Process for making alkenyl aromatic foam packing bodies with carbon dioxide and/or ethane blowing agent systems

A process for making discrete, closed-cell, alkenyl aromatic polymer foam packing bodies, comprising:

• a) heating an alkenyl aromatic polymer material comprising greater than 50 percent by weight alkenyl aromatic monomeric units to form a melt polymer material;
• b) forming a foamable gel by incorporating into the melt polymer material at an elevated pressure a blowing agent having about 20 weight percent or more based upon the total weight of the blowing agent of a first blowing agent selected from the group consisting of carbon dioxide, ethane, and a mixture of the foregoing;
• c) extruding the foamable gel through a die to form an essentially continuous strand of the foamable gel;
• d) pelletizing the foamable gel strand to form a plurality of discrete gel strands;
• e) allowing the plurality of the discrete gel strands to expand in a region of reduced pressure to form a plurality of the discrete foam bodies;
• and
• f) further expanding the foam bodies by exposing them one or more times to heated air or steam.

A process for making an article formed of discrete, closed-cell, alkenyl aromatic polymer foam packing bodies, comprising:

• a) heating an alkenyl aromatic polymer material comprising greater than 50 percent by weight alkenyl aromatic monomeric units to form a melt polymer material;
• b) forming a foamable gel by incorporating into the melt polymer material at an elevated pressure a blowing agent having about 20 weight percent or more based upon the total weight of the blowing agent of a first blowing agent selected from the group consisting of carbon dioxide, ethane, and a mixture of the foregoing;
• c) extruding the foamable gel through a die to a region of reduced pressure to form an alkenyl aromatic polymer foam strand;
• d) pelletizing the foam strand to form a plurality of the discrete foam bodies;
• e) further expanding the foam bodies by exposing them one or more times to heated air or steam;
• and
• f) molding and coalescing the foam bodies to form an article.

A process for making discrete, closed-cell, alkenyl aromatic polymer foam strands, comprising:

• a) heating an alkenyl aromatic polymer material comprising greater than 50 percent by weight alkenyl aromatic monomeric units to form a melt polymer material;
• b) forming a foamable gel by incorporating into the melt polymer material at an elevated pressure a blowing agent having about 20 weight percent or more based upon the total weight of the blowing agent of a first blowing agent selected from the group consisting of carbon dioxide, ethane, and a mixture of the foregoing;
• c) extruding the foamable gel through a die to a region of reduced pressure to form an essentially continuous foam strand;
• d) further expanding the continuous foam strand by exposing it to heated air or steam;
• and
• e) intermittently severing the continuous foam strand to form a plurality of discrete foam strands.

A process for making discrete, closed-cell, alkenyl aromatic polymer foam strands, comprising:

• a) heating an alkenyl aromatic polymer material comprising greater than 50 percent by weight alkenyl aromatic monomeric units to form a melt polymer material;
• b) forming a foamable gel by incorporating into the melt polymer material at an elevated pressure a blowing agent having about 20 weight percent or more based upon the total weight of the blowing agent of a first blowing agent selected from the group consisting of carbon dioxide, ethane, and a mixture of the foregoing;
• c) extruding the foamable gel through a die to a region of reduced pressure to form an essentially continuous foam strand;
• d) intermittently severing the continuous foam strand to form a plurality of discrete foam strands;
• and
• e) further expanding the discrete foam strands by exposing them one or more times to heated air or steam.