EXPANDED POLYPROPYLENE FOAM TRAY

1 . A method for forming a foamable polypropylene extrusion mixture, comprising:

providing a polypropylene resin;

heating the polypropylene resin and blending a nucleating agent into the polypropylene resin;

blending a polymer stabilizer into the polypropylene resin;

blending a physical blowing agent into the polypropylene resin;

wherein the foamable polypropylene extrusion mixture is configured to produce a foam article having a maximum compressive load which is greater than or equal to 15 N and less than or equal to 100 N; and

wherein a total amount of ethylene-derived polymer content in the extrusion mixture is less than or equal to 3% by weight.

2 . The method of claim 1 , wherein the polypropylene resin is selected from the group consisting of a virgin polypropylene homopolymer resin and a recycled polypropylene homopolymer resin.

3 . The method of claim 1 , wherein the foamable polypropylene extrusion mixture comprises from 70% to 95% of the polypropylene resin.

4 . The method of claim 1 , wherein the polypropylene resin has a melt flow index (MFI), measured at 230° C. and 2.16 kg according to ISO 1133, of between 1 g/10 min and 20 g/10 min.

5 . The method of claim 1 , wherein the nucleating agent comprises talc.

6 . The method of claim 5 , wherein the talc is added to the foamable polypropylene extrusion mixture in a talc masterbatch composition comprising talc particles dispersed in a carrier resin.

7 . The method of claim 6 , further comprising one or both of:

wherein the carrier resin comprises a polyolefin resin and the talc masterbatch composition comprises 40-80% talc by weight; and

wherein the talc masterbatch composition is added to the foamable polypropylene extrusion mixture in an amount that yields a weight percentage of talc in the foam sheet in the range of 2% to 6%.

8 . (canceled)

9 . The method of claim 1 , wherein the polymer stabilizer is selected from the group consisting of: an antioxidant; an antioxidant masterbatch composition comprising the antioxidant dispersed in a carrier resin; and an antioxidant masterbatch composition added to the foamable polypropylene extrusion mixture in an amount ranging from 0.9-1.0% by weight.

10 . (canceled)

11 . (canceled)

12 . The method of claim 9 , wherein the antioxidant masterbatch composition is added to the foamable polypropylene extrusion mixture in an amount that yields a concentration of the antioxidant in the foam article of about 1000 ppm by weight.

13 . The method of claim 9 , wherein the antioxidant is selected from the group consisting of pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) and tris(2,4-di-tert-butylphenyl) phosphite and wherein the carrier resin is an extrusion grade polypropylene resin.

14 . The method of claim 1 , wherein the physical blowing agent is selected from the group consisting of isobutane; isopentane; carbon dioxide; isobutane, isopentane, or a combination thereof in an amount ranging from about 2.5% to about 5% by weight; carbon dioxide in an amount ranging from 0% to about 1% by weight; and any combination of the foregoing.

15 . (canceled)

16 . The foamable polypropylene extrusion mixture produced by the method of claim 1 .

17 . A product produced from the foamable polypropylene extrusion mixture of claim 16 , wherein the product is selected from the group consisting of:

a foam sheet; and

a thermoformed foam tray.

18 . (canceled)

19 . The product of claim 17 , wherein the product is a thermoformed foam tray having a maximum compressive load in a range of about 15 N to about 60 N and a density in a range of about 70 kg/m 3 to about 200 kg/m 3 .

20 . (canceled)

21 . The method of claim 1 , further comprising:

blending a chemical foaming agent into the polypropylene resin.

22 . The method of claim 21 , wherein the chemical foaming agent is added to the foamable polypropylene extrusion mixture in a chemical foaming agent masterbatch formulation comprising an endothermic chemical foaming agent dispersed in a carrier resin.

23 . The method of claim 21 , wherein the carrier resin comprises a polyolefin resin and wherein the chemical foaming agent masterbatch composition comprises about 20% to about 60% by weight of one or more active endothermic chemical foaming agents.

24 . The method of claim 23 , wherein the chemical foaming agent masterbatch composition is added to the foamable polypropylene extrusion mixture in an amount ranging from about 1% to about 2% by weight.

25 . The method of claim 1 , further comprising:

extruding the foamable polypropylene extrusion mixture using an extruder to form a foam web;

thermoforming one or more foam trays from the foam web; and

cutting the foam web to separate the one or more foam trays from the foam web.

26 . A foamable polypropylene extrusion mixture, comprising:

a polypropylene resin;

a nucleating agent;

a polymer stabilizer; and

a physical blowing agent;

wherein the foamable polypropylene extrusion mixture is configured to produce a foam article having a maximum compressive load which is greater than or equal to 15 N and less than or equal to 100 N; and

wherein a total amount of ethylene-derived polymer content in the extrusion mixture is less than or equal to 3% by weight.

27 . A method for forming a polypropylene foam tray, comprising:

providing a foamable polypropylene extrusion mixture, the foamable polypropylene extrusion mixture comprising:

a polypropylene resin;

a nucleating agent;

a polymer stabilizer; and

a physical blowing agent;

extruding the foamable polypropylene extrusion mixture to form a foam web;

thermoforming the foam web to form one or more foam trays; and

cutting the one or more foam trays from the foam web;

wherein the foam tray has a maximum compressive load which is greater than or equal to 15 N and less than or equal to 100 N; and

wherein a total amount of ethylene-derived polymer content in the extrusion mixture is less than or equal to 3% by weight.

28 . The method of claim 27 , wherein the foam web has a thickness in the range of from about 90 mil to about 180 mil.

29 . (canceled)