Use of tin derivatives as latent polycondensation catalysts,...

Details Use of tin derivatives as latent polycondensation catalysts,... Use of tin derivatives as latent polycondensation catalysts,...

1996-10-07

2001-02-13

Mulpuri, Savitri (Department: 2812)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Organic compound containing

C502S242000, C502S349000, C502S352000

Reexamination Certificate

active

06187711

ABSTRACT:

The present invention relates to the use of tin derivatives as latent polycondensation catalysts. The invention relates more particularly to the use of tin derivatives having tin-tin bonds.
The use of tin salts as polycondensation catalysts has been known for several decades.
These derivatives are used in particular for the condensation of silicones and for the production of polyurethane.
In the course of the last few years one application has become increasingly prevalent, namely the marketing of premixes which are capable, on the one hand, of being stored for a long time and, on the other hand, of being able to give the desired polymer, or polycondensate, as quickly as possible under the implementation conditions.
These conditions are generally antinomic. For this reason, very few catalysts have been developed in this field.
Accordingly, one of the aims of the present invention is to find tin derivatives which are inert or relatively inactive as catalysts under the storage conditions.
Another aim of the present invention is to find tin compounds of the above type which, when placed under the conditions of implementation of premixes, undergo a conversion to give derivatives which are active under these conditions.
Another aim of the present invention is to provide novel tin derivatives which have the above characteristics.
Another aim of the present invention is to provide tin derivatives which are active as polycondensation catalysts and which are derived from the above derivatives.
Another aim of the present invention is to provide premixes which are capable of giving silicones and polyurethanes which are both inert under the storage conditions and become condensed under the conditions of application.
These aims and others which will appear later are achieved by means of the use of tin derivatives which have at least one tin-tin bond and which have no tin-chalcogen-tin bonding sequences and preferably having no tin-(metalloid of column V, VI, VII)-tin bonding sequences as latent polycondensation catalysts, which can be activated by oxygen. The Periodic Table used corresponds to that published in the Bulletin of the French Chemical Society in its supplement No. 1 dated January 1966.
Indeed, it has been demonstrated, entirely surprisingly, in the course of the study which led to the present invention, that when these derivatives were subjected to the action of oxygen (in particular to that of atmospheric oxygen), they led to derivatives having a high catalytic capacity for polycondensation, and in particular for unmasking, this being despite the fact that the compounds with tin-tin bonding possessed little or no such capacity.
The oxygen may also be provided by oxidation agents bearing oxygen atom(s), such as halogenate (iodate, etc.), peroxide, mixed or non-mixed, of metals (such as oxylith: Na—O—O—Na), of hydrogen and of hydrocarbon radicals, in general of alkyl and/or acyl radicals; it is, however, preferable for the oxygen to be provided in gaseous form (O
2
, or even O
3
) and in particular in atmosphere (air) form.
When they are not cyclic, it is desirable for these derivatives to have at least one single (monovalent) bond of tin-chalcogen(-carbon), advantageously tin-oxygen(-carbon), type.
The compounds with tin-tin bonding advantageously have the general formula (I):
R
1
-Y
n
-R
4
  (I)
where R
1
and R
4
which may
be similar or different and be chosen from hydrogen, advantageously from hydrocarbon radicals, or
together form a divalent radical or a single bond which ensures the formation of a ring:
where n is at least equal to 2:
where the groups Y, which may be similar or different, represent a tin-membered chain unit of structure:
R′ and R″, which may be similar or different, are chosen from hydrogen and, advantageously, hydrocarbon radicals.
When the compounds are cyclic, it is highly preferably for them to be 5-, 6- or 7-membered or a mixture of such rings.
If it is desired to distinguish between the chain units, a representation may be used which uses the
j
row of the chain unit in the sequence, where the
j
s cross from left to right.
j
then takes all the integer values from 1 to n, including the limits:
Thus, by way of exemplary example, when n is equal to 4 and takes all the values from 1 to 4, the formula may develop as follows:
R
j
and R
j′
which may be similar or different, are chosen from hydrogen and, advantageously, hydrocarbon radicals.
R
1
and R
4
are advantageously chosen from aryls, alkyls, alkoxyls, acyloxyls, silyls and silyloxyls, preferably acyloxyls.
R
1
and R
4
may also be chosen from those corresponding to the anions of acids having both a hydrocarbon radical and an oxygen-containing acidic function of inorganic nature. Examples of these families may be sulphonic acids, alkyl monophosphates, alkyl phosphates, and phosphonates and phosphinates which may be partially esterified.
n is advantageously not more than 10, preferably between 2 and 8. n is an integer unless it is desired to give a statistical value of the number of tin-membered chain units for a mixture of various derivatives according to the present invention.
When R
1
and R
4
together constitute a bond which makes it possible to form a cyclic derivative, n is equal to at least 3 and is advantageously chosen between 5 and 7, preferably equal to 6, or corresponds to a mixture of 5- and 6-membered derivatives.
When R′ and R″ are chosen from hydrocarbon radicals, these radicals are advantageously chosen from aryls, alkyls, including aralkyls, silyls, alkoxyls, acyloxyls and silyloxyls.
The choice of radicals depends on the property which it is desired to emphasize. If it is desired to limit the catalytic activity of the starting compound to the maximum or if it is desired to limit the risks of an untimely oxidation to the maximum, it is desirable to have compounds whose radicals are of high steric bulk in order to protect access to the tin.
Thus, it is desirable for at least one of the radicals R
1
and R
4
, and preferably both, to have branching alpha, beta or gamma to the tin.
This branching may be branching corresponding to a tertiary carbon when it is strongly desired to avoid any untimely action during storage of the compound of the present invention.
Branches may also be borne by the radicals R′ and R″. It may be advantageous for only one of the two radicals R′ and R″ to have branching, this being for each of the chain units.
If a lower reactivity is desired relative to that of the derivatives containing alkyl substituents, the alkyl radicals may be replaced by aryl radicals. It should be noted that the bulk of an aryl radical may be increased by substituting at least one of the positions ortho to the carbon-tin bond.
However, in general, it is preferable for the substituents R′ and R″ not to be all aryl radicals, advantageously not more than half.
If, on the other hand, it is desired to increase the reactivity of the compound, it is preferable for at least one of the radicals R
1
or R
4
to be a group attached via a chalcogen, preferably an oxygen, to tin: the groups R
1
and/or R
4
are thus advantageously alkoxyls or equivalents, preferably acyloxyl(s) or equivalents.
In order to avoid weighting down the catalyst precursor molecule, it is preferable to limit the number of carbons to 50 (only one significant figure), preferably to 30 (only one significant figure) carbon atoms per tin atom contained in the molecule.
It is also advantageous for each of the radicals to have not more than 20 (one significant figure), preferably 10 (only one significant figure), carbon atoms.
Among the compounds giving very good results, mention should be made of compounds in which R
1
and advantageously R
4
are acyloxyls advantageously branched on the carbon vicinal or antevicinal to the carbonyl function and in which n is equal to 2; the other radicals advantageously being chosen from aryls and alkyls, preferably with not more than 2 aryls and, more preferably, none.
In the present description, the term al

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