Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2002-01-22
2004-12-28
Yoon, Tae H. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C528S028000, C433S228100
Reexamination Certificate
active
06835760
ABSTRACT:
The invention relates to the use of mixtures as impression or doubling compositions in the dental area.
Impression compositions, which are used in the dental area, are known (cf. R. G. Craig, Restorative Dental Materials, The C. V. Moosbe-Comp. St. Louis, Toronto, London, 1980, page 1979 ff). Such materials must satisfy high requirements.
1. Pleasant odor and taste and an esthetic appearance.
2. The compositions may not contain any toxic or irritating components.
3. The compositions must have a shelf life of several months.
4. It must be possible to produce the compositions economically and the impression must be precise.
5. The compositions must be easily handled.
6. The curing characteristics must correspond to clinical requirements.
7. The cured compositions must be elastic and, when stressed in tension, must not be deformed permanently.
8. The cured compositions must have a sufficient compressive strength and must not break.
9. At room temperature and normal humidity, the cured compositions must be dimensionally stable until, after an appropriate time, accurate plaster impressions can be prepared.
10. The cured compositions must not cause any damage to the plaster and must be compatible with other impression compositions.
The impression compositions, which are based on alkoxysilyl-functionalized polyethers, are described in EP 0 269 819 B1.
The use of mixtures is disclosed there, which contain
A) a polyaddition product, containing ether, urethane, and urea groups and terminal alkoxysilane groups, with a predominantly linear molecular structure, exclusively aliphatic or cycloaliphatic bound ether, urethane and urea segments, with an average molecular weight Mn of 800-2000, characterized by the
a) a 25 to 90 percent by weight content of polyether groups,
b) a 0.5 to 10 percent by weight content of urethane groups (—NH—CO—O—),
c) a 0.5 to 10 percent by weight content of urea groups (—NH—CO—NH—) and
d) terminal groups having the formula —NR—(CH
2
)
n
—SiR
1
R
2
R
3
,
in which n represents the numbers 1 to 6,
R represents hydrogen or —(CH
2
)
n
—SiR
1
R
2
R
3
,
R
1
R
2
R
3
independently of one another represent C1 to C4 alkoxy, the terminal —SiR
1
R
2
R
3
alkoxysilyl group content being 1 to 25 percent by weight and
B) a mixture containing water and organic and/or inorganic acids in a ratio by weight of 1:0.01 to 1:40 as impression or doubling compositions in the dental area.
However, these systems do not fulfill all of the requirements, mentioned above, to the desired extent.
These impression compositions must be synthesized especially by expensive, multi-step methods. Moreover, these products are highly viscous, since diisocyanates are reacted with dihydroxypolyethers, so that there necessarily is an increase in the average molecular weight (Mn) and, with that, also an increase in viscosity. With that, the possibilities of formulating pasty compositions with the polyaddition products, known from the art, is greatly limited, since either high diluent contents or low filler contents must be selected in order to obtain compositions, which can be processed and therefore are not too viscous.
Finally, the impression compositions based on the polyaddition product described in EP 0 269 819 B1, when mixed with water and acid, have unfavorable curing kinetics, which are characterized by a short processing time and, at the same time, by a long setting time.
