Back to results
US 6,274,641 B1Granted
Tetrafunctional initiator
AssigneeNova Chemical Corporation
InventorSteven M. Krupinski
Life of this patent
Estimating the term…
Abstract
The melt of polyvinyl aromatic polymers comprising from 10 to 45 weight % of star branched polymer prepared using a combination of thermal and tetra functional peroxide initiation has an improved melt strength permitting better foam formation for extrusion foam blown with conventional blowing agents and inert gases including CO2.
Claims30
A process for preparing a closed cell foam comprising injection into a molten mass of C8-12 vinyl aromatic polymer comprising:
- i) from 60 to 100 weight % of one or more C8-12 vinyl aromatic monomers;
- and
- ii) from 0 to 40 weight % of one or more monomers selected from the group consisting of C1-4 alkyl esters of acrylic or methacrylc acid and acrylonitrile and methacrylonitrile;
- which polymers are grafted onto from 0 to 12 weight % of one or more rubbery polymers selected from the group consisting of:
- iii) co- and homopolymers of C4-5 conjugated diolefins;
- and
- iv) copolymers comprising from 60 to 85 weight % of one or more C4-5 conjugated diolefins and from 15 to 40 weight % of a monomer selected from the group consisting of acrylonitrile and methacrylonitrile, said polymer comprising 10 to 45 weight % of a star branched polymer and having a VICAT softening temperature not less than 100° C.;
- at a temperature from 140 to 235° C. and a pressure from 1500 to 3500 psi from 2 to 15 weight % of one or more blowing agents selected from the group consisting of C4-6 alkanes, CFCs, HCFCs, HFCs, CO2, N2 and mixtures thereof and maintaining said
- C8-12 vinyl aromatic polymer in a molten state and thoroughly mixing said blowing agent with said polymer and extruding said mixture of blowing agent and polymer.
6 more elements
A process for polymerizing a vinyl aromatic monomer comprising from 5 to 45 weight % of star branched vinyl aromatic polymer comprising feeding a mixture comprising:
- i) from 60 to 100 weight % of one or more C8-12 vinyl aromatic monomers;
- and
- ii) from 0 to 40 weight % of one or more monomers selected from the group consisting of C1-4 alkyl esters of acrylic or methacrylc acid and acrylonitrile and methacrylonitrile;
- which polymer may be grafted onto or occluded within from 0 to 12 weight % of one or more rubbery polymers selected from the group consisting of:
- iii) co- and homopolymers of C4-5 conjugated diolefins;
- and
- iv) copolymers comprising from 60 to 85 weight % of one or more C4-5 conjugated diolefins and from 15 to 40 weight % of a monomer selected from the group consisting of acrylonitrile and methacrylonitrile, and from 0.01 to 0.1 weight % of a tetrafunctional peroxide initiator of the formula:
- wherein R1 is selected from the group consisting of C4-6 t-alkyl radicals and R is a neopentyl group, in the absence of a cross linking agent to a series of two or more continuous stirred tank reactors, to provide a relatively low temperature initial reaction zone at a temperature from 100 to 130° C. and a relatively higher temperature subsequent reaction zone at a temperature from 130 to 160° C. and maintaining a ratio of residence time in said relatively lower temperature reaction zone to said relatively higher temperature reaction zone from 1:1 to 4:1 and recovering the resulting polymer.
5 more elements
Dependencies are inferred from the claim text.