Methacrylic polymer material with improved fire resistance
Light-scattering methacrylic polymer material comprising: from 80 to 90% of a methacrylic (co)polymer; from 5 to 15% of a compatible fire retardant chosen from a halogenated polyphosphonate and a halogenated neutral ester compound of phosphoric acid; and from 1 to 5% of a silica having an elementary particle size of less than 500 nm.
1 . Light-scattering methacrylic polymer material comprising:
from 80 to 90 percent by weight of a methacrylic (co)polymer containing predominantly methyl methacrylate units;
from 5 to 15 percent by weight of a fire retardant compatible with the methyl methacrylate monomer and the methacrylic (co)polymer, the said fire retardant being chosen from a halogenated polyphosphonate compound, a halogenated neutral ester compound of phosphoric acid or a mixture of these two compounds; and
from 1 to 5 percent by weight of silica having an elementary particle size of less than 500 nm.
2 . The polymer material of claim 1 wherein said silica has an elementary particle size of less than 100 nm.
3 . The polymer material according to claim 1 , characterized in that the methacrylic (co)polymer employed is a methyl methacrylate homopolymer.
4 . The polymer material according to claim 1 , characterized in that the halogenated polyphosphonate compound used is a chlorinated polyphosphonate.
5 . The polymer material according to claim 1 , characterized in that the halogenated neutral ester of phosphoric acid is tris(2-chloroisopropyl) phosphate.
6 . The polymer material according to claim 1 , characterized in that the silica is a precipitated silica.
7 . The polymer material according to claim 1 , characterized in that the silica has an elementary particle size of less than 15 nm.
8 . The polymer material according to claim 7 , characterized in that the silica has an elementary particle size of less than 10 nm.
9 . The polymer material according to claim 1 , characterized in that it comprises:
from 82 to 86 percent by weight of the methacrylic (co)polymer;
from 10 to 12 percent by weight of the fire retardant; and
from 2 to 4 percent by weight of precipitated silica.
10 . The polymer material according to claim 9 characterized in that it comprises:
from 82 to 86 percent by weight of the methacrylic (co)polymer;
from 10 to 12 percent by weight of TCIP;
from 2 to 4 percent by weight of silica RP 635.
11 . The polymer material according to claim 1 , characterized in that it is in the form of sheets.
12 . The polymer material according to claim 11 , characterized in that the sheets have a thickness of between 2.5 and 8 mm.
13 . The polymer material according to claim 12 , characterized in that the sheets have a thickness of between 3 and 6 mm.