In the DE 44 39 769, synthetic products are disclosed with a polyaddition product, containing at least one silane, ether and urethane group, with a predominantly linear molecular structure with aliphatic or cycloaliphatic, bound ether or urethane segments and a number average molecular weight ranging from 800 to 20,000, the polyaddition product having the following distinguishing features:
a) a polyether group content of 20 to 90 and especially of 50 to 80 parts by weight, based on 100 parts by weight of polyaddition product,
b) a content of urethane groups of Formula I
—NH—CO—O (I)
of 0.5 to 10 and especially of 1 to 8 parts by weight, based on 100 parts by weight of polyaddition product,
c) as well as a content of terminal alkoxysilyl groups of Formula II
—NR—(CH
2
)
m
—SiR
1
R
2
R
3
(II)
in which
m is a number ranging from 1 to 6 and especially 3,
R is hydrogen or a group of Formula (III)
—(CH
2
)
m
—Si R
1
R
2
R
3
(III)
in which m, R
1
, R
2
and R
3
have the meanings given and at least one of the groups R
1
, R
2
and R
3
is a group of Formula IV
—(O—C
p
H
2p
)
q
—O—R
4
(IV)
in which
p is a number from 2 to 4 and especially 3 and
q represents a number of from 1 to 100 and especially 2 to 4 and
R
4
represents an alkyl, aralkyl, vinyl, vinylcarbonyl, &agr;-methylvinylcarbonyl or &bgr;-methylvinylcarbonyl group,
in which the remaining R
1
, R
2
and R
3
groups represent methyl, ethyl or C
1
to C
4
alkoxy, insofar as they are not groups defined above,
and the synthetic materials furthermore contain at least one catalyst for the condensation of the silane groups.
An expensive, multi-step synthesis methods, which requires a transesterification step of commercially obtainable silanes with compounds having the structure H—(O—C
p
H
2p
)
q
—O—R
4
is also a disadvantage of this system. The high toxic potential of the groups of the general formula H—(O—C
p
H
2p
)
q
—OR
4
is a further disadvantage of this system.
It is an object of the present invention to avoid the disadvantages of the known impression compositions based on alkoxysilyl-functional polyethers, that is, especially to make available impression compositions based on commercially obtainable or easily synthesized (preferably in one step), low viscosity (viscosity<50 Pas) alkoxysilyl-functional polyethers, which are distinguished by advantageous setting kinetics (that is, processing times of 2 to 3 minutes and curing times of less than 4 minutes), that is, by a so-called snap-set behavior (slow induction time of up to several minutes and, subsequently, very rapid setting).
Pursuant to the invention, this objective is accomplished by a use described in claim
1
.
It is a question here of the use of mixtures containing
A) alkoxysilyl-functional polyethers with linear or branched main chains with an average molecular weight (Mn) of 800 to 20,000, containing 20 to 95 percent of polyether groups and
0.2 to 25 percent of SiR
1
R
2
R
3
alkoxysilyl groups, in which R
1
, R
2
and R
3
, independently of one another, are hydrogen, alkyl or alkoxy, and
0 to 10 percent of urethane groups or 0 to 10 percent of urea groups, and
B) a mixture, containing water and organic and/or inorganic acids in a ratio by weight of 1:0.01 to 1:40,
as impression or doubling composition in the dental area.
In further embodiments of the invention
2. mixtures are used, the component A) of which has a branched main chain;
3. mixtures are used, the component A) of which is free of urethane groups;
4. mixtures are used, the component A) of which has an average molecular weight of 1500 to 15,000;
5. mixtures are used, the component A) of which contains 2 to 15 percent of SiR
1
R
2
R
3
alkylsilane groups.
Some of the alkoxysilyl-functional polyethers, which are used pursuant to the invention, such as the MS polymer of the Kanaka Corporation, are commercially available. These are polypropylene oxide derivatives, which are functionalized with methyldimethoxysilyl groups (such as MS Polymer S303H).
Furthermore, polyethers, which are used pursuant to the invention, can be synthesized in that linear or branched polyether polyols or linear or branched, amino-terminal polyethers are reacted with suitably functionalized alkoxysilanes and optionally with polyisocyanates at temperatures of 20° to 150° C. The use of a catalyst may be necessary for this reaction.
Suitable for the preparation of the inventive alkoxysilyl-functional polyethers are, for example, polyether polyols, which are known from the production of polyurethanes (for example, Ullmann's Encyclopedia of Industrial Chemistry, vol. 21, pp. 665 to 717, VCH Publishers Inc., 1992 or U.S. Pat. No. 5
Freckmann Michael
Schaub Matthias
Urbas Holger
Heraues Kulzer GmbH & Co. KG
Norris McLaughlin & Marcus PA
Yoon Tae H.
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