Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2001-07-24
2003-01-07
Pezzuto, Helen L. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S262000, C526S272000, C526S274000, C526S275000, C526S277000, C526S318400, C526S329200, C526S342000, C526S347000
Reexamination Certificate
active
06503992
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a number of novel phosphorus-containing monomers capable of imparting flame resistant properties to certain high impact polymer compositions synthesized using such monomers.
Polymers derived from a monovinylidene aromatic compound, such as styrene, have successfully been used commercially in numerous end-use applications for a number of years. Such polymers include the high impact modifications thereof in which the impact strength is improved by incorporating a minor amount of a toughening agent, such as a suitable rubber, during the polymerization. One major disadvantage of such polymers is their inherent high flammability. A well-known approach to deal with the flammability has been to incorporate various flame retardant additives to the polymers. A well-known group of such additives are certain halogenated flame retardant organic compounds such as decabromodiphenyloxide.
When such halogenated organic compounds are blended with polymers derived from a monovinylidene aromatic compound, the flammability of the resultant polymer compositions is significantly diminished. However, such halogenated compounds also present potential problems associated with toxicity and environmental impact. To overcome such problems, certain phosphorus-containing compounds such as triphenylphosphate have been used in lieu of halogenated compounds. Despite their proven utility as flame retardant additives for polymers of a monovinylidene aromatic compound, such phosphorus-containing compounds have several known disadvantages. More particularly, such compounds have a tendency to be volatilized and thereby lose their overall effectiveness as flame retardant additives, when polymers blended therewith are being fabricated into useful articles. Such compounds also tend to migrate to the surface of fabricated articles and plate out on the surface of polymer processing equipment in a phenomenon known in the trade as “juicing.” Further, any extra amounts of such compounds used in polymer blends to compensate for the loss of their effectiveness because of the known volatility often tend to plasticize polymer blends thereby adversely impacting certain physical properties thereof such as heat resistance.
Therefore, it remains highly desirable to obtain a monovinylidene aromatic polymer composition having effective flame resistance without disadvantages of previous attempts therefor and related flame retardant additives known in the prior art.
SUMMARY OF THE INVENTION
One aspect of the present invention is a phosphorus-containing compound suitable for use as a comonomer, capable of being copolymerized with monovinylidene aromatic compounds to impart flame resistant properties to the resultant copolymers thereof, comprising compounds of a generic formula:
R
1
is hydrogen or an alkyl;
R
2
is carboalkoxy;
X is oxygen, sulfur or alkylamine;
P is trivalent phosphorus; and
n is 2 or 3.
Another aspect of the present invention is the phosphorus-containing compound of the generic formula above wherein R2 is a radical having a generic formula:
wherein:
R
1
is hydrogen or an alkyl;
X is oxygen, sulfur or alkylamine;
P is trivalent phosphorus; and
n is 2 or 3.
Yet another aspect of the present invention is a phosphorus-containing compound suitable for use as a comonomer, capable of being copolymerized with a monovinylidene aromatic compounds to impart flame resistant properties to the resultant copolymers thereof, comprising compounds of a generic formula:
wherein:
R
1
is hydrogen or an alkyl;
R
2
is carboalkoxy;
X is oxygen, sulfur or alkylamine;
Y is oxygen or sulfur;
P is pentavalent phosphorus; and
n is 2 or 3.
Another aspect of the present invention is the phosphorus-containing compound of the generic formula above wherein R2 is a radical having a generic formula:
wherein:
R
1
is hydrogen or an alkyl;
X is oxygen, sulfur or alkylamine;
Y is oxygen or sulfur;
P is pentavalent phosphorus; and
n is 2 or 3.
Another aspect of the present invention is a flame retardant (co) polymer composition of a monovinylidene aromatic compound a phosphorus-containing compound of the generic formula, which may be toughened or modified with rubber or other elastomers.
DETAILED DESCRIPTION OF INVENTION
Phosphorus-containing monomers of the present invention can generally be categorized as cyclic phosphonite or phosphonate containing esters of fumaric and maleic acid. Synthesis of relevant monomers or compounds of the present invention are well within the capabilities of those skilled in the art.
