-dicarboxylate or .beta.-ketoester. Use is preferably made of
compounds of the formulae
R.sup.5.sub.aR.sup.1.sub.bSiO--(SiR.sup.1.sub.2O).sub.c--(SiR.sup.1R.sup-
.5O).sub.d--SiR.sup.1.sub.b--R.sup.6.sub.a
and
R.sup.5.sub.aR.sup.1.sub.bSiO--[(SiR.sup.1.sub.2O).sub.c--(SiR.sup.1R.su-
p.5O).sub.d--(R.sup.7).sub.g].sub.h--OSiR.sup.1.sub.bR.sup.5.sub.a
with R.sup.1=linear or branched alkyl, fluoroalkyl, cycloalkyl or
aryl; R.sup.2=linear or branched alkylene, fluoroalkylene,
cycloalkylene or arylene; R.sup.3=linear or branched alkylene with
1 to 10 carbon atoms, cycloalkylene or arylene; R.sup.4=linear or
branched alkyl, cycloalkyl, aryl, NR.sup.1.sub.2, NHR.sup.1 or
alkoxy;
R.sup.5=R.sup.4--CO--R.sup.3.sub.f--CO--X.sub.e--R.sup.2;
R.sup.6=R.sup.4--CO--R.sup.3.sub.f--CO--X.sub.e--R.sup.2;
[0011]
R.sup.7=SiR.sup.1.sub.2--R.sup.2--X.sub.e--CO--R.sup.3.sub.f--CO--X-
.sub.e--R.sup.2--SiR.sup.1.sub.2;
X=O or NR.sup.1;
[0012] a=0 to 3; b=3-a; c=0 to 10 000; d=0 to 500; e=0 or 1; f=0 or
1; g=1 to 100 and h=1 to 1000.
[0013] Preferably, the impression material consists of at least one
component B (base component) and one component C (catalyst
component), the component B comprising the components (a), (b) and
(c) and the component C comprising the components (d) and (e). The
components B and C are, for example, pastes which are mixed in a
mixing ratio of 10:1 to 1:1, particularly preferably 5:1.
[0014] Preferred alkenyl compounds (a) of the component B are those
with the structure
##STR00001##
with n=0-20 000, R=H--, alkyl-, aryl-, arylalkyl-,
halogen-substituted alkyl and aryl groups, cyanoalkyl-,
cycloalkyl-, cycloalkenyl-, and combinations thereof; R2=alkenyl-,
alkynyl-, halo-, aryl-, alkylaryl-, H--, halogen-substituted alkyl
and aryl groups, in particular alkyl-, and combinations thereof,
R3=R2 or R3 is different from R2, R3 being in particular alkyl-,
methyl-, alkynyl-, ethynyl- or combinations thereof, and
X=polysiloxane, oligosilicic acid esters, polysilicic acid esters,
polyethers, polymeric hydrocarbons, polyesters and copolymers of
the above-mentioned compounds.
[0015] The preferred alkenyl compound (a) can also be a silane
dendrimer with end alkenyl groups or be present as a QM resin with
at least one Si-alkenyl group.
[0016] Preferred organohydropolysiloxanes (c) which are present in
the component B are polyalkyl-, polyaryl- and polyalkylaryl-,
polyhaloalkyl-, polyhaloaryl- or polyhaloalkylarylsiloxanes. They
can be present as oligomers or polymers in linear, branched or
cyclic form or as QM resins and exhibit at least one Si--H bond. QM
resins consist of Q units (SiO.sub.4/2) and M units
(Me.sub.3SiO.sub.1/2).
[0017] Preferred hydrosilylation catalysts (d) which are present in
the component C are the transition metals of subgroup VIII, in
particular platinum, palladium and rhodium or the salts, complexes
and colloids thereof, preferably platinum complexes and salts of
hexachloroplatinic acid, in particular the platinum(0)
1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex.
[0018] Preferred compounds with a chelatable metal atom (e) which
function as condensation catalysts or ligand exchange catalysts and
are present in component C are alkoxymetal complexes R.sub.4Me,
preferably R.sub.4Ti or R.sub.4Zr, and also the oligo- or
polycondensates thereof.
