Distillation: processes – separatory – Addition of material to distilland to inhibit or prevent...
Reexamination Certificate
2001-08-08
2002-11-05
McKane, Joseph K. (Department: 1626)
Distillation: processes, separatory
Addition of material to distilland to inhibit or prevent...
C203S007000, C203S065000, C544S170000, C556S401000, C558S194000
Reexamination Certificate
active
06475347
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to polymerization inhibitors for use in the stabilization of polymerizable monomers, compositions containing them, and their preparation. More particularly, this invention is directed to the use of these inhibitors as stabilizers during the production and subsequent storage of acryloxysilanes and methacryloxysilanes.
2. Description of Related Art
Acryloxysilanes and methacryloxysilanes are chemically reactive materials that are useful in many commercial applications. For example, such compounds are useful as coupling agents to bond organic compounds to inorganic materials. In particular, 3-methacryloxypropyltrimethoxysilane is widely used as a coupling agent in enhancing the performance of fiberglass-reinforced products.
U.S. Pat. No. 3,258,477 discloses silanes characterized by a trifunctional silicon atom at one end of the molecule and an acryloxy group on the other end of the molecule and to aqueous solutions formed therefrom.
U.S. Pat. No. 3,305,483 discloses a method of preparation and compositions of a variety of hindered phenolic benzylamines, which are antioxidants, wherein the linkage between benzylic nitrogen and aromatic rings is limited to a methylene group.
U.S. Pat. No. 4,709,067 discloses a process for preparing, purifying and/or storing methacryloxy or acryloxy containing organosilicon compounds without the undesirable polymerization normally associated with the methacrylate bonds. In an alternative embodiment, the process includes the addition of certain stabilizers, and in particular diketone or ketoester stabilizers.
U.S. Pat. No. 4,780,555 discloses a method for preparing acryl-functional halosilanes by reacting a halosilane with an acryloxy or methacryloxy-functional organic compound in the presence of a platinum hydrosilation catalyst and a stabilizing amount of phenothiazine, wherein the reaction mixture is contacted with an oxygen-containing inert gas. A method for stabilizing the above reaction mixture by contacting it with the oxygen-containing gas is also disclosed.
U.S. Pat. No. 5,103,032 discloses compositions containing an acryloxysilane or a methacryloxysilane and an N,N-dialkylaminomethylene phenol in an amount at least sufficient to inhibit polymerization of the silane during its formation, purification, and storage. Methods for producing such compositions are also provided.
U.S. Pat. No. 5,145,979 discloses processes for the preparation of &ggr;-methacryloxypropylsilane compounds which comprise carrying out the reaction of allyl methacrylate with a hydrosilane compound in the presence of a platinum catalyst, while allowing at least one of a hindered phenol compound and an aromatic amine compound to coexist in the reaction system with an alkylamine compound or an amide compound, or with a gas containing molecular oxygen, or with a phenol compound having an aminoalkylene group. By using these processes as provided, gelation of the reaction mixture in the reaction system and during the course of purification thereof by distillation is said to be effectively avoided and the desired &ggr;-methacryloxypropylsilane compounds obtained in good yield.
U.S. Pat. No. 5,616,753 discloses a method for inhibiting the polymerization of unsaturated silanes by the addition of a non-aromatic stable free radical during any of the steps of the formation of the desired silane, the purification of the desired silane, and to the desired silanes, as well as compositions of the inhibitors and the silanes. Particular classes of silanes to be inhibited include acryloxy-, methacryloxy-, and vinyl-functional silanes. The free radicals for use as inhibitors include various nitroxides. The free radicals are effective as inhibitors at elevated temperatures, for extended periods of time, and even in the absence of molecular oxygen.
U.S. Pat. No. 5,616,774 and commonly assigned E. P. No. 744,392 disclose hindered phenolic benzylamines wherein the methylene linkages between benzylic nitrogen and aromatic rings are substituted with aromatic or otherwise multiply bonded carbon groups or heteroatom groups, wherein said amines are isolated or non-isolated intermediates leading to the ultimate preparation of stable hindered quinone methides.
U.S. Pat. No. 5,723,643 discloses a method to make high-purity acryloxy- or methacryloxy-functional organosilicon compounds in high yields by inhibiting gelation of the reaction product during preparation. The method comprises (A) reacting an acrylate or methacrylate ester of an alcohol comprising an aliphatically unsaturated bond or a phenol comprising an aliphatically unsaturated bond with a (B) SiH-functional silicon compound in the presence of (C) a hydrosilylation reaction catalyst and (D) a polymerization inhibitor described by a given formula. The method can further comprise distillation of the reaction mixture resulting from the reaction of component (A) and (B) in the presence of component (D).
U.S. Pat. No. 5,914,418 discloses a method for inhibiting polymerization of acrylic-functional silanes comprising forming a mixture comprising an acrylic-functional silane and a polymerization inhibitor described by a given formula.
The disclosures of the foregoing are incorporated herein by reference in their entirety.
SUMMARY OF THE INVENTION
This invention relates to the composition and method of preparation of polymerization inhibitors and compositions containing them for use in the stabilization of polymerizable monomers. Furthermore, this invention encompasses the use of these inhibitors as stabilizers during the production and storage of acryloxysilanes and methacryloxysilanes. (For convenience, the term “(meth)acryloxysilanes” will be used hereinafter to refer to both acryloxysilanes and methacryloxysilanes.) The inhibitors described herein and potential degradation products thereof can be easily removed from the (meth)acryloxysilane monomers by distillation, thus allowing for them to be easily substituted by a second polymerization inhibitor with more desirable physical properties.
More specifically, the present invention is directed to a compound of the structure
wherein
R
1
, R
2
, and R
3
are organic radicals of C
1
to C
20
, such that the combination of the three contain at least twelve carbon atoms and R
3
is bound to the methylene carbon atom between X and the aromatic ring by at least one saturated carbon atom, allowing it to be easily separated from the polymerizable monomer by distillation;
R
1
and R
2
have sufficient steric bulk to protect the phenol from reacting with an alkoxy group or halogen bound to silicon; and
X is a neutral heteroatomic radical of oxygen, nitrogen, or phosphorus.
In another aspect, the present invention is directed to a composition comprising a (meth)acryloxysilane and a stabilizing amount of at least one compound of the structure
wherein
R
1
, R
2
, and R
3
are organic radicals of C
1
to C
20
, such that the combination of the three contain at least twelve carbon atoms and R
3
is bound to the methylene carbon atom between X and the aromatic ring by at least one saturated carbon atom, allowing it to be easily separated from the polymerizable monomer by distillation;
R
1
and R
2
have sufficient steric bulk to protect the phenol from reacting with an alkoxy group or halogen bound to silicon; and
X is a neutral heteroatomic radical of oxygen, nitrogen, or phosphorus.
In still another aspect, the present invention is directed to a method for the stabilization of (meth)acryloxysilanes during their production, storage, or both comprising adding thereto a compound of the structure
wherein
R
1
, R
2
, and R
3
are organic radicals of C
1
to C
20
, such that the combination of the three contain at least twelve carbon atoms and R
3
is bound to the methylene carbon atom between X and the aromatic ring by at least one saturated carbon atom, allowing it to be easily separated from the polymerizable monomer by distillation;
R
1
and R
2
have sufficient steric bulk to protect the phenol from reacting with an alkoxy group or
Hartman Kenneth W.
Sheridan Robert E.
Crompton Corporation
Dilworth Michael P.
Saeed Kamal
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