Outdoor plastics

I’m trying to spec a plastic for the case of a 3.5" square consumer electronic device that could be sitting outside for years. It’s going to need:

  • UV resistance and colorfastness.
  • Not asking a lot of it mechanically, just need some snap features to make assembly toolfree and make a reasonably tight snap-fit seal without a gasket, and the usual stiffness that imparts solidity.
  • Transparent grades.
  • Recyclability would be nice.

I’m trying to get a feel for whether PET, HDPE or polypropylene works for this (assuming any of them will need a UV stabilizer). We’re low volume so saving on part costs and even the mold (can get away with softer steel, and bumpoffs for deeper undercuts) helps.

But even though HDPE, PP, etc is used for outdoor equipment, you don’t typically see them in electronics casings. Am I missing something? It was suggested to me that polycarbonate and ABS are preferred for flame retardation, but I haven’t seen any requirement like that for battery-powered devices.

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PC and ABS show up in things like deer cameras. Maybe a blend of those can impart fire retardant properties but like you said it might not be needed.
For the rest of the requirements I’d say PE like one of the fancy overpriced coolers. Gotta plan for shrink and warp but color and durability will be no problem.

I suggest looking into polydicyclopentadiene (pDCPD). Its an automotive thermoset for body panels that is recyclable.

First thing that came to mind was Bose’s outdoor speaker range. I believe they are quite popular, as the design is still being manufactured all these years later. It’s saying the cabinet is made of a glass-filled PP.

chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://assets.bose.com/content/dam/Bose_DAM/Web/pro/global/products/loudspeakers/FreeSpace_360P_Series_II/Downloads/Technical_data_sheet/Bose_FreeSpace_360P_TDS_20220111_LTR_EN.pdf

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That’s pretty cool. I wonder if there’s some acoustical dampening or deadening properties to GFPP too.

PVC, but not really recyclable. But will last a long time.
There is a pc-ABS blend that lends toughness to ABS and I know it can be used for electrical enclosures.

I used to work in the outdoor seating industry and have a little exposure to plastic types and specs. Here’s a couple things to look for that haven’t been mentioned above:

  • While most of the plastic we used was PE or PP due to manufacturing costs - the test all of our chairs had to go through was called a xenon arc test. if you start digging on google for plastics with a good rating on the test it might help point you in the right direction
  • The other thing to be aware of is color plays a significant role in the effectiveness of the color fastness and how quickly the plastic breaks down in the sun. Reds are particularly difficult. The basic rule of thumb we used was if you can think of a ten year old car with faded paint in that color - expect to have a tough time getting a long life out of it.

You mention itès for outdoor, but is it likely to be dropped? What about exposure to rain, sun screen, anything else?

Thanks all for the responses.

@Mr-914 Sure, it could be dropped, though not something that gets handled a lot (data logger) so it’s a nice-to-have. Integrity under years of outdoor exposure is the main thing. I can add UV stabilizers to pretty much anything.

@thecuster86 good insight on colorfastness. It’s going to be a canary yellow-orange color, but maybe stabilizers will help.

@KEGS I’ve used one of those PC/ABS blends, BayBlend. No complaints though it was a less stressful use case.

I probably am only considering PP or HDPE because I’m a sicko who wants to learn about a new material. The cost differences are not huge. Some combination of ABS and PC with additives is probably right for this. Though I won’t be able to use them due to shrink rate, I’ll try to get the molder to shoot in PP/HDPE as well just to get a feel for them for the future.

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Please come back with your findings, this will be good materials knowledge to share. Thanks.

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Did you consider aluminum? If you have radios, you can always do a hybrid aluminum extrusion with plastic end caps.

I don’t know if I mentioned it before, but there are accelerated UV tests that can be done once your plastic is selected. Also, you could ask a molder for dog bones, put them through testing and then test their mechanical properties. If you contact the big plastic makes, they may have more tests that they can share with you to validate your choice too.

Metal would be cool, but my design/price point doesn’t support that, especially if we gotta do plastic parts anyway.

I’ll definitely have some real-world data after doing this, but no time/money to do real UV testing, which is why I’m trying to find others’ experiences. Will be talking to my molder’s materials supplier, and the molder is cool with trying whatever plastics once we have tooling.

I suggest using ASA material, which is a kind of engineering plastics with good mechanical properties, workability, impact resistance and weather resistance. Manufacturers use its different performance characteristics to apply and replace other traditional materials:

  1. Excellent performance and light weight, replacing metal materials in auto parts, not only reducing costs, but also reducing car weight and increasing safety. After long-term outdoor use, it still has excellent impact resistance. Excellent resistance to ultraviolet radiation and weather, is used in the production of automobiles, motorcycles and other parts. Even if the wind, rain and sun are bad weather, it will not fade.
  2. Good weather resistance, strong aging resistance, so it is also widely used in the electronic and electrical industry. Because it is superior to ABS resin in terms of anti-ultraviolet linearity and weather resistance, the product color is more durable, and it has become a “substitute” for ABS in the field of electronic and electrical enclosures.
    3.ASA material has become the main material in the fields of horticultural irrigators, lawn mowers and sports equipment due to its aging resistance, oil resistance and color stability.
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