# US 2019/0291314 A1 · Polymer foam processing including different types of blowing agent

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2019/0291314 A1
- Document ID: US20190291314A1
- Status: Published application
- Kind: A1
- Application number: 15/926,882
- Filed: 2018-03-20
- Published: 2019-09-26
- Earliest claimed: 2018-03-20
- Assignees: Trexel, Inc.
- Applicants: Trexel, Inc.
- Inventors: Samuel Edward Dix; Levi A. Kishbaugh
- Web page: https://patentgrep.com/patent/US20190291314A1

## CPC

- B29C 44/422: {by injecting by forward movement of the plastizising screw}
- B29C 44/3446: {Feeding the blowing agent}
- B29C 44/3449: {through the screw}
- B29C 44/3453: {Feeding the blowing agent to solid plastic material}
- B29C 44/60: Measuring, controlling or regulating
- C08J 9/08: developing carbon dioxide
- C08J 9/122: {Hydrogen, oxygen, CO2, nitrogen or noble gases}
- C08J 9/34: Chemical features in the manufacture of articles consisting of a foamed macromolecular core and a macromolecular surface layer having a higher density than the core
- B29K 2105/041: {Microporous}
- C08J 2201/03: Extrusion of the foamable blend
- C08J 2203/02: CO2-releasing, e.g. NaHCO3 and citric acid
- C08J 2203/06: CO2, N2 or noble gases
- C08J 2203/184: of chemical foaming agent and physical blowing agent, e.g. azodicarbonamide and fluorocarbon
- C08J 2205/044: Micropores, i.e. average diameter being between 0,1 micrometer and 0,1 millimeter
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- 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)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS

## Abstract

Injection molding methods used to form polymeric foam articles (e.g., microcellular foam articles) are described herein.

## Claims

### Claim 1

A method of molding a microcellular foam article comprising:
conveying a mixture comprising polymeric material and a chemical blowing agent in a downstream direction in a barrel of an extruder, wherein the chemical blowing agent is decomposable to form carbon dioxide and is present in an amount between 0.20 and 3.00 weight percent based on the total weight of polymeric material; and
introducing a physical blowing agent comprising nitrogen into the mixture, the nitrogen being present in an amount between 0.025 and 1.50 weight percent based on the total weight of polymeric material; and
injecting the mixture into a mold cavity of a mold; and
recovering an injection molded microcellular foam article from the mold cavity.

### Claim 2

A method of molding a microcellular foam article comprising:
conveying a mixture comprising polymeric material and a chemical blowing agent in a downstream direction in a barrel of an extruder, wherein the chemical blowing agent is decomposable to form carbon dioxide;
introducing a physical blowing agent comprising nitrogen into the mixture; and
injecting the mixture into a mold cavity of a mold; and
recovering an injection molded microcellular foam article from the mold cavity, the article having a thickness of less than 5 mm, a skin thickness of greater than 25% of the thickness of the article, and a void volume percentage of between 2% and 15%.

### Claim 3 (depends on 1)

The method of claim 1, wherein the microcellular foam article has an average cell size of less than 100 micron.

### Claim 4 (depends on 1)

The method of claim 1, wherein the mixture is a single-phase solution comprising the polymeric material, nitrogen, and carbon dioxide prior to injection into the mold.

### Claim 5 (depends on 1)

The method of claim 1, wherein the physical blowing agent comprising nitrogen blowing agent is present in an amount between 0.25 and 1.00 weight percent based on the total weight of the polymeric material.

### Claim 6 (depends on 1)

The method of claim 1, wherein the physical blowing agent comprising nitrogen blowing agent is present in an amount between 0.30 and 0.75 weight percent based on the total weight of the polymeric material.

### Claim 7 (depends on 1)

The method of claim 1, wherein the chemical blowing is present in an amount between 0.35 and 2.00 weight percent based on the total weight of the polymeric material.

### Claim 8 (depends on 1)

The method of claim 1, wherein the chemical blowing is present in an amount between 0.50 and 1.50 weight percent based on the total weight of the polymeric material′.

### Claim 9 (depends on 1)

The method of claim 1, wherein the chemical blowing agent comprises an acid and an alkali to produce carbon dioxide.

### Claim 10 (depends on 1)

The method of claim 1, wherein the chemical blowing agent is selected from the group consisting of citric acid, sodium bicarbonate, monosodium citrate, calcium carbonate and zinc stearate.

### Claim 11 (depends on 1)

The method of claim 1, wherein the chemical blowing agent is added to the mixture as a separate ingredient.

### Claim 12 (depends on 1)

The method of claim 1, wherein the microcellular foam article comprises a semi-crystalline polymer.

### Claim 13 (depends on 1)

The method of claim 1, wherein the microcellular foam article has a percentage elongation between 5% to 200%.

### Claim 14 (depends on 1)

The method of claim 1, wherein the microcellular foam article has a wall thickness of less than 3 mm.

### Claim 15 (depends on 1)

The method of claim 1, wherein the microcellular foam article has a skin thickness and a wall thickness and the skin thickness is greater than 50% of the wall thickness.

### Claim 16 (depends on 1)

The method of claim 1, wherein the microcellular foam article has a void volume percentage of between 2% and 15%.

### Claim 17 (depends on 1)

The method of claim 1, wherein the skin thickness of the microcellular foam article is in a range of 250 to 600 microns.

### Claim 18

An injection molded microcellular foam article comprising a semi-crystalline polymeric material, the article having an average cell size of less than 100 microns, a thickness of less than 5 mm, a skin thickness of greater than 25% of the thickness, a void volume percentage of between 2 and 15% and a percentage elongation between 5% and 200%.

### Claim 19 (depends on 18)

The article of claim 18, wherein the microcellular foam article has a wall thickness of less than 3 mm.

### Claim 20 (depends on 18)

The article of claim 18, wherein the microcellular foam article has a skin thickness and a wall thickness and the skin thickness is greater than 50% of the wall thickness.