[0019] Preferably, the components (a)-(e) are present in the
impression material in the following constituent amounts:
10-60% by weight of component (a), 1-25% by weight of component
(b), 0.2-10% by weight of component (c), 0.005-5% by weight of
component (d) and 0.1-7% by weight of component (e).
[0020] In addition, the components B and C can comprise additional
constituents, for example inhibitors of the addition reaction,
which slow down the addition reaction or suppress it for a certain
time, water-releasing agents, desiccants, inert carriers,
reinforcing and nonreinforcing fillers, and additional
auxiliaries.
[0021] Inhibitors of the addition reaction are, for example,
disclosed in EP-A-1502572.
[0022] Use is preferably made, as water-releasing agents, of
inorganic fillers, which comprise residual humidity bound at the
surface or water bound in the crystal lattice, zeolites or
specifically humidified fillers or organic materials with a defined
water content.
[0023] Use is preferably made, as desiccants, of dried calcium
sulphate, zeolites, dried fillers or water-absorbing organic
compounds, such as oxazolidines and alkali metal salts of
poly(meth)acrylic acid.
[0024] Use is preferably made, as inert carriers, of mineral oils,
branched hydrocarbons, petrolatum, esters, phthalates, tributyl
acetylcitrate, polyalkylene oxides and polyesters and the
copolymers thereof.
[0025] Use is preferably made, as reinforcing fillers, of highly
dispersed active fillers, such as titanium oxide, aluminium oxide,
zinc oxide, pyrogenic or precipitated silica, fibrous mineral
fillers, such as wollastonite, or fibrous synthetic fillers, such
as glass fibres, ceramic fibres or plastic fibres.
[0026] The nonreinforcing fillers are preferably cristobalite,
quartz, diatomaceous earth, zirconium silicate, calcium silicate,
clay minerals, such as smectites, zeolites, sodium aluminium
silicates, metal oxides, such as aluminium or zinc oxides, and the
mixed oxides thereof, barium sulphate, calcium carbonate, glass
powders, hollow glass spheres and plastic powders.
[0027] The filler can be, according to a preferred embodiment of
the invention, a surface-modified filler, preferably a filler
modified at the surface in organic fashion.
[0028] The filler may, after its surface modification, for example
a silanization, have functional groups on its surface.
[0029] In addition, the dental material according to the invention
may, in order to adjust certain properties, comprise "additives" or
"modifiers" as auxiliaries. Some examples are mentioned below,
without being generally limiting: inorganic and/or organic colour
pigments or dyes, stabilizers (such as, e.g., substituted and
unsubstituted hydroxyaromatic compounds, Tinuvins, terpinenes,
phenothiazine, "HALS" (Hindered Amine Light Stabilizers) and/or
heavy metal scavengers, such as EDTA), plasticizers (such as, e.g.,
polyethylene glycols, polypropylene glycols, unsaturated
polyesters, phthalates, adipates, sebacates, phosphoric acid
esters, phosphonic acid esters and/or citric acid esters),
ion-releasing substances, in particular those which release
fluoride ions (such as, e.g., sodium fluoride, potassium fluoride,
yttrium fluoride, ytterbium fluoride and/or quaternary ammonium
fluorides), bactericides or antibiotically effective substances
(such as, e.g., chlorhexidine, pyridinium salts, penicillins,
tetracyclines, chloramphenicol, antibacterial macrolides and/or
polypeptide antibiotics) and/or solvents (such as, e.g., water,
acetone, ethanol, isopropanol, butanone and/or ethyl acetate).
[0030] The impression material can exhibit hydrophilic properties,
e.g. if surfactants are added as auxiliary or if polyether groups
are present.
