Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2000-02-23
2002-03-19
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C528S027000, C528S029000, C549S215000, C556S451000, C556S462000, C556S454000
Reexamination Certificate
active
06359097
ABSTRACT:
The field of the present invention is that of polyorganosiloxanes containing one or a number of functionalities introduced by substituents of the silicon and conferring specific properties on the polymers, for example antiadhesive, lubricating or compatibilizing properties and the like, which are much sought after in silicone applications.
More precisely, the present invention relates to a multifunctionalized polyorganosiloxane in which the functionalities are each carried by different siloxy units, via an SiC or SiOC bond.
The present invention also relates to a process for the functionalization of polyorganosiloxanes which makes it possible, in particular, to result in the multifunctionalized polyorganosiloxanes targeted above.
The functionalization of the polyorganosiloxanes can conventionally be carried out by substitution of the hydrogens carried by the silicon atoms of the chain.
According to a first route, this substitution can consist of a hydrosilylation reaction between a polyorganohydrosiloxane and an olefinic reagent carrying at least one &pgr; double bond capable of reacting with the hydrogen according to an addition mechanism. Hydrosilylation is a reaction which is fully known in the technical field under consideration. This reaction is usually catalysed with platinum. It is widely described in the literature. In this respect, reference may be made, for example, to the article by V. M. Kopilov et al., Z. Obsh. Khim., vol. 57 (5), (1987) p. 1117-1127. In this first route, all the silicon atoms containing available hydrogen are substituted by organic units via SiC bonds, the said organic units being introduced by the olefinic reactant(s). One illustration, among others, of hydrosilylation is given in European Patent Application No. 504,800, which describes the addition of a polyoxyalkylene substituted by an olefinic group (vinyl) to a polydimethylhydrosiloxane of formula:
Me
3
SiO—(Me
2
SiO)
157
—(MeHSiO)
21
—SiMe
3
(Me═CH
3
),
in the presence of a monocarboxylic ester of a solvent of the alkanediol type. In this case, it clearly seems that a single type of functionalization can be envisaged and only the groups capable of being substituted by olefinic residues can be grafted onto the polyorganosiloxane.
A second functionalization route is that according to which the silicons of the polyorganosiloxane concerned are substituted by functional residues bonded to the polyorganosiloxane by virtue of SiOC bridges. The reactions which can be envisaged for doing this are, for example, those involving &agr;,&ohgr;-chlorosiloxanes and alcohols or alternatively polyorganohydrosiloxanes and alcohols according to a dehydrogenation/condensation mechanism.
These dehydrogenation/condensation reactions, also described as alcoholyses of organohydropolysiloxanes, are described in particular in S. Koama and Y. Humeki, Journal of Applied Polymer Science, Vol.21 (277), pages 863-867.
This article refers to polymethylhydrosiloxanes brought into contact with an alcohol of the methanol or ethanol type and of a catalyst chosen from bases and certain metal chlorides (Lewis acids). The solvent employed is benzene. The writers thus obtain a polyalkoxymethylsiloxane which itself also has only one functionality.
Record has also been had to dehydrogenation/condensation in the invention described by U.S. Pat. No. 5,310,842 relating to alkoxy-substituted polyorganosiloxanes. These products comprise dimethylsiloxy and methylalkoxysiloxy units and contain from 4 to 30 carbon atoms. The catalyst employed in this dehydrogenation/condensation is platinum-containing in nature (chloroplatinic acid). All the starting methylhydrosiloxy functionalities are converted (degree of conversion greater 99%) to alkoxy-substituted units. The alkoxylated side chains are involved in the compatibilization of the polyorganosiloxanes with other products such as, for example, organic polymers, with which they are used in the final applications. Although the writers maintain that these alkoxylated polyorganosiloxanes have good resistance to hydrolysis, it may be permitted to doubt this, taking into account the not insignificant sensitivity of the oxygen bridge in this respect. In addition, this prior invention retains the disadvantage of the monofunctionalization of the polyorganosiloxane.
This review of the prior art makes it appear that multifunctionalized polyorganosiloxanes are lacking. Such products would nevertheless be highly appreciable in certain uses of silicones, because it is obvious that the multifunctionalization only causes an increase in the potentialities of these products which are already very wide-ranging. The introduction of multiple functionalities by grafting would also provide the undeniable advantage of making it possible to construct silicones to measure, specifically suited to the targeted applications.
In the light of this irrefutable fact, one of the essential objects of the present invention is to provide a functionalized polyorganosiloxane, in particular a multifunctionalized polyorganosiloxane, and more particularly still a polyorganosiloxane comprising at least two siloxy sites (or units) of different functionalization, each carrying one type of functionality, corresponding to a plurality of functional types.
Another essential object of the invention is to provide a polyorganosiloxane which can be obtained simply and economically.
Another object of the present invention is to provide a monofunctionalized precursor which makes it possible to gain access to multi-, and in particular bifunctionalized, polyorganosiloxanes.
Another essential object of the invention is to provide a process for the preparation of polyorganosiloxanes having simultaneously a number of types of functional groups introduced by grafting, in particular two types of functional groups, it being necessary for the said process to be easy to implement and with a low cost price, both as regards the raw materials employed and as regards the equipment, energy and time required.
Another essential object of the invention is to provide a process for the synthesis of a precursor or of an intermediate product which makes it possible to result in the multifunctional, in particular bifunctional, polyorganosiloxanes targeted above.
In seeking to meet these objectives, the Applicant Company has discovered in an entirely surprising and unexpected way, after many studies and experiments, that, in contrast to what is taught by Koama and Humeki, the alcoholysis of polymethylhydrosiloxanes results, under certain conditions, in alkoxy-substituted siloxy units and in hydrosiloxy units in which the hydrogen has not reacted, according to a specific stoichiometry.
It follows that the present invention, which makes it possible to achieve the abovesaid objectives among others, relates, as new product per se, to a functionalized polyorganosiloxane, and more particularly a multifunctionalized polyorganosiloxane, comprising, per molecule,
&agr;—on the one hand, at least one functional siloxy unit of formula:
(
R
)
a
YSi
(
O
)
3
-
a
2
(
I
)
in which
a=0, 1 or 2
R is a monovalent hydrocarbon radical chosen from linear or branched alkyls having from 1 to 6 atoms, in particular methyl, ethyl, propyl or butyl, and/or from aryls and in particular phenyl, methyl being more particularly preferred, the R radicals being identical or different when a=2,
Y is a linear or branched alkoxy radical preferably chosen from C
1
-C
15
alkoxys, in particular C
1
-C
6
alkoxys, methoxy, ethoxy and (iso)propoxy being more particularly used,
&bgr;—and, on the other hand, at least one functional siloxy unit of formula:
(
R
)
b
WSi
(
O
)
3
-
b
2
(
II
)
in which
b=0, 1 or 2,
R corresponds to the same definition as that given above for the R substituent of the unit (I) and can be identical to or different from the latter,
W is hydrogen or a monovalent hydrocarbon radical having from 2 to 30 carbon atoms and optionally S and/or O and/or halogen atoms and constituting a functional residue, bonded to the silicon via an Si—
Jost Philippe
Peignier Michel
Priou Christian
Lu Caixia
Rhodia Chimie
Wu David W.
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