Looking for a paint system/UV material(s) to paint over molded HDPE material for outdoor application.  Please help!

You can get HDPE compounded in a pretty good selection of colors, but it's basically not paintable.   

Mike Halloran
Pembroke Pines, FL, USA

Mike,

Thanks!  We just want to add some custom colors with 'shading' effect onto our products.  Plus, we're ready to energize the molded surface so we can paint it.  

ew

You might try adding a couple of percent maleated PE to give some polarity. A friend tried that concept in an ABS system and it improved adhesion ten fold.

As you said, oxidation by corona, flame or plasma would work too.

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
Instant Downloads & Inexpensive
www.plastictraining.com

Dr.  DeArmitt

Thanks!  How about how to start a paint line?

What kind of paints and equipment should we go after?

ew

BTW, I have another non-paint related question posted: CaCO3.  Could you please advise me on that one as well?

Painting can be done but is difficult. The addition of a second component to help paint stick as Chris suggests is a good one.

The successful history is with automotive bumpers in PP. They only performed in a barely acceptable manner with corona discharge, but as time went on, the alloys where developed and the problems of dimensional stability, impact strength and paint adhesion all improved a lot.   

Regards
Pat
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I know nothing about specific paints to use.  Sorry.

Chris DeArmitt - PhD FRSC CChem
Plastic & Additives Webinars
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Akzo who I think is Sikkens and Bayer are both big in paints for plastics. Their tech support should help with primer selection. Once again automotive bumper practices should be a good starting point.

Regards
Pat
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If, like me, you have no personal experience with painting polyolefins in production, I suspect you might be underestimating the cost of the learning curve you face.

I remember a flurry of publicity maybe a decade ago about selecting a finish process for John Deere lawn tractor hoods/boots.

I think at that time they were very enthused about in-mold finishing, either with film or paint sprayed into the cavity. ... or I may be remembering something else.

Regardless, I examined an actual production part at a home supply store last week. The current part is injection molded in a custom color, that lovely JD green that clashes with everything including itself, not pre- or post- finished. The exterior surface was quite nice. The interior surface includes a recycling material designation, "PC-ASA", which doesn't ring a bell for me; maybe someone else can guess what polymer/alloy that suggests.

Mike Halloran
Pembroke Pines, FL, USA

Its a polycarbonate ASA alloy. ASA (Acrylonitrile Styrene Acrylate) is virtually ABS with the inherently unstable to UV light butadiene replaced with the much more stable to UV light Acrylate rubber.

Regards
Pat
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Polyolefins like HDPE are very difficult to paint as stated by others. For automobiles, the painting of these parts is enabled by the use of a chlorinated polyolefin primer. The large paint manufacturers like PPG, BASF and DuPont can provide this to you.