[0031] The impression material can also comprise materials for
adjusting the pH. These preferably include acetic acid, citric
acid, tributyl acetylcitrate, ascorbic acid, acidic fillers, acidic
buffer systems, such as acetic acid/sodium acetate buffer or citric
acid/citrate buffer, and also basic fillers, such as, e.g.,
aluminium hydroxide, basic buffer systems, such as, e.g.,
carbonate/hydrogencarbonate buffer, or basic or acidic ion-exchange
resins.
[0032] According to the invention, the impression material can pass
through a mixer, i.e. the components B and C can, e.g. from a
2-component single-use cartridge, be mixed on a static mixer or a
dispenser (e.g., MixStar.RTM. or Pentamix.RTM.) with a dynamic
mixer and be discharged. Impression materials which can pass
through a mixer in the abovementioned sense generally lie, at the
beginning of the mixing time, according to ISO 4823, in the
consistency range of greater than 26 mm, preferably greater than 30
mm. During and after the mixing of components B and C, the mixture
changes in a first stage, which preferably takes place over a
period of time of at least 15 seconds, particularly preferably 2
minutes, from its relatively thin starting consistency which can
pass through a mixer to a more viscous plastic phase, before it
cures, in a second stage, to give its final elastic form. In the
first stage, the catalyst (e) acts on the chelating groups of the
compound (b) and a ligand exchange reaction takes place which
results in a degree of crosslinking (viscosity). The catalyst is,
for example, an alkoxymetal complex R.sub.4Me, preferably R.sub.4Ti
or R.sub.4Zr, which acts on the .beta.-dicarboxylates or
.beta.-ketoesters. In the second step, complete crosslinking then
takes place by an addition reaction of the organohydropolysiloxanes
(c) with the compound with at least two alkenyl groups (a),
preferably using a platinum catalyst (d). The components are
preferably chosen in such a way that the ligand exchange reaction
and the addition reaction take place at 10 to 40.degree. C., so
that the reactions can be carried out in particular at mouth and
ambient temperature.
[0033] The invention comprises the impression material according to
the invention in all states described, including after the mixing,
in particular after the mixing of components B and C, and the
curing. The mixture in the cured state preferably fulfils the
requirements placed according to ISO 4823 on an elastomeric
impression material in the cured state, such as, for example, the
recovery after deformation.
[0034] According to the invention, the components B and C are
stable on storage for more than 3 months, preferably more than 6
months, more preferably more than 12 months, particularly
preferably more than 24 months. Stable on storage within the
meaning of the present invention means that, under normal storage
conditions (ambient temperature, dry storage), no decline in the
reaction capabilities occurs, in particular no decline in the
reaction capabilities occurs which is accompanied by a
deterioration in the mechanical properties of the impression
material.
[0035] The invention also relates to a process for the preparation
of impressions of objects, an impression of which is to be
taken.
[0036] According to the invention, in the process, in a first step,
the components (a)-(e) of the impression material according to the
invention are mixed, in a second step, the mixture is brought into
contact with a surface of an object, an impression of which is to
be taken, and, subsequently, the impression is removed.
[0037] Preferably, in the first step, the components B and C are
discharged from a container, for example a cartridge, over a mixer
and mixed. During the mixing operation and afterwards, the mixture
changes to a first state, which continues over the processing time
(preferably at least 15 seconds), in which the viscosity of the
impression material is increased (heavy-bodied to putty
consistency), after which an impression is taken of the object, an
impression of which is to be taken. Subsequently, the impression
material changes to a next, solid and elastic state, in which the
impression result is maintained, so that the impression can be
removed from the object.
[0038] The invention is illustrated below with exemplary
embodiments, without limitation on the general nature. The values,
if not further specified, were determined according to ISO
4823.
I. EXAMPLES ACCORDING TO THE INVENTION
Example 1
Preparation of Polydimethylsiloxanes Comprising Chelate Groups
[0039] 500 g of Tegomer HSi 2311
(.alpha.,.omega.-hydroxyalkyl-polydimethylsiloxane, 200 mmol,
Goldschmidt) and 66.3 g of tert-butyl acetoacetate (419 mmol,
Fluka) are heated with stirring in a two-necked flask at
140.degree. C. for 3 h. During this time, tert-butanol produced is
distilled off. The reaction mixture is cooled down and volatile
constituents are removed under vacuum at 0.1 mbar and 55.degree. C.
