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US 9,068,036 B2Granted
Process for core-shell impact modifiers and impact modified thermoplastic composition with enhanced hydrolytic resistance
AssigneeArkema France
InventorsChristophe Navarro, Stephane Girois, Elisabeth Bay, Jean-Claude Saint-Martin
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Abstract
The present invention relates to a process for producing impact modifiers, impact modified thermoplastic molding compositions and in particular impact modified polycarbonate or polycarbonate/polyester blends having improved resistance to degradation. More particularly the present invention relates to a process for producing polymeric impact modifiers with a core-shell structure made by a multistage process comprising a control and adjustment if necessary of the pH value before and during the recovery step.
Claims19
A thermoplastic polymer composition comprising
- a) one thermoplastic polymer, and
- b) a core-shell impact modifier obtained by a process comprising the steps of:
- i) synthesizing a core-shell copolymer latex by emulsion polymerization;
- ii) controlling and adjusting of pH value of the core shell polymer particle after the synthesis step;
- iii) coagulation of the core shell polymer at a pH between 4 and 8 by addition of an aqueous electrolyte solution,
- whereby said resulting core-shell impact modifier comprises a polymeric core and at least two polymeric layers surrounding said core, each layer having a different polymer composition from the other layer and, wherein at least one polymeric layer comprises a polymer that is a gradient polymer, said gradient polymer being a copolymer consisting of at least two different monomers (A) and (B) and having a gradient in repeat units arranged from mostly said monomer (A) to mostly said monomer (B) along the copolymer.
3 more elements
Dependencies are inferred from the claim text.