Method for molding recycled EPS using powder adhesive and steam

Patent metadata

Field	Value
Publication number	US-9643343-B2
Application number	US-201414775273-A
Country	US
Kind code	B2
Filing date	Mar 11, 2014
Priority date	Mar 11, 2013
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

A method is provided of molding recycled EPS and other suitable expanded bead materials using a powder adhesive and steam. The method allows for molding EPS parts with over 5% and up to 100% recycled content. The method involves using an adhesive to fuse the regrind EPS particles under pressure from steam. The adhesive may be in powder form and preferably comprises small particles having a high surface area per unit weight and high static so the adhesive powder sticks to the surface of the regrind EPS particles during a dry blending step.

First claim

The invention claimed is:

1. A method of making a molded article comprising the steps of:
Step 100 : mixing about 95 wt % to about 99.9 wt % expanded bead foam regrind particles with about 0.1 wt % to about 5 wt % of a high static powder adhesive in a dry blend rotating mixer to obtain adhesive coated expanded bead foam regrind particles;
Step 102 : transferring the adhesive-coated expanded bead foam regrind particles to a mold;
Step 104 : bonding together the adhesive-coated regrind particles under pressure by introducing a small quantity of pressurized steam into the mold to raise the temperature above the melting point of the powder adhesive but below the melting point of the expanded foam regrind particles to create bonded regrind particles; and
Step 106 : cooling the bonded regrind particles in the mold for about two minutes, thereby producing a molded article.

2. The method of claim 1 wherein:
the expanded bead foam regrind particles are made of expanded polystyrene or expanded polyethylene.

3. The method of claim 1 wherein:
the expanded bead foam regrind particles are made of expanded polystyrene.

4. The method of claim 1 wherein:
the temperature in step 104 is about 60 C or higher.

5. The method of claim 1 wherein:
the temperature in step 104 is about 70 C or higher.

6. The method of claim 1 wherein:
the concentration of adhesive in step 100 is less than about 3.5 wt %.

7. The method of claim 1 wherein:
the adhesive in step 100 is a thermographic powder.

8. The method of claim 1 wherein:
before step 102 the adhesive-coated expanded bead foam regrind particles are mixed with virgin expanded beads.

9. The method of claim 8 wherein:
the adhesive-coated expanded bead foam regrind particles are mixed with virgin expanded beads in a ratio of at least 5 wt % expanded bead foam regrind particles to at most 95 wt % virgin expanded beads.

10. The method of claim 8 wherein:
the adhesive-coated expanded bead foam regrind particles are mixed with virgin expanded beads in a ratio of at least 10 wt % adhesive coated expanded bead foam regrind particles to at most 90 wt % virgin expanded beads.

11. The method of claim 8 wherein:
the adhesive-coated expanded bead foam regrind particles are mixed with virgin expanded beads in a ratio of at least 20 wt % adhesive coated expanded bead foam regrind particles to at most 80 wt % virgin expanded beads.

12. The method of claim 1 wherein:
during step 102 the adhesive-coated expanded bead foam regrind particles are transferred using air from an air-pressurized fill gun.

13. The method of claim 1 wherein:
the cooling step 106 lasts about two minutes.

14. The method of claim 1 wherein:
during the cooling step 106 water is circulated around the mold.

15. The method of claim 14 wherein:
after the cooling step 106 air is introduced into the mold to purge any remaining cooling water from the mold.

16. The method of claim 15 wherein:
after air is introduced into the mold a vacuum is pulled from areas of water circulation around the mold to further eliminate the water.

Assignees

• Sonoco Dev Inc

Inventors

• Ranade Ajit
• Piscopo Kate

Classifications

• B29K2105/048

  Expandable particles, beads or granules · CPC title

• C08J9/33

  Agglomerating foam fragments, e.g. waste foam · CPC title

• C08J9/236

  using binding agents · CPC title

• Y02W30/62

  Plastics recycling; Rubber recycling · CPC title

• C08J2323/06

  Polyethene · CPC title