Process for production of polymer nanocomposites
View Patent ↗The invention relates to a processes for preparing nanocomposites comprising rubber ionomers which were prepared by an energy efficient, environmentally favorable process that uses a common medium for solution polymerization, bromination of rubber and optionally subsequent polymer nanocomposite formation. Polymer nanocomposites according to the present invention exhibit high oxygen impermeability.
1. A process for the preparation of polymer nanocomposites comprising:
a) providing a reaction medium comprising
a common aliphatic medium comprising at least 50 wt.-% of one or more aliphatic hydrocarbons having a boiling point of 45° C. to 80° C. at a pressure of 1013 hPa, and
a monomer mixture comprising at least one monoolefin monomer, at least one multiolefin monomer and either no or at least one other co-polymerizable monomer in a mass ratio of monomer mixture to common aliphatic medium of 40:60 to 95:50;
b) polymerizing the monomer mixture within the reaction medium to form a rubber solution comprising a rubber polymer which is at least substantially dissolved in the medium comprising the common aliphatic medium and residual monomers of the monomer mixture;
c) separating residual monomers of the monomer mixture from the rubber solution to form a separated rubber solution comprising the rubber polymer and the common aliphatic medium;
d) brominating the rubber polymer in the separated rubber solution to obtain a solution comprising the brominated rubber polymer and the common aliphatic medium;
e) reacting the brominated rubber polymer obtained in step d) with at least one nitrogen and/or phosphorous containing nucleophile; and
f) adding a filler to the ionomer obtained in step e), and mixing the filler and the ionomer to form an uncured nanocomposite.
2. The process according to claim 1 , wherein the rubber polymer is a butyl rubber.
3. The process according to claim 2 wherein the weight average molecular weight of butyl rubber, as measured prior to bromination, is 200 kg/mol to 1000 kg/mol.
4. The process according to claim 1 wherein ft monomer mixture comprises 80.0% to 99.9% by weight of at least one monoolefin monomer and 0.1% to 20.0% by weight of at least one multiolefin monomer.
5. The process according to claim 1 wherein the monoolefin monomer is isobutene and the multiolefin monomer is isoprene.
6. The process according to claim 1 wherein the common aliphatic medium comprises at least 80 wt.-% of one or more aliphatic hydrocarbons having a boiling point of 45° C. to 80° C. at a pressure of 1013 hPa.
7. The process according to claim 1 wherein the polmerizing of step b) is conducted at a process temperature of −100° C. to −40° C.
8. The process according to claim 1 further comprising conducting the reaction in a polymerization reactor, and wherein the viscosity of the solution at the discharge of the polymerization reactor is less than 2000 cP.
9. The process according to claim 1 wherein the rubber solution obtained in step b) has a solids content of 3 to 25%.
10. The process according to claim 1 wherein the brominating comprises brominating the rubber polymer in the presence of molecular bromine as a brominating agent.
11. The process according to claim 10 further comprising using an amount of brominating agent of 0.1 to 20% by weight of the rubber.
12. The process according to claim 11 further comprising using the brominating agent in combination with an oxidizing agent.
13. The process according to claim 1 wherein the nitrogen and/or phosphorous containing nucleophiles are those of formula I
AR 1 R 2 R 3 (I), wherein:
A denotes nitrogen or phosphorus, and
R 1 , R 2 and R 3 are, independently of each other, selected from the group consisting of C 1 -C 18 -alkyl, C 6 -C 15 -arylalkyl or C 5 -C 14 -aryl.
14. The process according to claim 1 wherein further comprising conducting steps e) and f) simultaneously.
15. The process according to claim 1 wherein the fillers are selected from the group of high aspect ratio fillers.
16. The process according to claim 1 wherein the filler has a BET surface area, measured in accordance with DIN (Deutsche Industrie Norm) 66131, of 5 to 200 square meters per gram.
17. The process according to claim 1 further comprising curing the uncured nanocomposite.