Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Patent
1996-02-23
1999-03-16
Glass, Margaret
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
528 18, 549215, C08G 7708
Patent
active
058832149
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Silicones and siloxanes can be employed for flexibilizing reactive resins. To obtain a chemically stable molded material, those siloxanes which participate in the curing reaction of the reactive resin and are incorporated chemically into the molded material are preferred.
Siloxanes which contain epoxide groups and can be bonded into a molded material in a stable and hydrolysis-resistant manner with the epoxide group via SiC bonds are therefore sought for mixing with epoxy resins.
Epoxysilanes having epoxide groups bonded via SiC are obtained by hydrosilylation of silane hydrides with unsaturated epoxide compounds. Under technologically demanding conditions, with exclusion of water and in an absolute inert gas atmosphere, reaction products can be obtained which must be worked up in expensive purification steps and must be freed from the platinum metal group catalyst required.
Epoxysilanes can also be rendered accessible by epoxidation of unsaturated silane compounds. This is also an involved synthesis which leads to expensive products.
The object of the present invention is therefore to provide a simple process for the preparation of epoxysilanes having epoxide groups bonded via SiC, which leads to a product which is stable to chemicals and heat, has an adequate epoxide content, is compatible with the usual epoxy resins for casting resin applications and can be cured together with these. SUMMARY OF THE INVENTION
SUMMARY OF THE INVENTION
This object is achieved according to the invention by a process having the features of claim 1. Further embodiment of the invention and a preferred use for the process product are to be found in the other claims.
The process accordinig to the invention can be carried out in a simple one-pot reaction in a short time under normal condition with respect to atmosphere and pressure with minimum expenditure on the process. A mixture of various siloxanes which comprises chiefly cyclic tri- and tetrameric condensation products is obtained as the product. If the reaction conditions remain constant, the process can be carried out reproducibly. Transparent oils which result in transparent molded materials when mixed with corresponding resin components can be obtained in the process. The product is compatible with the usual epoxy resins and can be mixed with them in all proportions as a further resin component without further purification or working up. The epoxide value of the resulting siloxanes, predetermined by the nature and the ratio of the amounts of the starting substances, results in a product which is readily capable of crosslinking. This can be stored for several months with only a slight increase in viscosity and only a slight reduction in the epoxide value. It has a high stability to heat and thermal oxidation, which is also retained in the molded material obtained after curing of a corresponding mixture with the usual epoxy resins.
During the condensation reaction, an Si--O--Si bond is formed from the alkoxy group of the epoxysilane and the OH group of the silanol, the corresponding alkyl alcohol being split off. Various homocondensation products of the silanol are observed as a side reaction. However, the predominant fraction of the siloxane mixture obtained as the product comprises the trimeric and tetrameric condensation products mentioned containing epoxide groups, in which the ratio of cyclic to linear products can be adjusted according to the reaction procedure and is, for example, 2:1. By-products which are obtained by reaction of the epoxide groups with the starting substances, intermediates or end products are also obtained to a small extent. ##STR1##
The epoxyalkoxysilane 1 employed as the starting compound carries 1 to 3 alkoxy groups which are capable of condensation. The radical R1 can be chosen as desired, but is preferably an alkyl radical having 1 to 6 C atoms, since the reactivity of the group to be split off during the condensation decreases as the chain length of the alkyl radical increases. The most reactive starting comp
REFERENCES:
patent: 3455877 (1969-07-01), Plueddemann et al.
patent: 3563941 (1971-02-01), Plueddemann et al.
patent: 3647846 (1972-03-01), Hartlein et al.
patent: 4902739 (1990-02-01), Ona et al.
patent: 5109094 (1992-04-01), Rees et al.
patent: 5292849 (1994-03-01), Fujioka et al.
patent: 5300608 (1994-04-01), Chu et al.
White, et al., "Organofunctional Siloxanes", Chapter 4, p. 193-210, Siloxane Polymers, Simon & Schuster Co., Englewood Cliffs, NJ, 1993.
Wipfelder, et al., "Epoxysiloxane Resins by the Condensation of 3-Glycidloxypropyltrimethyoxysilane with Diphenylsilanediol", Die Angewandte Makromolekulare Chemie 218, pp. 111-126, 1994.
Rudiger Nass, et al., J. Non-Cryst. Solids, 121, 370-374 (1990).
G. Philipp et al., J. Non-Cryst. Solids, 82, 31-36 (1986).
Hohn Klaus
Wipfelder Ernst
Glass Margaret
Siemens Aktiengesellschaft
LandOfFree
Process for the preparation of epoxysilanes does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the preparation of epoxysilanes, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the preparation of epoxysilanes will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-818648