Food Grade Urethane.

[gilberts]

I just found that there is a food grade urethane (PU4 An acrylated poly-ester-urethane consisting of polyadipate (neopentylglycol/adipic acid) as polyol reacted with 4-4' methylenedicyclohexyl diisocyanate.)
I now plan on making the chamber of a food carrier with this material. My question: Can we still control the density? Would a low density be better for heat retention? Is making urethane food grade more expensive?
I am going that road because of the low cost molding versus injection.
Thank you.

 

[Pressed]

Less dense or more air should insulate better. The cost is usually higher for material that uses a special process and doesn't sell in high quantities.

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[pkruchoski]

gilberts,
PU4 MDI polyurethanes are very expensive compared to thermoplastics (injected molded plastics) The liner I think you are requiring would have to be a solid liner and have a density of .035-.040 lb/in^3. These have a duro shore A, of 70-90 give or take. Also most urethanes will start to break down with heat and water around 140 deg F or less. There are some that will take boiling water.

http://www.irproducts.com/products/iracore.html

The solid MDI polyurethanes have a typical insulation K factor of .2 (BTU*in*F I can't remember the units)