Processing aids for use in manufacturing extruded polystyrene foams using low global warming potential blowing agents

a technology of extrusion aids and blowing agents, which is applied in the field of polymeric foam manufacturing processes, can solve the problems of ozone depletion potential, and achieve the effect of increasing the prevalence of global warming

Inactive Publication Date: 2014-10-23
OWENS CORNING INTELLECTUAL CAPITAL LLC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]A new generation of fluroralkene blowing agents have been developed with low ODP (ozone depletion potential) and low GWP (global warming potential) known as hydroflouroolefins (HFOs). HFOs have been identified as potential low global warming potential blowing agents for the production of thermoplastic foams, such as polystyrene foam, for thermal insulation.
[0010]The general inventive concepts are directed to a foamable polymeric mixture. The foamable polymeric mixture comprises a polymer composition, such as a polystyrenic composition and at least one blowing agent. The blowing agent may comprise any blowing agents known not to deplete the ozone or increase the prevalence of global warming. Such blowing agents may consist of, for example, carbon dioxide, hydrofluoroolefins, and hydrofluorocarbons, along with mixtures thereof. The foamable polymeric mixture may further includes at least one processing aid comprising an organic phase changing material. The inventive foamable mixture is capable of processing at a pressure range of 800 to 1200 psi (5.5 to 8.3 MPa).
[0011]The general incentive concepts further relate to a method of manufacturing extruded polymeric foam. The method includes introducing a polymeric composition into a screw extruder to form a polymer melt and injecting at least one organic phase changing processing aid and at least one blowing agent into the polymer melt to form an foamable polymeric material. The blowing agent preferably comprises one or more low ozone depletion and low global warming potential compounds, such as carbon dioxide, hydrofluorocarbon, hydrofluoroolefin, and mixtures thereof. The method further includes extruding the foamable polymeric composition through a die under a processing temperature between 800 and 1200 psi (5.5 to 8.3 MPa) to produce a polymeric foam.
[0012]Further inventive concepts relate to an extruded polymeric foam. The extruded polymeric foam is formed from a foamable polymer material that includes a polymeric composition, at least one blowing agent, and an organic phase changing processing aid. The blowing agent may include one or more of carbon dioxide, hydrofluoroolefin, hydrofluorocarbon, and mixtures thereof. The processing aid may comprise an organic phase changing material. It is an object of the present invention that wherein said foam has an R-value between 4 and 7 per inch.

Problems solved by technology

However, while HCFC's are considered to be environmentally friendly blowing agents compared to CFCs, such compounds do still contain some chlorine and are therefore said to have an ozone depletion potential.

Method used

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  • Processing aids for use in manufacturing extruded polystyrene foams using low global warming potential blowing agents
  • Processing aids for use in manufacturing extruded polystyrene foams using low global warming potential blowing agents
  • Processing aids for use in manufacturing extruded polystyrene foams using low global warming potential blowing agents

Examples

Experimental program
Comparison scheme
Effect test

example 1

Operating Window Expansion with Phase Changing Materials in CO2 Foaming

[0057]One percent of PT24 microencapsulated powder containing 80% phase changing material and 20% encapsultion wall material was applied for XPS foaming using about 3.7-4.3% CO2 blowing agent. A foam board with a 1 inch thickness was produced smoothly and the properties of the resulting foam board are shown as Samples 1 & 2 in Table 2 below. The foam board properties are each within the acceptable range for traditional foam borads. Particulalry, the boards have a density between about 1.4 and 3 psi, an R-value of 4-7 per inch. a cell size between about 0.005 and 0.6 mm, a compressive strength between about 6 and 80 psi, and an open cell content of less than 30 percent. On the contrary, without the phase changing material, the process could not be continued under the similar processing conditions due to the overshooting of die pressure (Sample #3). This observation indicates that phase changing materials are neces...

example 2

Application of PT24 Liquid in CO2 Foaming

[0058]A liquid processing aid, PT24, was injected directly into the extruder with 3.5% CO2 as the blowing agent. An XPS foam board with good surface quality was produced without any modification to the traditional foaming conditions. The foam board properties are illustrated below, in Table 3. This further proves the benefit of using the subject phase changing materials as a processing aid when using CO2 as the blowing agent.

TABLE 3Application of PT24 liquid for CO2 XPS foamingFoamCellCompressiveSamplePT24 liquiddensityRsizeOpen cellstrength#(wt %)(pcf)value(mm)(%)(psi)40.82.814.410.161.9936.651.22.774.390.175.9432.661.62.784.410.176.3132.8

example 3

Design of Experiment (DOE) of Using PT24 Microencapsulated Powder in CO2 Foaming

[0059]A Design of Experiment (“DOE”) was developed to understand the influence that phase changing processing aids have on foam properties. A DOE is an information gathering exercise where one or more variations are present. The particular DOE designed was based on three key parameters: phase changing material usage level (between 1 and 3 weight %), polystyrene melt flow index, and CO2 concentration. A single DOE having three factors and two levels (low and high) was performed.

[0060]The main effects from the three key parameters to foam density, foam cell size, and compressive strength are summarized in FIGS. 3, 4, &5, respectively. FIG. 3 illustrates the effects the various parameters have on foam density when exposed to both low and high levels. For instance, at a high polystyrene melt flow index, the foam density is also high. Conversely, as the CO2 or phase changing material concentration increases, ...

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Abstract

A foamable polymeric mixture is provided that includes a polymer composition and at least one blowing agent. The blowing agent may comprise any blowing agents known not to deplete the ozone or increase the prevalence of global warming, such as CO2, HFO, HFC and mixtures thereof. The foamable polymeric mixture may further includes at least one processing aid comprising an organic phase changing material. The inventive foamable mixture is capable of processing at a pressure range of 800 to 1200 psi (5.5 to 8.3 MPa).

Description

RELATED APPLICATIONS[0001]This application claims priority from provisional application No. 61 / 786,965 filed on Mar. 15, 2013, titled “Processing Aids for Use in Manufacturing Extruded Polystyrene Foams Using Low Global Warming Potential Blowing Agents.” Provisional application No. 61 / 786,965 is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]This invention relates to processes for forming polymeric foams and particularly to the manufacture of extruded polystyrene (XPS) foams in the absence of blowing agents that are known to deplete the ozone and increase the prevalence of global warming. This invention provides the use of a novel processing aid to stabalize the XPS foaming extrusion process and increase the operating window of XPS foam manufacturing.BACKGROUND[0003]The general procedure utilized in the preparation of extruded synthetic foam bodies generally includes the steps of melting a base polymeric composition, incorporating one or more blowing ag...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08J9/00C08J9/12
CPCC08J9/122C08J9/0009B29K2105/048B29K2025/06B29K2105/04C08J9/009C08J9/08C08J9/146C08J2201/03C08J2203/02C08J2203/06C08J2203/142C08J2203/162C08J2205/044C08J2205/046C08J2205/052C08J2205/10C08J2325/06B29C48/022B29C48/297B29B7/42B29B7/603B29B7/7409B29B7/94
Inventor HAN, XIANGMINBREINDEL, RAYMOND MARSHALLBRAMMER, S. THOMASDELAVIZ, YADOLLAHBOUDREAUX, CHASE J.FABIAN, BARBARAANNAN, NIKOI
Owner OWENS CORNING INTELLECTUAL CAPITAL LLC
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