Examples of useful compounds of the present invention, as identified in accordance with the nomenclature system of Chemical Abstracts, include, without limitation: 2-Butenedioic acid (2E)-, bis[(5,5-dimethyl-1,3,2-dioxaphosphorinan-2-yl)methyl]ester; 2-Butenedioic acid: 2-methyl-, 4-[(5,5-dimethyl-1,3,2-dioxaphosphorinan -2-yl)methyl]1-methyl ester, (2E)-; 2-Propenoic acid, (5,5-dimethyl-2-oxido-1,3,2-dioxaphosphorinan-2-yl)methyl ester; 2-Propenoic acid, 2-methyl -,(4,4,5,5-tetramethyl-1,3,2-dioxaphospholan-2-yl)methyl ester; 2-Propenoic acid, 1-(5,5-dimethyl-2-sulfido-1,3,2-dioxaphosphorinan-2-yl)ethyl ester; and 2-Propenoic acid, (tetrahydro-1,3,5,5-tetramethyl-2-oxido-1,3,2-diazaphosphorin-2(1H)-yl)methyl ester.
Monovinylidene aromatic polymers suitable for use as a matrix in the preparation of the rubber modified monovinylidene aromatic polymer are those produced by polymerizing a vinyl aromatic monomer. Vinyl aromatic monomers include, but are not limited to those described in U.S. Pat. Nos. 4,666,987, 4,572,819 and 4,585,825, which are herein incorporated by reference. Preferably, the monomer is of the formula:
wherein R is hydrogen or methyl, Ar is an aromatic ring structure having from 1 to 3 aromatic rings with or without alkyl, halo, or haloalkyl substitution, wherein any alkyl group contains 1 to 6 carbon atoms and haloalkyl refers to a halo substituted alkyl group. Preferably, Ar is phenyl or alkylphenyl, wherein alkylphenyl refers to an alkyl substituted phenyl group, with phenyl being most preferred. Typical vinyl aromatic monomers which can be used include: styrene, alpha-methylstyrene, all isomers of vinyl toluene, especially paravinyltoluene, all isomers of ethylstyrene, propylstyrene, vinyl biphenyl, vinyl naphthalene, vinyl anthracene and the like, and mixtures thereof. The vinyl aromatic monomers may also be combined with other copolymerizable monomers. Examples of such monomers include, but are not limited to acrylic monomers such as acrylonitrile, methacrylonitrile, methacrylic acid, methyl methacrylate, acrylic acid, and methyl acrylate; maleimide, n-phenylmaleimide, and maleic anhydride. These copolymerizable monomers can be used alone or in combination. For example, a phosphorus-containing compound of the present invention can be copolymerized with a monovinylidene aromatic compound in combination with at least one copolymerizable monomer(s) to produce copolymers of the present invention. A preferred copolymerizable monomer is acrylonitrile. A preferred combination of copolymerizable monomers comprise acrylonitrile and n-phenylmaleimide.
The polymerization of the vinyl aromatic monomer is conducted in the presence of predissolved elastomer to prepare impact modified, or grafted rubber containing products. Rubber modified vinyl aromatic polymers can be prepared by polymerizing the vinyl aromatic monomer in the presence of a predissolved rubber to prepare impact modified, or grafted rubber containing products, examples of which are described in U.S. Pat. Nos. 3,123,655, 3,346,520, 3,639,522, and 4,409,369 which are herein incorporated by reference. The rubber is typically a butadiene or isoprene rubber, preferably polybutadiene. Preferably, the rubber modified vinyl aromatic polymer is high impact polystyrene (HIPS) or acrylonitrile-butadiene-styrene (ABS), with HIPS being most preferred.
The rubber particles typically have a volume average particle size of from 0.2 to 3.0 microns. If a bimodal particle size is produced, the rubber t
Harwood H. James
Mitchell Steven R.
Priddy Duane B.
Stobby William G.
Suh Kyung W.
Pezzuto Helen L.
The Dow Chemical Company
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