Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From silicon reactant having at least one...
Reexamination Certificate
1999-11-17
2001-05-22
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...
C528S016000, C528S033000, C528S043000, C528S014000, C525S106000, C556S462000
Reexamination Certificate
active
06235863
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to the production of saturated siloxane polymers which are made from aromatic siloxane monomers and/or other aromatic monomers. More particularly, this invention relates to the hydrogenation of aromatic siloxane monomers and to the hydrogenation of aromatic polysiloxane copolymers.
BACKGROUND OF THE INVENTION
Linear block copolymers of polystyrene and polydimethylsiloxane have been synthesized, both by graft and block copolymerization. In block copolymerization of such linear polymers, polystyrene (PS) is produced by anionic polymerization with an organo lithium initiator and the living polymer (PS-Li+) created thereby is reacted with hexamethylcyclotrisiloxane, (Me
2
SiO)
3
, in the presence of a polar promoter wherein a block of polydimethylsiloxane (PDMS) grows on the end of the living vinyl aromatic hydrocarbon polymer block.
Typically, saturated versions of unsaturated polymers are obtained by hydrogenation of the product polymer. This often leads to slow kinetics, high viscosities, polymer degradation, etc. It would be highly advantageous to have a method for producing saturated versions of unsaturated polymers which do not require the hydrogenation of the product polymer itself. In one embodiment of the present invention, such a method is provided.
Hydrogenation of aromatic components of polymers is known to be difficult. In fact, in the case of block copolymers of polystyrenes and polydienes, it is well known that the polydienes can be almost completely hydrogenated without affecting the polystyrene significantly. Polystyrene/polysiloxane block copolymers are known, including polysiloxane blocks which contain aromatic functionality. Saturated versions of such polymers cannot be made by conventional polymerization techniques. The present invention provides a method for producing saturated polymers from these polysiloxane copolymers.
SUMMARY OF THE INVENTION
In one embodiment, the present invention provides a method of producing a saturated siloxane copolymer which comprises:
(a) hydrogenating an aromatic siloxane monomer by contacting it with hydrogen in a temperature of 100° C. to 200° C. and a hydrogen pressure of 1000 to 2000 psi for 1 to 6 hours in the presence of a hydrogenation catalyst, preferably a nickel carboxylate/aluminum trialkyl catalyst having an aluminum:nickel ratio of 1:1 to 5:1; and
(b) anionically polymerizing the hydrogenated monomer and, optionally, a non-aromatic siloxane monomer; and
(c) optionally, anionically polymerizing at least one other anionically polymerizable monomer into the saturated siloxane copolymer.
In the second embodiment of the present invention, a method is provided for producing a saturated siloxane polymer which comprises:
(a) optionally, anionically polymerizing at least one anionically polymerizable monomer to form a polymer block; and
(b) anionically polymerizing an aromatic siloxane monomer and, optionally, a non-aromatic siloxane monomer, on the end of the optional polymer block of (a); and
(c) hydrogenating the siloxane polymer by contacting it with hydrogen at a temperature of 100° C. to 200° C. and a hydrogen pressure of 1000 to 2000 psi for 1 to 6 hours in the presence of a hydrogenation catalyst, preferably a nickel carboxylate/aluminum trialkyl catalyst having an aluminum:nickel ratio of 1:1 to 5:1.
REFERENCES:
patent: 4956484 (1990-09-01), Gementi et al.
patent: 4977291 (1990-12-01), Gementi et al.
patent: 4997898 (1991-03-01), Ishihara et al.
patent: 5670688 (1997-09-01), Dinh et al.
Haas Donald F.
Moore Margaret G.
Shell Oil Company
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