EXPANDABLE THERMOPLASTIC NANOCOMPOSITE POLYMERIC COMPOSITIONS WITH AN IMPROVED THERMAL INSULATION CAPACITY

• US 20120264836A1
• Filed: 10/06/2010
• Published: 10/18/2012
• Est. Priority Date: 10/07/2009
• Status: Active Grant

• Current Assignee: Versalis S.P.A, (Eni Petroleum Company Incorporated)
• Original Assignee: Polimeri Europa SPA (Eni Petroleum Company Incorporated)
• Inventors: Felisari, Riccardo, Casalini, Alessandro, Valentino, Olga
• Granted Patent: US 8,969,466 B2
• Time in Patent Office: Days
• US Class Current: 521/79
• CPC Class Codes: C08J 2325/06 Polystyrene
• CPC Class Codes: C08J 9/0066 Use of inorganic compounding ingredients
• CPC Class Codes: C08J 9/0071 Nanosized fillers, i.e. having at least one dimension below 100 nanometers

Abstract

Nanocomposite compositions based on expandable thermoplastic polymers which comprise: a) a polymeric matrix produced by the polymerization of a base comprising one or more polymerizable monomers; b) 1-10% by weight, calculated with respect to the polymer (a), of an expanding agent englobed in the polymeric matrix; c) 0.004-15% by weight, calculated with respect to the polymer (a), of an athermanous filler comprising nano-scaled graphene plates with a thickness (orthogonal to the graphene sheet) not greater than 150 nm, an average dimension (length, width, or diameter) not greater than 10 micrometers and a surface area>50 m2/g.

Claims

1. Nanocomposite compositions based on expandable thermoplastic polymers which comprises:

a) a polymeric matrix produced by polymerization of a base comprising one or more polymerizable monomers;

b) 1-10% by weight, calculated with respect to the polymer (a), of an expanding agent embedded in the polymer matrix;

c) 0.004-15% by weight, calculated with respect to the polymer (a), of an athermanous filler comprising nano-scaled graphene plates with a thickness (orthogonal to the graphene sheet) not greater than 150 nm, an average dimension (length, width, or diameter) not greater than 10 micrometers and a surface area>

50 m²/g.

2. The nanocomposite compositions according to claim 1, wherein the polymerizable monomers are selected from vinyl monomers and vinyl aromatic monomers.

3. The nanocomposite compositions according to claim 2, wherein the polymerizable monomers are selected from vinyl aromatic monomers.

4. The nanocomposite compositions according to any of the previous claims, wherein the athermanous filler comprises up to 6% of graphite and/or carbon coke and/or carbon black, as synergic products.

5. The nanocomposite compositions according to any of the previous claims, wherein the thickness (orthogonal to the graphene sheet) of the nano-scaled graphene plates is less than 50 nm.

6. The nanocomposite compositions according to any of the previous claims, wherein the thickness (orthogonal to the graphene sheet) of the nano-scaled graphene plates ranges from 0.3 to 5 nm.

7. The nanocomposite compositions according to any of the previous claims, wherein the average dimension (length, width, or diameter) of the nano-scaled graphene plates is not greater than 1 micrometer.

8. The nanocomposite compositions according to any of the previous claims, wherein the average dimension (length, width, or diameter) of the nano-scaled graphene plates is not greater than 500 nm.

9. The nanocomposite compositions according to any of the previous claims, wherein the surface area of the nano-scaled graphene plates ranges from 100 to 2,600 m²/g.

10. The nanocomposite compositions according to any of the previous claims, wherein the surface area of the nano-scaled graphene plates ranges from 300 to 2,600 m²/g.

11. Expanded articles obtained with the nanocomposite compositions according to any of the previous claims, having a density ranging from 5 to 50 g/l and a thermal conductivity ranging from 25 to 50 mW/mK.

16. A process for preparing compositions of expandable vinyl aromatic thermoplastic polymers, in beads or granules, according to claims 1 to 10, which comprises polymerizing in aqueous suspension one or more vinyl aromatic monomers, possibly together with at least one polymerizable comonomer in a quantity of up to 50% by weight, in the presence of said athermanous filler comprising said nano-scaled graphene plates with a thickness (orthogonal to the graphene sheet) not greater than 150 nm, an average dimension (length, width, or diameter) not greater than 10 micrometers and a surface area>

50 m²/g and at least in the presence of a peroxide radical initiator system and an expanding agent added before, during or at the end of the polymerization.

17. The process according to claim 16, wherein the athermanous filler comprises in addition to said nano-scaled graphene plates, up to 6% by weight, calculated with respect to the polymer, of said further athermanous additives respectively, such as graphite and/or carbon coke and/or carbon black, as synergic products.

18. The process according to claim 16 or 17, wherein the viscosity of the reagent solution of vinyl aromatic monomers, to be suspended in water, is increased by dissolving vinyl aromatic polymer, in said solution, up to a concentration ranging from 1 to 30% by weight, with respect to the weight of the monomers.

19. The process according to claim 16 or 17, wherein the viscosity of the reagent solution of vinyl aromatic monomers, to be suspended in water, is increased by pre-polymerizing in mass the monomer, or mixture of monomers, until a concentration of polymer ranging from 1 to 30% by weight is obtained.

20. The process according to any of the claims from 16 to 19, wherein, at the end of the polymerization, beads/granules of substantially spherical expandable polymer are obtained, with an average diameter ranging from 0.2 to 2 mm in which said athermanous filler and said possible further athermanous additives are homogeneously dispersed.

