Hipe foam and method for producing same

Patent metadata

Field	Value
Publication number	US-12590176-B2
Application number	US-202117760410-A
Country	US
Kind code	B2
Filing date	Feb 17, 2021
Priority date	Feb 17, 2020
Publication date	Mar 31, 2026
Grant date	Mar 31, 2026

Abstract

A HIPE foam may including a vinyl-based crosslinked polymer as a base material resin. The vinyl-based crosslinked polymer may be formed by crosslinking a polymer of a styrene-based monomer and/or an acryl-based monomer. An apparent density ρ of the HIPE foam may be 35 kg/m 3 or more and 500 kg/m 3 or less. A molecular weight between crosslinking points of the vinyl-based crosslinked polymer forming the HIPE foam may be 2×10 3 or more and 2×10 5 or less. The HIPE foam may be used as, for example, a machinable material or an impact absorbing material.

First claim

The invention claimed is:

1 . A HIPE foam comprising, as a base material resin:
a crosslinked polymer formed by crosslinking a polymer comprising in polymerized form, (i-a) a styrene-based monomer and/or (i-b) an acryl-based monomer as a vinyl-based monomer which is monofunctional, and (ii) a crosslinking agent comprising a first and a second functional group comprising a vinyl group and/or an isopropenyl group, wherein a glass transition temperature of the crosslinked polymer is 60° C. or higher, wherein a molecular weight between crosslinking points of the crosslinked polymer is 2×10 3 or more and 2×10 4 or less, wherein an apparent density p of the HIPE foam is 35 kg/m 3 or more and 500 kg/m 3 or less, wherein a value S/ρ of Charpy impact strength S of the HIPE foam per apparent density ρ of the HIPE foam is 4.5 J·m/kg or more, and wherein a value E′/ρ of a storage elastic modulus E′ at 23° C. of the HIPE foam per apparent density ρ of the HIPE foam is 50 kN·m/kg or more.

2 . The HIPE foam of claim 1 , wherein an average diameter of cells of the HIPE foam is 20 μm or more and 100 μm or less.

3 . The HIPE foam of claim 1 , wherein an average value of the numbers of cells per unit area in the HIPE foam is 120 cells/mm 2 or more and 2400 cells/mm 2 or less.

4 . The HIPE foam of claim 1 , wherein the crosslinked polymer is a copolymer of the styrene-based monomer (i-a) and the acryl-based monomer (i-b), and
wherein the acryl-based monomer (i-b) is an ester of (meth)acrylic acid and an alcohol having 1 to 20 carbon atoms.

5 . The HIPE foam of claim 1 , wherein the crosslinking agent comprises, in crosslinked form,
a first crosslinking agent having a functional group equivalent of 130 g/mol or less, and a second crosslinking agent having a functional group equivalent of more than 130 g/mol and 5000 g/mol or less.

6 . A machinable material, comprising:
the HIPE foam of claim 1 .

7 . An impact absorbing material, comprising:
the HIPE foam of claim 1 , wherein a glass transition temperature of the crosslinked polymer is 60° C. or higher, wherein an apparent density of the HIPE foam is 35 kg/m 3 or more and less than 100 kg/m 3 , and wherein a ratio of compressive stress at a strain of 10% to compressive stress at a strain of 50% at 23° C. in the HIPE foam is more than 0.70 and 1.0 or less.

8 . A method for producing the HIPE foam of claim 1 , the method comprising:
forming a high internal phase water-in-oil emulsion in which an aqueous phase comprising water is comprised in an organic phase comprising the styrene-based monomer and/or the acryl-based monomer, a crosslinking agent, an emulsifier, and a polymerization initiator; and polymerizing the styrene-based monomer (i-a) and/or the acryl-based monomer (i-b) in the emulsion, wherein the crosslinking agent (if) comprises a first crosslinking agent having a functional group equivalent of 130 g/mol or less and a second crosslinking agent having a functional group equivalent of more than 130 g/mol and 5000 g/mol or less, wherein the crosslinking agent (ii) is present in the polymerizing in an amount of 7 parts by weight or more and 27 parts by weight or less, based on a total of 100 parts by weight of the styrene-based monomer (i-a), the acryl-based monomer (i-b), and the crosslinking agent (ii), wherein the first crosslinking agent is present in the polymerizing in an amount of 3 parts by weight or more and 17 parts by weight or less, based on a total of 100 parts by weight of the styrene-based monomer (i-a), the acryl-based monomer (i-b), and the crosslinking agent (ii), and wherein a weight ratio of the first crosslinking agent to the second crosslinking agent is 0.3 or more and 5 or less.

9 . The method of claim 8 , wherein the functional group equivalent of the second crosslinking agent is larger than the functional group equivalent of the first crosslinking agent by 60 g/mol or more.

10 . The method of claim 8 , wherein the second crosslinking agent is present in the polymerizing in an amount of 2 parts by weight or more and 18 parts by weight or less, based on a total of 100 parts by weight of the styrene-based monomer (i-a), the acryl-based monomer (i-b), and the crosslinking agent (ii).

11 . The method of claim 8 , wherein the second crosslinking agent is at least one compound selected from the group consisting of polyethylene glycol (meth)acrylate, urethane (meth)acrylate, epoxy (meth)acrylate, and (meth)acrylic-modified silicone.

12 . The method of claim 8 , wherein the first crosslinking agent is divinylbenzene.

13 . The method of claim 8 , wherein the acryl-based monomer (i-b) is an ester of (meth)acrylic acid and an alcohol having 1 to 20 carbon atoms.

14 . The method of claim 8 , wherein a content of the aqueous phase in the high internal phase emulsion is 300 parts by weight or more and 3000 parts by weight or less, based on 100 parts by weight of the organic phase.

15 . The method of claim 8 , wherein the second crosslinking agent comprises polyethylene glycol (meth)acrylate, urethane (meth)acrylate, epoxy (meth)acrylate, and/or (meth)acrylic-modified silicone.

16 . The HIPE foam of claim 1 , wherein styrene and/or methyl methacrylate is comprised as the vinyl-based monomer, and
wherein the styrene and/or the methyl methacrylate is present in the vinyl-based monomer in an amount of 40 wt % or more.

17 . The HIPE foam of claim 1 , wherein the crosslinked polymer forming the HIPE foam has a glass transition temperature of 60° C. or higher and 120° C. or lower, and
wherein a density of the HIPE foam is in a range of from 70 to 500 kg/m 3 .

18 . The HIPE foam of claim 1 , wherein the crosslinked polymer is formed by crosslinking a polymer of the styrene-based monomer (i-a).

19 . The HIPE foam of claim 1 , wherein the crosslinking agent comprises a vinyl functional group and an isopropenyl functional group.

20 . The HIPE foam of claim 1 , wherein the crosslinking agent comprises a first vinyl functional group and a second vinyl functional group.

Assignees

• Jsp Corp

Inventors

• Kaneko Yohei
• Haraguchi Kenji

Classifications

• C08J9/22

  After-treatment of expandable particles; Forming foamed products · CPC title

• C08F218/04

  Vinyl esters · CPC title

• C08F212/08

  Styrene · CPC title

• C08F2/32

  Polymerisation in water-in-oil emulsions · CPC title

• C08J2201/05

  Elimination by evaporation or heat degradation of a liquid phase · CPC title