Yield: 527.54 g. Polydimethylsiloxane modified with acetoacetic
ester (FT-IR, proton NMR).
Example 2
Preparation of Polydimethylsiloxanes Comprising Chelate Groups
[0040] 23.31 g of Tegomer HSi 2311 (9 mmol, Goldschmidt) are
diluted with 20 ml of distilled toluene in a two-necked flask with
a dropping funnel and a CaCl.sub.2 drying tube. 1.52 ml of
distilled pyridine (18 mmol) are added with stirring. 2 ml of ethyl
malonyl chloride (18 mmol, Fluka) are diluted with 5 ml of
distilled toluene in the dropping funnel. This solution is slowly
added dropwise, via the dropping funnel, to the mixture of Tegomer
HSi 2311, pyridine and toluene. After the end of the addition, the
mixture is stirred overnight at AT. The precipitate produced is
filtered off. The organic phase is extracted twice with 10 ml of
saturated NaHCO.sub.3. Subsequently, the organic phase is dried
over Na.sub.2SO.sub.4. Toluene is removed on a rotary evaporator
and the residue is freed from volatile constituents under vacuum at
0.08 mbar and 50.degree. C. Yield: 17.2 g of polydimethylsiloxane
modified with monomethyl malonate (FT-IR, proton NMR).
Example 3
[0041] Each 1 g of polydimethylsiloxane modified with acetoacetic
ester from Example 1 is treated with different amounts of
tetra(n-propyl) zirconate (Tyzor NPZ, Du Pont) according to the
following Examples 3.1, 3.2, 3.3 and 3.4. The viscosity of the
mixture is measured on a rheometer at a shear stress of 500 Pa (DSR
from Rheometrics, geometry: parallel plate, diameter: 25 mm, gap
width: 0.1 mm, temperature: 23.degree. C.).
TABLE-US-00001 Example Example Example Example 3.1 3.2 3.3 3.4 PDMS
modified 1 g 1 g 1 g 1 g with acetoacetic ester Tyzor NPZ -- 0.05 g
0.1 g 0.2 g Viscosity 0.06 0.18 0.63 15 693 [Pa s]
[0042] With an increasing proportion of tetra(n-propyl) zirconate,
more metal atoms are also available which can be complexed by the
chelate groups. Because of this, the molecular weight or the chain
length of the polymers is increased, which is reflected in the
increase in viscosity.
Example 4
Preparation of a Base Paste 1 (B1)
[0043] 17.5% by weight of a vinyl-stopped polydimethylsiloxane (1
65 000 mPas, vinyl content 0.03 mmol/g), 4.3% by weight of a
vinyl-stopped polydimethylsiloxane (1 650 000 mPas, vinyl content
0.02 mmol/g), 2.2% by weight of a methyl-stopped
polydimethylsiloxane (1000 mPas), 0.2% by weight of a
polyhydromethyl-siloxane (230 mPas, SiH content 2.3 mmol/g), 0.6%
by weight of a polyhydromethylsiloxane (40 mPas, SiH content 4.3
mmol/g), 3.9% by weight of petrolatum, 6.0% by weight of paraffin
and 10% by weight of polydimethylsiloxane modified with acetoacetic
ester from Example 1 according to the invention are introduced into
a laboratory mixer. 16.5% by weight of diatomaceous earth, 37.2% by
weight of powdered hydrophobized cristobalite, 1% by weight of
hydrophobized pyrogenic silica (BET specific surface 140 m.sup.2/g)
and 0.6% by weight of an ultramarine pigment are incorporated in
this mixture and the mixture is stirred until homogeneous.
