# US 8,785,510 B2 · Alkenyl aromatic foam with low solubility hydrofluorocarbon

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- Number: US 8,785,510 B2
- Document ID: US8785510B2
- Status: Granted
- Kind: B2
- Application number: 12/531,518
- Filed: 2008-03-13
- Published: 2010-04-22
- Granted: 2014-07-22
- Earliest claimed: 2007-04-16
- Assignees: Dow Global Technologies LLC
- Applicants: Van-Chau Vo; Richard T. Fox; Warren H. Griffin; John Gordon-Duffy; Lawrence S. Hood; Roy E. Smith
- Inventors: Van-Chau Vo; Richard T. Fox; Warren H. Griffin; John Gordon-Duffy; Lawrence S. Hood; Roy E. Smith
- Web page: https://patentgrep.com/patent/US8785510B2

## CPC

- C08J 9/127: {Mixtures of organic and inorganic blowing agents}
- C08J 9/144: {containing carbon, halogen and hydrogen only}
- C08J 9/146: {only fluorine as halogen atoms}
- C08J 9/149: {Mixtures of blowing agents covered by more than one of the groups C08J9/141 - C08J9/143}
- 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 2203/142: Halogenated saturated hydrocarbons, e.g. H3C-CF3
- C08J 2203/144: Perhalogenated saturated hydrocarbons, e.g. F3C-CF3
- C08J 2325/06: Polystyrene
- C08J 2325/08: Copolymers of styrene (C08J2329/08, C08J2335/06, C08J2355/02 take precedence)
- C08J 2325/12: with unsaturated nitriles
- 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

Prepare a closed-cell alkenyl aromatic polymer foam by an extrusion process using a blowing agent composition that contains at least 30 weight-percent of the chlorine-free hydrofluorocarbon blowing agent such that the foam has a density of 48 kilograms per cubic meter or less, contains more than 50 weight-percent styrene-acrylonitrile copolymer based on total polymer weight and at least eight weight-percent of a chlorine-free hydrofluorocarbon blowing agent that has a lower solubility in polystyrene than 1,1,2,2-tetrafluoroethane (HFC-134).

## Claims

### Claim 1

A process for preparing extruded polymer foam comprising the steps:
(a) preparing a foamable mixture of a thermoplastic polymer composition and blowing agent composition at a mixing temperature and mixing pressure in a range of 13.2 to 19.0 megaPascals;
(b) cooling the foamable mixture to a foaming temperature; and
(c) exposing the foamable mixture to an environment at a lower pressure than the mixing pressure and allowing the foamable mixture to expand into a polymer foam;
wherein, more than 95 wt % of the thermoplastic polymer composition is one or more styrene-acrylonitrile copolymer and wherein 1,1,1,2-tetrafluoroethane is present at a concentration of more than 30 weight-percent based on total blowing agent composition weight and at least eight weight-percent and 12 weight-percent or less based on thermoplastic polymer composition weight and wherein the polymer foam of step (c) is an extruded polymer foam comprising a thermoplastic polymer composition defining a plurality of cells therein, characterized by: (i) more than 95 weght-percent of the thermoplastic polymer composition is a styrene-acrylonitrile copolymer; (ii) having less than 30% open cell content according to ASTM method D6226-05; (iii) having a density of 48 kilograms per cubic meter or less according to ISO method 845-85; and (iv) containing at least eight weight-percent and 12 weight-percent or less, based on total foam weight, of 1,1,1,2-tetrafluoroethane.

### Claim 2 (depends on 1)

The process of claim 1, wherein the thermoplastic polymer composition is one or more styrene-acrylonitrile copolymer.

### Claim 3 (depends on 1)

The process of claim 1, wherein the thermoplastic polymer composition contains one weight-percent or more and 35 weight-percent or less of copolymerized acrylonitrile based on thermoplastic polymer composition weight.

### Claim 4 (depends on 1)

The process of claim 1, wherein the blowing agent composition consist of 50 weight-percent or more of 1,1,1,2-tetrafluoroethane and up to 50 weight-percent of a co-blowing agent selected from a group consisting of carbon dioxide, water, hydrocarbons having from one to seven carbons, alcohols having from two to five carbons, ether and ketones having from two to four carbons.

### Claim 5 (depends on 1)

The process of claim 1, wherein the blowing agent composition consists of 1,1,1,2-tetrafluoroethane.

### Claim 6 (depends on 1)

The process of claim 1, wherein the polymer foam has an open-cell content of less than 30 percent according to ASTM method D6226-05 and has a density of 32 kilograms per cubic meter or less according to ISO method 845-85.

### Claim 7 (depends on 6)

The process of claim 6, wherein the polymer foam has an average cell size of 0.1 millimeters or more according to ASTM method D-3756.

### Claim 8 (depends on 1)

The process of claim 1, wherein the concentration of 1,1,1,2-tetrafluoroethane is nine weight-percent or more and 12 weight-percent or less based on thermoplastic polymer composition weight.