Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Patent
1998-03-12
2000-12-19
Wood, Elizabeth D.
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
502152, 528 18, B01J 3100, C08G 7706, C08G 7708
Patent
active
061627569
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to novel tin catalysts, to a process for the production thereof and use thereof and to crosslinkable mixtures containing these novel tin catalysts.
It is generally known to use organotin compounds as catalysts in condensation-crosslinking 1 and 2 component polysiloxane compositions, hereinafter referred to as RTV-1 or RTV-2 (room temperature vulcanising component 1 or 2) compositions, which cure to yield elastomers by the action of water or on absorption of atmospheric humidity.
Diorganyltin compounds, such as dialkyltin dicarboxylates or the reaction products thereof with alkoxysilanes are conventionally used as catalysts in polysiloxane compositions. Examples of such compounds are, inter alia, dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dioctyltin dioctoate, dioctyltin dilaurate or reaction products of dibutyltin oxide with silicic acid esters, such as polymethyl silicate, tetraethoxy silicate and polyethyl silicate.
U.S. Pat. No. 3,525,778 additionally describes organophosphatostannanes of the general formula products are distinguished by elevated activity and result in rapid curing of the polysiloxane compositions.
However, when used in polysiloxane compositions, tin catalysts known from the literature exhibit the disadvantage that they not only have the desired catalytic action on the condensation reaction but they also bring about unwanted polymer degradation reactions. This results, for example, in the loss or a retardation of the crosslinking properties of RTV-1 products. Polymer degradation reactions may also occur in RTV-2 products, in which the catalyst is usually stored in a separate component and mixed with the other component only shortly before use of the product. The consequences of this are, inter alia that the catalyst component, in particular in pasty formulations, is degraded during storage and viscosity falls undesirably or the reactivity changes.
The object of the present invention was to provide tin catalysts which do not exhibit the disadvantages of known products and are suitable as catalysts for RTV-1 or RTV-2 compositions.
It has surprisingly been found that reaction products of organotin compounds with orthophosphoric acid and/or the esters thereof exhibit distinct advantages over the compounds known from the literature. The novel tin catalysts according to the invention are particularly suitable as catalysts for condensation-crosslinking polysiloxane compositions for the production of RTV products having distinctly improved storage stability. The novel catalysts are furthermore distinguished by elevated reactivity.
The present invention accordingly provides novel tin catalysts obtainable by the reaction of and
The term organotin compounds a) includes any known prior art compounds.
Preferred organotin compounds a) are mono-, di- and triorganyltin compounds of the general formula (I) cycloalkyl or C.sub.6 -C.sub.14 aryl residues and --NHR.sup.1, --OSiR.sup.1.sub.3, --OSi(OR).sup.1.sub.3 and/or compounds of the general formula R.sup.1.sub.2 SnX', R.sup.1.sub.3 SnX'.sub.1/2 and/or R.sup.1 SnX'.sub.3/2 where X'=O, S.
The hydrogen atoms of the linear or branched C.sub.1 -C.sub.30 alkyl, C.sub.5 -C.sub.14 cycloalkyl or C.sub.6 -C.sub.14 aryl residues may here also be substituted by halogen atoms, OH, NH.sub.2, NO.sub.2 or C.sub.1 -C.sub.6 alkyl residues.
In the event that the residues X, X' and R.sup.1 occur more than once in the molecule, they may be identical or different.
Particularly preferred compounds are dioctyltin oxide, dibutyltin oxide, dimethyltin dichloride, dibutyltin dichloride, tributyltin chloride, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin maleate, dibutyltin dihexoate, dibutyltin dioctoate, dioctyltin dioctoate, dioctyltin dilaurate, dioctyldibutoxystannane and/or tributylethoxystannane.
For the purposes of the invention, monoorthophosphoric acid esters and/or orthophosphoric acid b) preferably comprise orthophosphoric acid and/or the esters thereof of the following formula (II) -C.sub.30 alkenyl or alko
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Friebe Robert
Sattlegger Hans
Sockel Karl-Heinz
Weber Wilhelm
Wilms Axel
GE Bayer Silicones GmbH & Co. KG
Wood Elizabeth D.
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