Thermally-expandable microspheres, and composition and molded article containing same

Patent metadata

Field	Value
Publication number	US-10150849-B2
Application number	US-201515531613-A
Country	US
Kind code	B2
Filing date	Dec 8, 2015
Priority date	Dec 8, 2014
Publication date	Dec 11, 2018
Grant date	Dec 11, 2018

Abstract

Object:
To provide thermally expandable microspheres having little sag.
Resolution Means:
The thermally expandable microspheres have a structure in which a foaming agent is encapsulated in an outer shell formed from a polymer, wherein, the ratio (%) of (R2/R1)×100 is at least 105%, where R1 is the expansion ratio after the thermally expandable microspheres have been heat-treated for 5 minutes at 150° C. and then foamed by heating for 2 minutes at 200° C., and R2 is the expansion ratio after the thermally expandable microspheres have been heat-treated for 5 minutes at 150° C. and then foamed by heating for 4 minutes at 200° C.

First claim

The invention claimed is:

1. A thermally expandable microsphere having a structure in which a foaming agent is encapsulated in an outer shell formed from a polymer,
the outer shell being formed from (meth)acrylonitrile (co)polymer obtained by polymerizing polymerizable monomers and a crosslinkable monomer;
the polymerizable monomers being at least one type of nitrile monomer selected from the group consisting of acrylonitrile and methacrylonitrile as a main component and another vinyl monomer that is not methacrylic acid and that is copolymerizable with the nitrile monomer;
an amount of the crosslinkable monomer being from 0.9 to 1.4 parts by mass per 100 parts by mass of the polymerizable monomers;
the foaming agent being a mixed foaming agent containing an isododecane isomer mixture and an isooctane isomer mixture; and
a ratio (%) of (R2/R1)×100 being at least 105%, where R1 is an expansion ratio after the thermally expandable microsphere has been heat-treated for 5 minutes at 150° C. and then foamed by heating for 2 minutes at 200° C., and R2 is an expansion ratio after the thermally expandable microsphere has been heat-treated for 5 minutes at 150° C. and then foamed by heating for 4 minutes at 200° C.

2. The thermally expandable microsphere according to claim 1 , wherein the foaming agent further contains a saturated hydrocarbon having 7 or less carbons.

3. The microsphere according to claim 1 , wherein the foaming agent includes from 50 to 75 mass % of the isododecane isomer mixture and from 25 to 50 mass % of the isooctane isomer mixture.

4. The thermally expandable microsphere according to claim 2 , wherein the foaming agent includes from 45 to 55 mass % of the isododecane isomer mixture, from 30 to 41.5 mass % of the isooctane isomer mixture, and from 3.5 to 25 mass % of the saturated hydrocarbon having 7 or less carbons.

5. The thermally expandable microsphere according to claim 2 , wherein the saturated hydrocarbon having 7 or less carbons is an isopentane isomer mixture.

6. The thermally expandable microsphere according to claim 1 , wherein the polymerizable monomers are at least one type of nitrile monomer selected from the group consisting of acrylonitrile and methacrylonitrile as a main component and another vinyl monomer that is not a vinyl monomer having a carboxyl group and that is copolymerizable with the nitrile monomer.

7. The thermally expandable microsphere according to claim 1 , wherein the R1 is 60 or greater.

8. The thermally expandable microsphere according to claim 1 , wherein a foaming initiation temperature after the heat treatment for 5 minutes at 150° C. is 175° C. or lower.

9. A composition comprising the thermally expandable microsphere described in claim 1 , and at least one type of polymer material.

10. A molded article comprising a foamed particle obtained by foaming the thermally expandable microsphere described in claim 1 .

Assignees

• Kureha Corp

Inventors

• Suzuki Yasuhiro
• KURIU Naoko
• Nomura Shintaro
• Ejiri Tetsuo
• Endo Shunzo

Classifications

• C08J2433/20

  Homopolymers or copolymers of acrylonitrile (C08J2455/02 takes precedence) · CPC title

• C08J2203/182

  of physical blowing agents, e.g. acetone and butane · CPC title

• C08J2201/026

  Crosslinking before of after foaming · CPC title

• C08J2203/202

  of physical blowing agents · CPC title

• C08J2203/14

  Saturated hydrocarbons, e.g. butane; Unspecified hydrocarbons · CPC title