Example 5
Preparation of a Catalyst Paste 1 (C1)
[0044] 5.7% by weight of a vinyl-stopped polydimethylsiloxane (1000
mPas, vinyl content 0.13 mmol/g), 12.7% by weight of a
vinyl-stopped polydimethylsiloxane (65 000 mPas, vinyl content 0.03
mmol/g), 5.7% by weight of a vinyl-stopped polydimethylsiloxane (1
650 000 mPas, vinyl content 0.02 mmol/g), 2.4% by weight of a
methyl-stopped polydimethylsiloxane (1000 mPas), 3.8% by weight of
petrolatum, 5.7% by weight of paraffin, 15.1% by weight of
diatomaceous earth, 41.9% by weight of powdered hydrophobized
cristobalite, 0.18% by weight of titanium dioxide, 0.02% by weight
of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 0.8% by weight of a
platinum catalyst, dissolved in a vinyl-stopped
polydimethylsiloxane (1000 mPas, vinyl content 0.13 mmol/g,
platinum content of the solution=2% by weight), and 6.0% by weight
of tetra(n-propyl) zirconate (Tyzor NPZ, Du Pont) are mixed in a
laboratory mixer until homogeneous.
Example 6
Preparation of a Catalyst Paste 2 (C2)
[0045] 5.7% by weight of a vinyl-stopped polydimethylsiloxane (1000
mPas, vinyl content 0.13 mmol/g), 12.7% by weight of a
vinyl-stopped polydimethylsiloxane (65 000 mPas, vinyl content 0.03
mmol/g), 5.6% by weight of a vinyl-stopped polydimethylsiloxane (1
650 000 mPas, vinyl content 0.02 mmol/g), 2.4% by weight of a
methyl-stopped polydimethylsiloxane (1000 mPas), 3.8% by weight of
petrolatum, 5.7% by weight of paraffin, 15.1% by weight of
diatomaceous earth, 41.8% by weight of powdered hydrophobized
cristobalite, 0.18% by weight of titanium dioxide, 0.02% by weight
of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 0.8% by weight of a
platinum catalyst, dissolved in a vinyl-stopped
polydimethylsiloxane (1000 mPas, vinyl content 0.13 mmol/g,
platinum content of the solution=2% by weight), and 6.2% by weight
of tetra(n-butyl) titanate (Tyzor TnBT, Du Pont) are mixed in a
laboratory mixer until homogeneous.
Example 7
[0046] When mixed by hand (mixing on a smooth support using a
standard dental spatula), the following values were determined for
the pastes B1, C1 and C2 of Examples 4-6 according to the invention
and the mixtures thereof:
Consistency B1: 31 mm
Consistency C1: 32 mm
Consistency C2: 33 mm
[0047] Mixed consistency 5 parts B1+1 part C1: 21 mm Mixed
consistency 5 parts B1+1 part C2: 22.5 mm Processing latitude 5
parts B1+1 part C1: 3:15-3:30 min:sec (incl. 1 min mixing time)
Processing latitude 5 parts B1+1 part C2: 3:00 min:sec (incl. 1 min
mixing time) Setting time 5 parts B1+1 part C1: 4:30 min:sec (incl.
1 min mixing time) Setting time 5 parts B1+1 part C2: 4:00-4:15
min:sec (incl. 1 min mixing time)
[0048] The following values were determined from the cartridge:
[0049] from cartridge (5 parts B1+1 part C2) with 15 mm/min
(MixStar.RTM. mixing system, DMG) feeding: maximum temperature on
mixing: 31.5.degree. C. [0050] from cartridge (5 parts B1+1 part
C2) with 24 mm/min feeding (Pentamix.RTM., 3M ESPE): maximum
temperature on mixing: 31.5.degree. C.
Example 8
Preparation of a base paste 2 (B2)
[0051] 24.1% by weight of a vinyl-stopped polydimethylsiloxane (65
000 mPas, vinyl content 0.03 mmol/g), 0.7% by weight of a
polyhydromethylsiloxane (40 mPas, SiH content 4.3 mmol/g), 3.9% by
weight of petrolatum, 6.1% by weight of paraffin and 10% by weight
of polydimethylsiloxane modified with acetoacetic ester from
Example 1 are introduced into a laboratory mixer. 16.5% by weight
of diatomaceous earth, 38.1% by weight of powdered hydrophobized
cristobalite and 0.6% by weight of an ultramarine pigment are
incorporated in this mixture and the mixture is stirred until
homogeneous.
