Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
1999-11-22
2001-05-29
Hoke, Veronica P. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S386000, C524S387000, C524S388000, C524S409000, C524S410000
Reexamination Certificate
active
06239219
ABSTRACT:
2. BACKGROUND OF THE INVENTION
2.1 Technical Field
The subject of the present invention is thermoplastic compositions with improved fire resistance and in particular compositions based on polyamide resins and/or on alkenylaromatic (co)polymers. The fire resistance is assessed, on the one hand, by the resistance to combustion or to self-ignition and, on the other hand, by the susceptibility to dripping.
2.2 Background Art
Due to their excellent physical properties, thermoplastic polyamide resins are widely used in many applications in the automobile industry, aeronautics, the electrical field, and the like, but their development has been held back because of their combustibility.
Many solutions have been proposed in the literature for improving the resistance to combustion of polyamide-based thermoplastic compositions.
Halogenated derivatives such as decabromodiphenyl ether, optionally in combination with Sb
2
O
3
, have been added to polyamide resins, but halogenated compounds generate acid halides which are given off during the manufacture and/or during the use of the compositions in which they are incorporated, thus resulting in risks of corrosion of the equipment and pollution of the environment.
Antimony oxide, Sb
2
O
3
is also used in combination with magnesium hydroxide and optionally melamine cyanurate in EP 571,241 for imparting flame-retardancy to thermoplastic polyamide compositions.
It is also known to incorporate phosphorus or its derivatives, such as red phosphorus (U.S. Pat. No. 3,778,407), phosphites or phosphates, but these products are difficult to use and confer an undesirable reddish tinge to polyamide compositions.
Melamine cyanurate improves the resistance to combustion of polyamides but it is not as effective, weight for weight, as some compounds containing a high chlorine or bromine content.
While the aforementioned compounds listed significantly reduce the combustibility of the resins in which they are incorporated, their influence on the susceptibility to dripping is low.
In EP 169,085, a polyol and melamine cyanurate are simultaneously added to polyamide-based compositions, which makes it possible to improve the susceptibility to dripping, but to an extent which is somewhat less than desired.
Alkenylaromatic hydrocarbon polymers and copolymers exhibit poor fire resistance and burn easily.
It is known to add flame-retarding agents to these polymers or copolymers and to the compositions containing them. The most commonly used are compounds containing at least one halogen atom, generally bromine.
It is also known, from JP-A-54/85242, to impart flame-retardancy to polystyrene by means of 3 to 50 parts by weight of melamine cyanurate per 100 parts by weight of polystyrene.
Non-flammable, injection-mouldable thermoplastic compositions comprising at least 60% by weight of melamine and at most 40% by weight of polystyrene are also known from FR-A-2,096,230.
Compositions comprising from 30 to 80 parts by weight of polystyrene, from 20 to 70 parts by weight of melamine and from 0.05 to 5 parts by weight (expressed as phosphorus) of a phosphorus-containing compound are known from JP-A-54/46250.
In EP 438,939, there are described thermoplastic compositions containing at least one alkenylaromatic hydrocarbon (co)polymer, at least one nitrogen-containing compound chosen from melamine and melamine isocyanurate, at least one polyol containing at least 4 hydroxyl functional groups per molecule and, optionally, at least one organic ester of phosphoric acid.
3. SUMMARY OF THE INVENTION
The thermoplastic compositions with improved fire resistance according to the invention, are, in particular, based on polyamide resin(s) or on alkenylaromatic resin(s) and comprise:
antimony oxide Sb
2
O
3
;
melamine cyanurate; and
one or a number of polyols.
These compositions can be used for the preparation of molded, extruded or injected articles, in the form of sheets or films, of composite materials and of powders for coating substrates.
REFERENCES:
patent: 4001177 (1977-01-01), Tsutsumi et al.
patent: 4198493 (1980-04-01), Marciandi et al.
patent: 4317766 (1982-03-01), Kawasaki et al.
patent: 4786673 (1988-11-01), Morival et al.
patent: 5037869 (1991-08-01), Sprenkle
patent: 5185103 (1993-02-01), Eswarakrishan
patent: 5424344 (1995-06-01), Lewin
patent: 6025423 (2000-02-01), Breant
patent: 122697 (1984-10-01), None
patent: 51-571241 (1993-11-01), None
patent: 51-23563 (1976-02-01), None
patent: 51-73047 (1976-06-01), None
Pitts, Janes J.—“Antimony—Halogen Synergy . . .” J. Fire and Flammability—51-58 (1972).
Breant Patrice
Poyet Olivier
Atofina
Hoke Veronica P.
Pennie & Edmonds LLP
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