Process for preparing a polymer to make refrigerator interior liners

摘要

A refrigerator interior liner can be made of a composition including a monovinylaromatic polymer matrix having an average molecular weight in weight Mwabove 150,000 g/mol; rubber particles; and low- Mwplasticizers. The rubber particles can have an RPS volume of about 8.5 μm, a monomodal distribution, a swell index above 13.8, and an RPVF of at least 39%. The composition can be prepared by forming a polymerizable mixture including a monovinylaromatic monomer, and dissolving a viscous rubber in the polymerizable mixture. A free radical initiator and a chain transfer agent can be contacted with the polymerizable mixture at conditions whereby phase inversion subsequently occurs. The chain transfer agent can produce an increase of the rubber to PS phase viscosity ratio within the inversion reactor. Polymerization can be continued until a monovinylaromatic polymer matrix having rubber particles dispersed therein is obtained.

主权项

1. A process for preparing a high impact monovinylaromatic polymer comprising:
a) forming a polymerizable mixture comprising monovinylaromatic monomers and optionally one or more comonomers, b) dissolving at least a viscous rubber of essentially linear structure in said polymerizable mixture to form a rubber containing polymerizable solution, c) contacting a free radical initiator and a chain transfer agent with the rubber containing polymerizable mixture at conditions whereby phase inversion subsequently occurs, wherein the chain transfer agent is capable to produce an increase of the rubber to polystyrene phase viscosity ratio within an inversion reactor, d) continuing the polymerization of the solution obtained at step c), optionally in the presence of a free radical initiator, until a monovinylaromatic polymer matrix having rubber particles dispersed therein is obtained, wherein the rubber particles have a monomodal distribution with essentially no shoulder, a volume median particle size (RPS volume) of from 7 to 10 μm, a surface median particle size (RPS surface) of from 5 to 8 μm, a ratio of RPS volume-to-RPS surface that is below 2, and a rubber phase volume fraction (RPVF) of at least 39%.