Insulated foam materials

[gemmap]

We're currently trying to source a material to be used as an insulating jacket for a bottle (this is for a major global client)

Material Requirements:
1.1 Primarily, an insulation effect - to keep the bottled liquid cool or warm.

1.2 Must not degrade over time, through repeated microwaving / dishwashing

1.3 FDA approved

1.4 Wall thickness - dependant on material properties. But ideally 5mm max.

1.5 Translucency - being able to view the liquid level through the material would be a benefit.

1.6 An Injection mouldable material is preferable.

1.7 Ideally, the material would be soft & 'squidgy' to aid grip ,and have a little flexibility to enable the bottle neck to snap in.


If you can get back to me with any suggestions/product samples etc. that may help I would be very grateful.

 

[patprimmer]

Polyurethane sounds like the best prospect to me, that is if you can get an FDA grade.

Does it really need to be FDA as I presume it will not contact the food directly.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[btrueblood]

I've seen and used a variety of foamed polymers over the years, including polyethylene and polyproylene, EPDM, polyurethane, polystyrene, latex or natural rubber. All of these are capable of being molded by one means or another. You may want to talk to Phillips corp, as it sounds like you want an over-mold or two-shot process to bond the insulation to the bottle?

Foaming a polymer usually involves addition of a blowing agent, which can affect the properties of the polymer, so picking the right blowing agent can be tricky. This will limit your supplier base, since some/many injection molders don't know about blowing agents. How well the material insulates will depend on how light the foam gets (more blowing = more bubbles = thinner bubble walls = better insulator), but there are limits with each of the above polymers to how light a foam can get before you get settling/segregation effects and non-uniform foam density.

 

[amorrison]

I would like to change your thinking . . .

For thermal resistance conversion to metric
(Imperial R20=RSI 3.5 Metric)

1. At typical room temperatures the
still air film has a R=0.68
2. Five mm of "good" foam (extruded polystyrene) will
have a R of R=1.0
3. Total R with foam = 1.68 or a 2.5X in R value

4. If you went to a clear plastic covering with a 0.5 inch (13mm) air space between the plastic and the bottle
the R will be 1.2 (assuming emissivity =0.5) so total R = 1.88 . The covering could be spaced out from the bottle by "pins" that are part of the plastic part.

Check out ASHRAE Fundamentals -Design Heat Transmission Coefficients

 

[amorrison]

Post also to

Heat Transfer & Thermodynamics engineering forum