| 主权项 |
1. Heat-expandable microspheres, each comprising
a shell of a thermoplastic resin and a thermally vaporizable blowing agent being encapsulated therein, wherein the thermoplastic resin comprises a copolymer produced by polymerizing a polymerizable component comprising a carboxyl-group-containing monomer, with an amount of N,N-dimethylformamide-insoluble matter contained in the heat-expandable microspheres being at least 75 weight percent, and the heat-expandable microspheres include treated surfaces having been treated with an organic compound that is soluble in water, the organic compound containing a metal M, the metal M being selected from a group of metals consisting of the Groups from 3 to 11 in the Periodic Table with the metal M of the organic compound forming cross-linked bonding to the surface of the heat-expandable microspheres, and prior to treating of the surfaces of the heat-expandable microspheres the metal-containing organic compound is a metal-amino acid compound and/or a compound having at least one bond represented by the following chemical formula (1),
M-O—C (1)(where “M” is an atom of a metal of the Groups from 3 to 11 in the Periodic Table; and the carbon atom, “C”, bonds to the oxygen atom, “O”, and also bonds only to a hydrogen atom and/or a carbon atom except the oxygen atom, “O”), and
the heat-expandable microspheres exhibit a first expansion-initiation at a first expansion-initiating temperature Ts1 in degrees C. and exhibit a greatest expansion rate at a maximum expansion temperature Tmax1 in degrees C., and the heat-expandable microspheres exhibit a second expansion-initiation at a second expansion-initiating temperature Ts2 in degrees C. and exhibit a second greatest expansion rate at a maximum expansion temperature Tmax2 in degrees C. as determined after dispersing 5 parts by weight of the microspheres in 100 part by weight of deionized water, and then filtering and drying, with a range of variation ΔTs between the first expansion-initiating temperature Ts1 and the second expansion-initiating temperature Ts2 being less than or equal to 10 percent of the expansion initiating temperature Ts1, and with a range of variation ΔTmax of the maximum expansion temperatures Tmax1 and Tmax2 of the heat-expandable microspheres being less than or equal to 10 percent of the maximum expansion temperature Tmax1, wherein the amount of the carboxyl-group-containing monomer is in the range of 30 to 90 percent and the polymerizable component further comprises a nitrile monomer. |