Example 9
Preparation of a Catalyst Paste 3 (C3)
[0052] 8.0% by weight of a vinyl-stopped polydimethylsiloxane (1000
mPas, vinyl content 0.13 mmol/g), 12.7% by weight of a
vinyl-stopped polydimethylsiloxane (65 000 mPas, vinyl content 0.03
mmol/g), 5.6% by weight of a vinyl-stopped polydimethylsiloxane (1
650 000 mPas, vinyl content 0.02 mmol/g), 3.8% by weight of
petrolatum, 5.6% by weight of paraffin, 15.1% by weight of
diatomaceous earth, 42.2% by weight of powdered hydrophobized
cristobalite, 0.02% by weight of
1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 0.78% by weight of a
platinum catalyst, dissolved in a vinyl-stopped
polydimethylsiloxane (1000 mPas, vinyl content 0.13 mmol/g, Pt
content of the solution=2% by weight), and 6.2% by weight of
tetra(n-butyl) titanate (Tyzor TnBT, Du Pont) are mixed in a
laboratory mixer until homogeneous.
Example 10
[0053] When mixed by hand, the following values were determined for
the pastes B2 and C3 of Examples 8 and 9 according to the invention
and the mixture thereof:
Consistency B2: 29.5 mm
Consistency C3: 34 mm
[0054] Processing latitude 5 parts B2+1 part C3: 4:45 min:sec
(incl. 1 min mixing time) [0055] Setting time 5 parts B2+1 part C3:
4:45-5:00 min:sec (incl. 1 mixing time) Shore A after 24 h 5 parts
B2+1 part C3: 36
[0056] The following values were determined from the cartridge:
From cartridge (5 parts B2+1 part C3) with 15 mm/min feeding:
Processing latitude: 3:30 min:sec (incl. 1 min mixing time) Setting
time: 5:00 min:sec (incl. 1 min mixing time) Lasting deformation:
1.3% Deformation under pressure: 6.3% Mixed consistency: 24 mm
Maximum temperature on mixing: 31.0.degree. C. As clear from the
values determined for Examples 7 and 10, the base and catalyst
pastes according to the invention are suitable for manual mixing
and for use in conventional cartridges and exhibit processing
parameters such as are desired in particular in dental
applications.
II. Comparative Examples
Not According to the Invention
[0057] Base and catalyst pastes for an impression material which
crosslinks by addition not according to the invention are prepared
as follows:
Example 11
Preparation of a base paste 1 (B1)
[0058] 19.0% by weight of a vinyl-stopped polydimethylsiloxane
(1000 mPas, vinyl content 0.13 mmol/g), 21.7% by weight of a
vinyl-stopped polydimethylsiloxane (10 000 mPas, vinyl content 0.05
mmol/g), 10.9% by weight of a methyl-stopped polydimethylsiloxane
(10 mPas), 6.0% by weight of a polyhydromethylsiloxane (230 mPas,
SiH content 2.3 mmol/g), 0.2% by weight of an ultramarine pigment,
4.3% by weight of a hydrophobized pyrogenic silica (BET specific
surface 140 m.sup.2/g) and 37.9% by weight of a powdered
hydrophobized cristobalite are mixed in a laboratory mixer until
homogeneous.
Example 12
Preparation of a Catalyst Paste 1 (C1)
[0059] 22.4% by weight of a vinyl-stopped polydimethylsiloxane
(1000 mPas, vinyl content 0.13 mmol/g), 22.4% by weight of a
vinyl-stopped polydimethylsiloxane (10 000 mPas, vinyl content 0.05
mmol/g), 11.2% by weight of a methyl-stopped polydimethylsiloxane
(10 mPas), 0.3% by weight of a platinum catalyst, dissolved in a
vinyl-stopped polydimethylsiloxane (1000 mPas, vinyl content 0.13
mmol/g, Pt content of the solution=2% by weight), 4.5% by weight of
a hydrophobic pyrogenic silica (BET specific surface 140 m.sup.2/g)
and 39.2% by weight of a powdered hydrophobic cristobalite are
mixed in a laboratory mixer until homogeneous.
