Storage-stable polysiloxane composition which gives permanently

Details Storage-stable polysiloxane composition which gives permanently Storage-stable polysiloxane composition which gives permanently

1994-02-10

1996-12-03

Marquis, Melvyn I.

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

Synthetic resins

At least one aryl ring which is part of a fused or bridged...

528 15, 524264, 524267, 524263, 525478, C08L 8304

Patent

active

055809219

DESCRIPTION:

BRIEF SUMMARY
Storage-stable polysiloxane composition which gives permanently water-wettable vulcanizates
The present invention relates to storage-stable polysiloxane compositions which give, after vulcanization, permanently water-wettable elastomers, a process for the preparation of a hydrophilic modifier for the polysiloxane compositions, and their use as dental impression compositions.
Polysiloxane compositions which vulcanize to give elastomers are widely used as impression compositions. The addition-crosslinking systems have proved to be particularly suitable for this application, since they set faster and, in contrast to the condensation-crosslinking systems, do not require large amounts of problematical catalyst.
A considerable disadvantage of silicone impression preparations based on hydrophobic polysiloxanes is based on the fact that a precise impression of moist surfaces, such as the tissue, tooth or dental prosthesis surfaces in the oral cavity, is scarcely possible since, because of the high surface tension of water, the moisture contents try to achieve a shape with the lowest surface area. The moisture is therefore deposited in the form of drops between the surface of which an impression is to be made and the impression composition.
A surface-active impression composition causes the moisture contents to spread over the surfaces of which an impression is to be made, to form a thin film of moisture. Hollow cavities in the impression are thereby avoided, and a precise reproduction of the surface structure is achieved.
The preparation of water-wettable silicone impression compositions by mixing polysiloxane compositions with surface-active agents of relatively low molecular weight is known: the use of nonylphenoxy-poly(ethyleneoxy)ethanol is described in K. B. Norling, M. H. Reisbick; The Journal of Prosthetic Dentistry 42, 342-347 (1979), the use of proteins, hydrophilic silicone oils and nonionic surface-active agents is described in DE-A-37 21 784 (S. Futami and S. Terauchi; laid open on 21.1.1988 for G-C Dental Industrial Corp., Tokyo, JP), and the use of siloxane components having alkylene ether groups in polysiloxane compositions is described in EP-A-231 420 (H. Gribi; laid open on 12.8.1987 for Dentsply GmbH, Konstanz, DE ).
The above impression compositions have the disadvantage that the surface-active agents sometimes have a tendency to demix from the impression compositions, migrate to the surface thereof or are extracted in contact with aqueous media due to the poor bonding in the impression compositions. In the last case, the water-wettability is lost by, for example, rinsing with water, disinfection, sterilization or production of duplicates with the aid of impression preparations containing water, such as gypsum, before the desired application aims, such as reproducible wetting properties of the silicone impression after removal from the moist surface, are achieved.
Organosiloxane/alkylene ether copolymers dissolved in water or in a water-soluble organic solvent are known as anti-fogging agents from DE-A 1 519 412 (E. L. Morehouse; laid open on 21.5.1970 for Union Carbide Corp., New York, U.S.A. ), it being possible for the copolymers to contain aliphatic double bonds or Si--H groups.
According to the preparation process described therein, alkylene ether groups containing allyl end groups are reacted with dichloromethylsilane in a hydrosilylation reaction in the presence of a platinum catalyst. The product is then hydrolyzed with silanes containing vinyl groups, Si--H groups and chlorine and methyl groups to give the copolymers.
The bonding of polyether units to one of the components of the polysiloxane base composition, inter alia, is proposed for silicone impression compositions in EP-A-231 420. Permanently water-wettable vulcanizates can be obtained by the polyether units being crosslinked in.
However, the siloxane components having alkylene ether groups which are described in EP-A-231 420 and which improve the wettability and can be mixed with the polysiloxane composition, and the polysiloxane

REFERENCES:
patent: 3337351 (1967-08-01), Morehouse et al.
patent: 3839388 (1974-10-01), Nitzsche et al.
patent: 3933880 (1976-01-01), Bergstrom et al.
patent: 4677161 (1987-06-01), Suzuki et al.
patent: 4778832 (1988-10-01), Futami et al.
patent: 5008229 (1991-04-01), Schuster et al.
"The Journal of Prosthetic Dentistry", by Barry K. Norling and Morris H. Reisbick, 42, pp. 342-347 (1979).
"Chemie und Technologie der Silicone", Verlag Chemie Weinheim, 2nd edition 1968 p. 163ff.
"Chemistry and Technology of Silicones", Academic Press, Inc., Orlando Florida 32887, 1968, p. 191ff.
"Berichte der deutschen chemischen Gesellschaft", 57, 1924, pp. 1343-1355.

Affiliated with

Also associated with

Rating

Storage-stable polysiloxane composition which gives permanently does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Storage-stable polysiloxane composition which gives permanently , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Storage-stable polysiloxane composition which gives permanently will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-786181