Places to Find Information on Flame Treating of Plastics

[srennekamp]

Does anyone know of a good place to find detailed technical information on the flame treating of plastics, specifically Polypropylene, to accept coatings? I am looking into it for a project of mine, but I really don't know anything about it.

 

[gibson55]

Just joined and saw your entry in March on flame treatment of plastics. We call this "corona treatment" and it is used to functionalize the surface of a polyolefin such as your polypropylene. Unfortunately, in practical terms it has had limited success largely due to inexperience of the applicator and a general lack of understanding of the dynamics at play to achieve a successful application.

We worked with this situation many years ago while attempting to bong liquid epoxy coatings to both polypropylene and polyethylene. We weren't successful on the long term using the corona process and subsequently learnt that "corona treatment" is a reversible process over time.

We have been very successful by using other surface treatments that have resulted in producing permanent non-reversable chemical bonds between the olefin substrate and the thermoset polymer topcoat.

Regards, gibson55

 

[btrueblood]

Gibson,

Can you elaborate on the process you use, or is it a proprietary treatment? If proprietary, I think a website link could be appropriate.

 

[Compositepro]

Flame treating and corona treatment are not the same thing although they are often used for the same purpose, i.e., to increase the surface energy of polymer surfaces for better wettability and/or bonding. Corona is more controllable but is often more expensive to istall.

 

[gibson55]

BTRUEBLOOD

(1) There is a family of grafted polymers available which are manufactured in powder form, particle size averaging 7 microns. The delivery system for these powders incorporates a compressed air stream which drives the powders through a live flame (in which the powder particles are melted)then onto the chosen surface.

In the case of a polyethylene, polypropylene or polyester surface the delivered, melted particles land on a pre heated heated surface where they chemically attach then bond when allowed to cool.

In most cases the resulting, newly coated surface offers the same or better performance properties when compared to a liquid epoxy or polyurethane coating.

Your intuition is correct. We do hold 4 patents on this type of coating process in particular in situations where pipelines are the structures in question. However our patents do apply to any metal or non-metal surface.

SRENNKAMP

(1) It has been our experience that corona treatment of polyolefins will permit the treated surface to accept "coatings" by which I assume you mean liquid or powder coatings. However, for our purposes the liquid coating properties, specificially the poor flexibility of the dry film, tends to conflict with the more flexible substrate and ends up exhibiting cracking and 'spalling' of the liquid topcoat thereby defeating the intended purpose of the application.

(2) Treating the olefin surface with fluorine gas is now the accepted norm to achieve what you are looking for - a permanent, chemical bond for a coating to a plastic. I can't go into it any further without compromising our commercial opportunities but we would certainly be interested in learning what you are attempting in more detail or you can attempt to reach me by some method that should not compromise the integrity of this forum. perhaps, as BTRUEBLOOD has suggested you can visit a site entitled: 4pipelines.com to gain further information.

gibson55