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US 5,534,594 AGranted
Preparation of butadiene-based impact modifiers
AssigneeRohm and Haas Company
InventorsEdward J. Troy, Anibal Rosado
Life of this patent
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Abstract
An improved process for preparing core/shell MBS modifiers is disclosed, wherein by adding feeds of the monomers which form the second and/or third stage polymers prior to completion of polymerization of the earlier stages, a process with substantially reduced polymerization time results with no loss in properties of the product. The process further includes agglomeration of the rubbery polymer to increase particle size during the polymerization process.
Claims11
A process for preparing a core/shell impact modifier which comprises:
- a. polymerizing in emulsion, in a pressure vessel, a first mixture of monomers, comprising at least 40% butadiene, and further comprising at least one polyunsaturated monomer for controlling the crosslinking of the polybutadiene, in the presence of an emulsifier and a free-radical initiator, until 60%-90% conversion of the monomers to polymer and a particle size of 120-240 nm. have been achieved;
- b. continuing the polymerization of the first mixture of monomers while adding a second mixture of monomers which mixture comprises at least one of a C.sub.1 -C.sub.4 alkyl methacrylate;
- and
- c. continuing the polymerization of the second mixture of monomers to at least 80% conversion to polymer.
1 more element
A process for preparing a core/shell impact modifier which comprises:
- a. polymerizing in emulsion, in a pressure vessel, a first mixture of monomers, comprising at least 40% butadiene, and further comprising at least one polyunsaturated monomer for controlling the crosslinking of the polybutadiene, in the presence of an emulsifier and a free-radical initiator, until 60%-90% conversion of the monomers to polymer and a particle size of 120-240 nm. have been achieved;
- b. continuing the polymerization of the first mixture of monomers while adding a second mixture of monomers which mixture comprises at least one of a C.sub.1 -C.sub.4 alkyl methacrylate or a vinyl aromatic monomer;
- c. continuing the polymerization of the second mixture of monomers to at least 80% conversion to polymer;
- d. beginning addition of a third mixture of monomers, which mixture comprises at least one of a C.sub.1 -C.sub.4 alkyl methacrylate or a vinyl aromatic monomer;
- and
- e. continuing the polymerization to 60-100% conversion of all monomers present from the second and third monomer mixtures to polymer.
3 more elements
Dependencies are inferred from the claim text.