Thermally expandable microcapsule and foam-molded article

摘要

A thermally expandable microcapsule, which shows excellent heat resistance and a high expansion ratio and thereby can be suitably used for molding processes involving high shearing force, such as kneading molding, calender molding, extrusion molding, and injection molding. The thermally expandable microcapsule also provides a foamed product using the thermally expandable microcapsule. The thermally expandable microcapsule contains a shell made of a polymer; and a volatile expansion agent as a core agent encapsulated in the shell, the storage elastic modulus (E′) of the shell at a temperature of 200° C. and a frequency of 10 Hz being 1×105 N/m2 or more, the storage elastic modulus (E′) of the shell at a temperature of 250° C. and a frequency of 10 Hz being 1×105 N/m2 or more, and a maximum displacement amount measured by thermomechanical analysis being 300 μm or more.

主权项

1. A thermally expandable microcapsule, which comprises:
a shell made of a polymer; and a volatile expansion agent as a core agent encapsulated in the shell, a storage elastic modulus (E′) of the shell at a temperature of 200° C. and a frequency of 10 Hz being 1 ×105 N/m2 or more, the storage elastic modulus (E′) of the shell at a temperature of 250° C. and a frequency of 10 Hz being 1 ×105 N/m2 or more, and a maximum displacement amount measured by thermomechanical analysis being 300μm or more, wherein the shell comprises a polymer obtainable by polymerizing a monomer mixture that contains 95% by weight or more of a mixture of acrylonitrile and methacrylonitrile,
wherein the mixture of acrylonitrile and methacrylonitrile contains 70% by weight or more of acrylonitrile relative to the total weight of the mixture of acrylonitrile and methacrylonitrile, andwherein a degree of crosslinkage is 60% by weight or more.