Compositions of expandable vinyl aromatic polymers with an improved thermal insulation capacity, process for their preparation and expanded articles obtained therefrom
Expandable vinyl aromatic polymers which comprise: a matrix obtained by polymerizing 50-100% by weight of one or more vinyl aromatic monomers and 0-50% by weight of at least one copolymer izable monomer; 1-10% by weight, calculated with respect to the polymer (a), of an expanding agent englobed in the polymeric matrix; 0.05-25% by weight, calculated with respect to the polymer (a), of a filler comprising coke with a surface area, measured according to ASTM D-3037/89, ranging from 5 to 50 m 2 /g.
1. A composition, comprising an expandable vinyl aromatic polymer comprising:
(a) a polymeric matrix (a) obtained by polymerizing a base comprising 50-100% by weight of at least one vinyl aromatic monomer and 0-50% by weight of at least one co-polymerizable monomer;
(b) 1-10% by weight, calculated with respect to the polymeric matrix (a), of an expandable agent (b) englobed in the polymeric matrix (a); and
(c) 1-8% by weight, calculated with respect to the polymeric matrix (a), of at least one coke selected from the group consisting of a needle coke and a calcined coke, in particle form with an average diameter of particles ranging from 0.5 to 100 μm and with a surface area, measured according to ASTM D-3037/89 (BET), ranging from 5 to 50 m 2 /g;
said at least one coke being homogeneously dispersed in the polymeric matrix (a); and
wherein expanded articles derived from said composition have a density ranging from 5 to 50 g/l and a thermal conductivity more than 10% lower than the same expanded articles without added athermanous filler.
2. The composition according to claim 1 , further comprising:
from 0.1 to 8% by weight, with respect to the polymeric matrix (a), of a self-extinguishing brominated additive (d) comprising at least 30% by weight of bromine and 0.05 to 2% by weight, with respect to the polymeric matrix (a), of a synergic product comprising at least one labile C—C or O—O bond.
3. An expanded article having a density ranging from 5 to 50 g/l and a thermal conductivity ranging from 25 to 35 mW/mK, said article obtained from an expandable vinyl aromatic polymer comprising:
(a) a polymeric matrix (a) obtained by polymerizing a base comprising 50-100% by weight of at least one vinyl aromatic monomer and 0-50% by weight of at least one co-polymerizable monomer;
(b) 1-10% by weight, calculated with respect to the polymeric matrix (a), of an expandable agent (b) englobed in the polymeric matrix (a); and
(c) 1-8% by weight, calculated with respect to the polymeric matrix (a), of at least one coke selected from the group consisting of a needle coke and a calcined coke, in particle form with an average diameter of particles ranging from 0.5 to 100 μm and with a surface area, measured according to ASTM D-3037/89 (BET), ranging from 5 to 50 m 2 /g;
said at least one coke being homogeneously dispersed in the polymeric matrix (a),
wherein said expanded article has a thermal conductivity more than 10% lower than the same expanded article without added athermanous filler.
4. The composition according to claim 1 , wherein the expandable vinyl aromatic polymer is in the form of granules having a surface comprising at least one of an ionic surface active agent and a non-ionic surface active agent that comprises a condensate of ethylene oxide and propylene oxide.
5. The expanded article according to claim 3 , wherein the expandable vinyl aromatic polymer is in the form of granules having a surface comprising at least one of an ionic and a non-ionic surface active agent that comprises a condensate of ethylene oxide and propylene oxide.
6. The composition of claim 1 , which is in the form of granules, wherein the coke is homogenously dispersed in the granules.
7. The expanded article of claim 3 , wherein the expandable vinyl aromatic polymer is in the form of granules, wherein the coke is homogenously dispersed in the granules.
8. The composition according to claim 1 , wherein the coke has a surface area of from 5 to 20 m 2 /g.
9. The expanded article according to claim 3 , wherein the coke has a surface area of from 5 to 20 m 2 /g.
10. The composition according to claim 1 , which does not comprise graphite.
11. The expanded article according to claim 3 , which does not comprise graphite.
12. The composition according to claim 1 , comprising 4-8% by weight of the coke.
13. The expanded article according to claim 3 , comprising 4-8% by weight of the coke.
14. The composition according to claim 1 , in the form of thermally expandable pellets, wherein the coke is dispersed homogeneously in the pellets.
15. The composition according to claim 1 , wherein expanded articles derived from said composition have a density ranging from 10 to 25 g/l and a thermal conductivity ranging from 25 to 35 mW/mK.
16. The composition according to claim 1 , wherein extruded articles obtained from said composition have a density ranging from 20 to 40 g/l and a thermal conductivity ranging from 25 to 35 mW/mK.
17. The expanded article according to claim 3 , having a density ranging from 20 to 40 g/l.
18. The expanded article according to claim 3 , having a density ranging from 10 to 25 g/l.
19. The composition according to claim 1 , wherein expanded articles obtained from said composition have a density from 10 to 25 g/l and a thermal conductivity ranging from 30.5 to 35 mW/mK.
20. The expanded article according to claim 3 , having a density ranging from 10 to 25 g/l and a thermal conductivity ranging from 30.5 to 35 mW/mK.
21. A composition, comprising an expandable vinyl aromatic polymer comprising:
(a) a polymeric matrix (a) obtained by polymerizing a base comprising at least one vinyl aromatic monomer selected from the group consisting of styrene and α-methylstyrene;
(b) 1-10% by weight, calculated with respect to the polymeric matrix (a), of an expandable agent (b) englobed in the polymeric matrix (a); and
(c) 1-8% by weight, calculated with respect to the polymeric matrix (a), of at least one coke selected from the group consisting of a needle coke and a calcined coke, in particle form with an average diameter of particles ranging from 0.5 to 100 μm and with a surface area, measured according to ASTM D-3037/89 (BET), ranging from 5 to 50 m 2 /g;
said at least one coke being homogeneously dispersed in the polymeric matrix (a); and
wherein expanded articles derived from said composition have a density ranging from 5 to 50 g/l and a thermal conductivity ranging from 25 to 35 mW/mK.
22. The composition according to claim 21 , further comprising:
from 0.1 to 8% by weight, with respect to the polymeric matrix (a), of a self-extinguishing brominated additive (d) comprising at least 30% by weight of bromine and 0.05 to 2% by weight, with respect to the polymeric matrix (a), of a synergic product comprising at least one labile C—C or O—O bond.
23. An expanded article having a density ranging from 5 to 50 g/l and a thermal conductivity ranging from 25 to 35 mW/mK, said article obtained from an expandable vinyl aromatic polymer comprising:
(a) a polymeric matrix (a) obtained by polymerizing a base comprising at least one vinyl aromatic monomer selected from the group consisting of styrene and α-methylstyrene;
(b) 1-10% by weight, calculated with respect to the polymeric matrix (a), of an expandable agent (b) englobed in the polymeric matrix (a); and
(c) 1-8% by weight, calculated with respect to the polymeric matrix (a), of at least one coke selected from the group consisting of a needle coke and a calcined coke, in particle form with an average diameter of particles ranging from 0.5 to 100 μm and with a surface area, measured according to ASTM D-3037/89 (BET), ranging from 5 to 50 m 2 /g;
said at least one coke being homogeneously dispersed in the polymeric matrix (a).