21. A process for preparing in mass the compositions of expandable thermoplastic polymers, in granules or beads, according to claims 1 to 10, which comprises the following steps in series:

i. mixing a thermoplastic polymer in granules/pellets or in powder form or already in the molten state, having an average molecular weight MW ranging from 50,000 to 300,000, with said athermanous filler comprising said nano-scaled graphene plates with a thickness (orthogonal to the graphene sheet) not greater than 150 nm, an average dimension (length, width, or diameter) not greater than 10 micrometers and a surface area>

50 m²/g and with the totality or a part of possible other additives;

ii. optionally, if not already in the molten state, bringing the polymeric mixture to a temperature higher than the melting point of the thermoplastic polymer;

iii. incorporating in the molten polymer, said expanding agent and possibly the remaining portion or the totality of said other additives;

iv. mixing the polymeric composition thus obtained by means of static or dynamic mixing elements; and

v. granulating the composition thus obtained in a device which comprises a die, a cutting chamber and a cutting system.

22. The process according to claim 21, wherein the athermanous filler comprises, in addition to said nano-scaled graphene plates, up to 6% by weight, calculated with respect to the polymer, of said further athermanous additives respectively, such as graphite and/or carbon coke and/or carbon black, as synergic products.

23. The process according to claim 21 or 22, wherein at the end of the granulation, granules/beads of substantially spherical expandable thermoplastic polymer are obtained, with an average diameter ranging from 0.2 to 2.3 mm in which said athermanous filler and said possible further athermanous additives are homogeneously dispersed.

24. The process according to claim 21, 22 or 23 wherein the thermoplastic polymer is a vinyl aromatic polymer in the molten state, fed in continuous from the polymerization plant in solution.

25. The process according to any of the claims from 16 to 24, wherein said athermanous additives are incorporated in a master-batch comprising a thermoplastic polymer having an average molecular weight MW ranging from 50,000 to 300,000.

26. The process according to claim 25, wherein the content of athermanous filler, comprising said nano-scaled graphene plates and possibly said graphite and/or carbon coke and/or carbon black, ranges from 15 to 60% by weight.

27. The process according to any of the claims from 16 to 20, wherein the master-batch in pellets is dissolved in the vinyl aromatic monomer.

28. The process according to claim 24, wherein the master-batch in pellets is dissolved in the vinyl aromatic monomer/solvent mixture before this is fed to the reactor of the polymerization in solution.

33. The process according to any of the claims from 29 to 32, wherein the thermoplastic polymer in pellets or granules or beads and said athermanous filler are replaced, either totally or partially, by the compositions of thermoplastic polymers in beads/granules described or prepared according to any of the claims from 1 to 28.

12. Expanded extruded sheets of thermoplastic polymers comprising a cellular matrix having a density ranging from 10 to 200 g/l, an average cell dimension ranging from 0.01 to 1.00 mm and containing from 0.004 to 15% by weight, calculated with respect to the thermoplastic polymer, of said athermanous filler comprising said nano-scaled graphene plates with a thickness (orthogonal to the graphene sheet) not greater than 150 nm, an average dimension (length, width, or diameter) not greater than 10 micrometers and a surface area>

50 m²/g.

13. The extruded sheets according to claim 12, wherein the thermoplastic polymer is selected from a vinyl polymer and a vinyl aromatic polymer.

14. The extruded sheets according to claim 13, wherein the thermoplastic polymer is a vinyl aromatic polymer.

15. The extruded sheets according to claim 12, 13 or 14, wherein said athermanous filler comprises, in addition to said nano-scaled graphene plates, up to 6% by weight, calculated with respect to the polymer, of said further athermanous additives respectively, such as graphite and/or carbon coke and/or carbon black, as synergic products.

29. A process for the production of the expanded extruded sheets of thermoplastic polymers, according to claims 12-15, which comprises:

a1. mixing a thermoplastic polymer in pellets or granules or beads and at least said athermanous filler comprising said nano-scaled graphene plates with a thickness (orthogonal to the graphene sheet) not greater than 150 nm, an average dimension (length, width, or diameter) not greater than 10 micrometers and a surface area>

50 m²/g;

b1. heating the mixture (a1) to a temperature ranging from 180 to 250°

C. so as to obtain a molten polymer which is subjected to homogenization;

c1. adding to the polymeric melt, at least one expanding agent and possibly said other further additives, for example said flame-retardant system;

d1. homogenizing the polymeric melt which englobes at least the expanding agent;

e1. homogeneously cooling the polymeric melt (d1) to a temperature not higher than 200°

C. and not lower than the Tg of the resulting polymeric composition;

f1. extruding the polymeric melt through a die in order to obtain a polymeric expanded sheet.

30. The process according to claim 29, wherein the thermoplastic polymer is selected from a vinyl or vinyl aromatic polymer.

31. The process according to claim 29, wherein the vinyl polymer is polyethylene and the vinyl aromatic polymer is polystyrene.

32. The process according to any of the claims from 29 to 31, wherein said athermanous filler added to the vinyl aromatic polymer comprises up to 6% by weight, calculated with respect to the polymer, of said further athermanous additives respectively, such as graphite and/or carbon coke and/or carbon black, as synergic products.

34. The process according to any of the claims from 29 to 33, wherein said athermanous filler is used as master-batch.