Example 13
Preparation of a Base Paste 2 (B2)
[0060] 92.5% by weight of the base paste 1 from Example 11 was
mixed in a laboratory mixer with 7.5% by weight of the
polydimethylsiloxane comprising amino groups Tego IS 4111
(Goldschmidt) until homogeneous.
Example 14
Preparation of a Catalyst Paste 2 (C2)
[0061] 92.5% by weight of the catalyst paste 1 from Example 12 was
mixed in a laboratory mixer with 7.5% by weight of the
polydimethylsiloxane comprising amino groups Tego IS 4111 until
homogeneous.
Example 15
Cross Experiments with the Pastes B1, C1, B2 and C2 of Examples
11-14
[0062] In a cross experiment, the base and catalyst pastes B1, C1,
B2 and C2 of the abovementioned Comparative Examples 11-14 were
mixed in the ratio by weight 1:1 and the processing latitude and
the setting time after preparation and also after storage at
23.degree. C. were determined (see following table). In these
tests, the influence of the amino functional group on silicones
which crosslink by addition is to be investigated.
TABLE-US-00002 after preparation after storage.sup.a) Processing
Setting Processing Setting Combination latitude.sup.b) time.sup.c)
latitude.sup.b) time.sup.c) B1 + C1 3:15 4:30 2:45-3:00 4:00
(control) min:sec min:sec min:sec min:sec B1 + C2 not ca. ca.
<16 h determined 180 min 120 min B2 + C1 not no curing not no
curing determinable determinable B2 + C2 not no curing not no
curing determinable determinable .sup.a)Duration of storage 83 days
.sup.b)incl. 1:00 min:sec mixing time, measured at 23.degree. C.
.sup.c)incl. 1:00 min:sec mixing time, measured at 32.degree.
C.
[0063] The following conclusions can be drawn from the tests of the
cross experiment:
[0064] If the catalyst paste comprises a compound with amino groups
(C2), a hardening takes place which is clearly slowed down (B1+C2)
or hardening does not take place at all (B2+C2), with reference to
the control not comprising amino groups (B1+C1). The cause is
assumed to be an interaction, mentioned at the start, of the amino
groups with the Pt atom of the platinum catalyst, so that the
hydrosilylation of the vinyl groups proceeds only very slowly. If
the base paste comprises a compound with amino groups (B2), the
mixed pastes no longer cure (B2+C1 and B2+C2).
Example 16
Preparation of a Base Paste 3 (B3)
[0065] The base paste 3 of the present Comparative Example 16
corresponds, in the preparation and composition, to the base paste
1 of Example 4 according to the invention, with the difference that
the 10% by weight of the polydimethylsiloxane modified with
acetoacetic ester has been replaced by the polydimethylsiloxane
modified with amino groups Tego IS 4111.
Example 17
Preparation of a Catalyst Paste 3 (C3)
[0066] The catalyst paste 3 of the present Comparative Example 17
corresponds, in the preparation and composition, to the catalyst
paste 1 of Example 5 according to the invention.
Example 18
[0067] When mixed by hand, the following values were determined for
the pastes B3 and C3 of Comparative Examples 16 and 17 and the
mixture thereof
Consistency B3: 29 mm
Consistency C3: 36 mm
[0068] Mixed consistency 5 parts B3+1 part C3: 20 mm Processing
latitude 5 parts B3+1 part C3: 3: not ascertainable (incl. 1 min
mixing time) Setting time 5 parts B3+1 part C3: >40 min (incl. 1
min mixing time)
[0069] In contrast to the mixtures of Examples 7 and 10 according
to the invention, no useable two-stage curing mechanism could be
detected in the present comparative example after the mixing of the
two pastes B3 and C3. The processing latitude is undetectable and
the setting time is too slow.
* * * * *