Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
2001-04-12
2003-04-08
Moore, Margaret G. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From silicon reactant having at least one...
C502S185000, C528S015000, C528S019000, C528S032000, C556S451000, C585S435000, C549S512000
Reexamination Certificate
active
06545115
ABSTRACT:
The present invention relates to a novel process for preparing a stable silicone oil containing ≡SiH groups and hydrosilylable functions. In particular, the invention relates to a process of hydrosilylation between silicone oils containing ≡SiH groups and monomers with two hydrosilylable units.
Reactions of silicone oils containing ≡SiH groups with olefins or acetylenic hydrocarbons are very well known. The silicone oils are, for example, of the formulae:
—Me
3
SiO—(MeHSiO)
n
—(Me
2
SiO)
m
—SiMe
3
in which n and m are integers or fractions such that 1≦n≦1000 and 0≦m≦1000;
—Me
2
HSiO—(MeHSiO)
o
—(Me
2
SiO)
p
—SiHMe
2
in which o and p are integers or fractions such that 0≦o≦1000 and 0≦p≦1000.
Many monomers can functionalize silicone oils; for example, alkenes, styrenes, allyl alcohols, allyloxy ethers or allylamines are used as monomers.
These reactions are very commonly used for the synthesis of functionalized silicone oils starting with silicone oils containing ≡SiH groups, which, during the hydrosilylation reaction, are functionalized by the monomers. The oils obtained, containing virtually no ≡SiH units, have applications in very wide fields such as anti-adhesion and lubrication.
In particular, functionalized oils can be prepared with 1,2-epoxy-4-vinylcyclohexane monomers. By way of application, these functionalized silicone oils are then thermally crosslinked in the presence of an acid catalyst such as hydrochloric acid or sulphuric acid, or photochemically crosslinked in the presence, for example, of a cationic photo-initiator for the preparation of anti-adhesive films for paper and/or plastics.
A very large number of catalytic compositions is used in hydrosilylation reactions. The catalytic compositions most widely known contain metals such as platinum, rhodium, cobalt or palladium. Specific examples of such catalytic compositions are platinum halides and rhodium halides, for example H
2
PtCl
6
, PtCl
2
, (RhCl
3
.H
2
O), complexes of platinum with siloxanes containing unsaturated groups, complexes of platinum with olefins and cationic complexes of platinum with nitrites as ligands.
Generally, the catalytic compositions used in the hydrosilylation reaction are homogeneous catalytic compositions, i.e. the said compositions are dissolved in the reaction medium. One of the compositions most widely used is the catalytic Karstedt composition described in particular in U.S. Pat. No. 3,775,452.
However, during the hydrosilylation reaction according to processes of the prior art, isomerization reactions of the unsaturated monomers are observed to different degrees, which makes it necessary to work with a molar excess of monomer relative to the silicone oil in the reaction medium.
Moreover, when it is desired to prepare silicone oils comprising both ≡SiH groups and hydrosilylable functions in the structure, the processes of the prior art are inapplicable and unsuitable; the silicone oils obtained are not stable to allow their subsequent use. In particular, during the devolatilization step, the hydrosilylable functions grafted onto the silicone oil structure have a tendency to react together, as in the case of the totally functionalized silicone oils, and/or with the ≡SiH groups of the silicone oil obtained; this gives rise to uncontrolled polymerization and crosslinking reactions and is reflected in the formation of gum and/or resin. These reactions can be initiated in particular by the presence of a trace of the usual catalytic compositions, such as homogeneous catalytic compositions.
In addition, the functionalized silicone oils obtained from processes using homogeneous catalysis are generally colored, from about 80 to about 300 Hazen; consequently, this limits the fields in which it can be envisaged to use them, in particular in transparent and anti-adhesive films for paper or for transparent films (for example of polyester type). In these cases, the silicone oil requires additional purification steps in order to be usable after crosslinking, in transparent films; these additional steps make the industrial implementation expensive and thus economically relatively non-viable.
The Applicant has developed a novel process for preparing a stable silicone oil, containing both ≡SiH groups and hydrosilylable functions, and which allows the drawbacks mentioned above to be reduced significantly, in particular the uncontrolled reactions during the devolatilization step.
This novel process for preparing a stable silicone oil containing ≡SiH groups and hydrosilylable functions is carried out using a first silicone oil containing ≡SiH groups and monomers with two hydrosilylable units.
The silicone oils obtained from the process according to the invention comprise both ≡SiH groups and hydrosilylable functions and are stable during the devolatilization step and stable on storage; this makes it possible subsequently to use the silicone oils according to the invention in applications which require both the presence of ≡SiH groups and hydrosilylable monomers.
In addition, the process according to the invention makes it possible to obtain colorless and transparent oils, with a very low coloration from about 3 to about 100 Hazen, without requiring decolorization and/or purification steps which are relatively non-viable economically and industrially. Needless to say, it is necessary, for this purpose, for the starting monomers to be colorless and transparent.
In particular, the silicone oils obtained from the process of the invention can be used, after crosslinking, in transparent and anti-adhesive films and coatings for papers, for glasses and for plastics.
This novel process for preparing a stable silicone oil containing ≡SiH groups and hydrosilylable functions from a starting oil, referred to as the first silicone oil, containing ≡SiH groups and monomers with two hydrosilylable units, comprises the following steps:
(a) an amount of from 5 to 5000 ppm, preferably from 10 to 100 ppm, of heterogeneous catalytic composition relative to the total mass of the reagents is introduced into the reaction medium;
(b) the first silicone oil is introduced into the reaction medium;
(c) the said reaction medium is heated to a temperature of between 25° C. and 200° C. and preferably between 50° C. and 160° C.;
(d) the monomers are then introduced over a period of between 0 and 24 h, preferably between 2.5 and 5 h; the monomer/≡SiH molar ratio of the said oil is between 0.0001 and 1;
(e) the silicone oil obtained containing ≡SiH groups and hydrosilylable functions is then separated from the heterogeneous catalytic composition, for example by filtration; and
(f) the silicone oil containing ≡SiH groups and hydrosilylable functions is finally devolatilized.
The separation step (e) makes it possible, where appropriate, to remove all trace of turbidity from the functionalized silicone oil obtained. Moreover, the heterogeneous catalytic composition can be recovered and then reused, without the need for regeneration, with or without washing, and without any appreciable reduction in its performance characteristics being detected. As regards the devolatilization (f), the stability of the silicone oils is not affected during this step.
Furthermore, the process according to the invention can advantageously be carried out in bulk, which means that the reaction between the silicone oil and the monomer(s) is carried out in the absence of solvent. However, many solvents such as toluene, xylene, octamethyltetrasiloxane, cyclohexane or hexane can be used.
Virtually any type of monomer containing two hydrosilylable units can be used in the present process. Furthermore, the monomers used can be identical and/or different. However, preferably, at least one of the hydrosilylable units of the monomers is a vinyl or allylic unit.
The best results for the preparation of silicone oils, in accordance with the spirit of the invention, were obtained with monomers having the formulae:
in which:
the symbols R
1
and
Breunig Stefan
Mignani Gerard
Moore Margaret G.
Peng Kuo-Liang
Rhodia Chimie
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