# US 11,993,690 B2 · Polyamide-based resin expanded beads and molded article of polyamide-based resin expanded beads

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- Number: US 11,993,690 B2
- Document ID: US11993690B2
- Status: Granted
- Kind: B2
- Application number: 17/168,762
- Filed: 2021-02-05
- Published: 2021-08-19
- Granted: 2024-05-28
- Earliest claimed: 2020-02-18
- Assignees: Jsp Corporation
- Applicants: Jsp Corporation
- Inventors: Tatsuya Hayashi
- Web page: https://patentgrep.com/patent/US11993690B2

## CPC

- C08J 9/18: by impregnating polymer particles with the blowing agent
- C08J 9/228: Forming foamed products
- C08J 9/122: {Hydrogen, oxygen, CO2, nitrogen or noble gases}
- C08J 2201/03: Extrusion of the foamable blend
- C08J 2203/06: CO2, N2 or noble gases
- C08J 2203/14: Saturated hydrocarbons, e.g. butane; Unspecified hydrocarbons
- C08J 2377/00: Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)

## Abstract

The polyamide-based resin expanded beads are expanded beads including a polyamide-based resin as a base resin, in which the average value of bead weight of the expanded beads is 0.5 mg or more and 8 mg or less, the coefficient of variation of the bead weight of the expanded beads is 10% or less, and the average value of the ratio of a long diameter to a short diameter (a long diameter/a short diameter) of the expanded beads measured with a projection image photographing type bead size distribution analyzer is 1 or more and 1.5 or less, the coefficient of variation of the ratio (a long diameter/a short diameter) is 12% or less, the average value of the a short diameter is 1 mm or more and 4 mm or less, and the coefficient of variation of the a short diameter is 10% or less.

## Claims

### Claim 1

Polyamide-based resin expanded beads that are expanded beads, comprising
a polyamide-based resin as a base resin, wherein
the average value of bead weight of the expanded beads is 0.5 mg or more and 8 mg or less, and the coefficient of variation of the bead weight is 10% or less, and
the average value of the ratio of a long diameter to a short diameter (a long diameter/a short diameter) of the expanded beads measured with a projection image photographing type bead size distribution analyzer is 1 or more and 1.5 or less, the coefficient of variation of the ratio (a long diameter/a short diameter) is 12% or less, the average value of a short diameter is 1 mm or more and 4 mm or less, and the coefficient of variation of a short diameter is 10% or less.

### Claim 2 (depends on 1)

The polyamide-based resin expanded beads according to claim 1, wherein the average value of bead weight of the expanded beads is 0.5 mg or more and 3 mg or less.

### Claim 3 (depends on 1)

The polyamide-based resin expanded beads according to claim 1, wherein the polyamide-based resin is a modified polyamide-based resin modified with one or more compounds selected from among a carbodiimide compound, an oxazoline compound, an isocyanate compound, and an epoxy compound.

### Claim 4 (depends on 1)

The polyamide-based resin expanded beads according to claim 1, comprising a crystalline structure that exhibits, in a DSC curve obtained under the following condition 1, a melting peak intrinsic to the polyamide-based resin (an intrinsic peak) and a melting peak having a peak temperature on the higher temperature side than the peak top temperature of the intrinsic peak (a high temperature peak):
(Condition 1)
Based on the heat flux differential scanning calorimetry of JIS K7121-1987, polyamide-based resin expanded beads as a test piece were melted by heating from 30° C. to a temperature 30° C. higher than the end of the melting peak at a heating rate of 10° C./minute, and the DSC curve is measured.

### Claim 5 (depends on 1)

The polyamide-based resin expanded beads according to claim 1, wherein the coefficient of variation of the ratio (a long diameter/a short diameter) is 10% or less.

### Claim 6 (depends on 1)

The polyamide-based resin expanded beads according to claim 1, wherein the polyamide-based resin expanded beads have an apparent density of 10 kg/m3 or more and 300 kg/m3 or less.

### Claim 7 (depends on 1)

The polyamide-based resin expanded beads according to claim 1, wherein the polyamide-based resin has a melting point of 180° C. or higher.

### Claim 8 (depends on 1)

A molded article of polyamide-based resin expanded beads formed by in-mold molding of the polyamide-based resin expanded beads according to claim 1.