Impression compositions comprising triglycerides

Details Impression compositions comprising triglycerides Impression compositions comprising triglycerides

2000-04-06

2002-05-28

Szekely, Peter (Department: 1714)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Processes of preparing a desired or intentional composition...

C433S214000, C524S313000, C524S612000

Reexamination Certificate

active

06395801

ABSTRACT:

The present invention relates to rubber-elastic impression or duplicating compositions which are based on vulcanizable polyether materials and are used, in particular, in the dental field, and also in orthopedics. In particular, the present invention describes vulcanizable polyether pastes with aziridino end groups, addition-crosslinking polyether silicone pastes with H—Si groups, and polyether acrylate and methacrylate pastes which can be vulcanized by free radicals, for the production of accurate impressions of jaws with teeth, some teeth or no teeth and of gypsum models.
DE-B-17 45 810 discloses impression compositions of polyether materials with aziridino end groups. DE-A1-37 41 575 and DE-A1-38 38 587 disclose impression compositions based on polyether materials with alkenyl groups and polyorganosiloxane radicals containing H—Si groups, which polymerize under the action of platinum catalysts. EP-A2-0 173 085 discloses impression compositions of polyether materials with acrylate and methacrylate groups which, after irradiation with light of suitable wavelength, polymerize—under initiation by the dissociation of a photoinitiator. DE-A1-43 06 997 furthermore discloses impression compositions based on polyether materials which are hydrophilized by additives. These materials have a good capacity for flowing on hydrophilic oral surfaces and therefore have a higher impression sharpness for these applications than other known impression compositions, e.g. based on conventional hydrophobic silicones.
To simplify processing of these impression compositions, thixotropic agents, such as highly disperse fillers, e.g. described in DE-A1-43 21 257, or fats of various origins, e.g. described in DE-A1-43 06 997, are added to them. DE-A1-195 05 896 furthermore describes the addition of hydrogenated beef tallow to aziridine-free impression materials. It is known that these thixotropic agents should not exceed a proportion by weight of approx. 10% in polyether materials with aziridino end groups, so that the mechanical properties of the cured impression composition is not adversely influenced. This means that the proportion of aziridino-containing polyethers of such impression compositions must lie in the range from 50 to 70 per cent by weight, which therefore leads substantially to these materials becoming more expensive. Another disadvantage of admixing the thixotropic agents used to date is that the viscosity of polyether pastes comprising such thixotropic agents increases constantly in the course of storage, and the usable life of these materials is therefore adversely restricted. Pastes without these thixotropic agents show no tendency to thicken.
The object of the present invention is to provide impression compositions which are based on polyethers and comprise thixotropic agents, which can be admixed in amounts of >10 percent by weight without the mechanical properties of the cured compositions being adversely influenced. Furthermore, the impression compositions prepared with these thixotropic agents should show the lowest possible increase in viscosity with increasing storage time.
The object is achieved by impression compositions which are characterized in that they comprise
a) approx. 30 to 70 wt. % of aziridino-polyether,
b) approx. 5 to 20 wt. % of a triacyl glyceride of non-animal origin which has a stearoyl content of >70 wt. %, based on the acyl content of the triacyl glyceride, or, in the case of a lower stearoyl content and if this adversely influences the storage stability of the impression composition, has been esterified in itself beforehand, and
c) approx. 10 to 65 wt. % of customary catalysts, auxiliaries and additives,
in each case based on the total weight of the ready-mixed composition.
The impression compositions according to the invention preferably comprise 30 to 40 wt. % of component a), 5 to 20 wt. % of component b) and 40 to 65 wt. % of component c), in each case based on the total weight of the ready-mixed composition.
Impression compositions of this combination are distinguished, compared with the polyether impression materials which are known to date and are based on aziridine, by consistently good mechanical properties of the completely vulcanized and polymerized materials (see examples 1 and 4 and table 1), with a significantly lower content of aziridino-polyether at the same time. As a result, the compositions according to the invention can be produced considerably less expensively.
In addition, the impression compositions can be mixed more easily by the use of triacyl glycerides of non-animal origin according to component b), and therefore allow a shorter production time. Surprisingly, it has been found that by the addition of the triacyl glycerides described, the compositions according to the invention show no substantial increase in the viscosity over a period of up to 24 months during storage, even at elevated temperature (examples 1 to 4; and table 1). However, this effect can preferably be achieved with those triacyl glycerides of non-animal origin in which the stearoyl content is greater than or equal to 70 wt. %, based on the acyl content of the triacyl glyceride. If triacyl glycerides in which the stearoyl content is less than 70 wt. %, based on the acyl content of the triacyl glyceride, are used in the compositions according to the invention, a thickening is sometimes observed during storage, especially at elevated temperature (comparison examples 1 to 4; and table 1). But if such triacyl glycerides are pretreated by interesterification (esterification in themselves), as described in preparation example 2, before being admixed to the impression composition, the polyether impression compositions produced therefrom surprisingly show no substantial increase in the viscosity during storage at elevated temperature (example 2 and table 1). However, triacyl glycerides in which the stearoyl content is <70 wt. % can also be employed if the storage stability of the impression composition is not adversely influenced as a result.
The esterification in the fat itself can be carried out in principle by stirring the fat with a strong base and subsequent neutralization (in this context, see also “Ullmann's Encyclopaedia of Industrial Chemistry”, 5
th
ed., volume A10, p. 209).
A large number of triacyl glycerides can therefore be used for preparation of the compositions according to the invention, such as e.g. avocado oil, cottonseed oil, groundnut oil, cacao butter, pumpkin seed oil, linseed oil, maize germ oil, olive oil, palm oil, rice oil, rapeseed oils, safflower oil, sesame oil, soya oil, sunflower oil, grapeseed oil, wheatgerm oil, borneo tallow, fulwa tallow, hemp oil, illipé butter, lupin-oil, candlenut oil, kapok oil, katiau fat, kenaf seed oil, kekuna oil, poppy oil, mowrah butter, okra oil, perilla oil, sal butter, shea butter and tung oil, if these fats have been hydrogenated before their use. Hydrogenated fats which are regarded as suitable are those which have an iodine number (measured in accordance with the standard DGF C-V 11b) of less than 20. Particularly preferred fats are those which have an iodine number of less than 5. Fat hydrogenations are carried out, for example, as described in “Ullmanns Enzyklopädie der industriellen Chemie [Ullmann's Encyclopaedia of Industrial Chemistry]”, 4th ed., volume 11, p. 469. Mixtures of these naturally occurring fats as well as synthetically produced fats, such as e.g. Softisan 154 or Dynasan 118 (Hüls) can also be used. The preparation of such synthetic triacyl glycerides is relatively simple for the expert and can be carried out, for example, from glycerol and the corresponding fatty acid methyl esters. Such esterification reactions are described, inter alia, in “Houben-Weyl, Methoden der Organischen Chemie [Methods of Organic Chemistry]”, vol. E5/part 1, p. 659 et seq.
Preferred triacyl glycerides correspond to the following formula
in which R
1
, R
2
and R
3
independently of one another denote C
11
H
23
CO, C
13
H
27
CO, C
15
H
31
CO or C
17
H
35
CO, the pro

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