Liquid Solar Pool Cover Ingredients

Jun 10, 2010
11
Southern, CA
#1
Anyone using the newer Natural Chemistry Cover Free?

I found the ingredients (stearyl alcohol, propylene glycol) here: https://media.nat.cm/filer_public/3a/c4 ... _aug14.pdf

I also found a fascinating, though over my head patent here: http://patentscope.wipo.int/search/en/d ... escription

Light reading for Chemgeek!

They detail dozens of water soluble/insoluble mixtures.
They use stearyl alcohol for insoluble, but I didn't see mention of propylene glycol as the soluble (polymer) in any of their tests.

Maybe someone an decipher the new literature and tell us a better cocktail than the 4.6% each stearyl/cetyl alcohol we've come to expect

This maybe Coverfree patent (ingredients match): http://www.google.com/patents/US3888995
Propylene glycol may be used as the dispersant.
It is a component of Corexit which was used to disperse oil after the Gulf oil spill.

Another patent loaded with TONS of references.
http://www.google.com/patents/US7867412t*
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#3
I got the links from this post and the subsequent one:

Natural Chemistry® COVERfree™ MSDS that lists 3-7% 1-Octadecanol (stearyl alcohol).

Patent application WO2010071931 describes using a combination of a water soluble chemical with a water insoluble chemical that hydrogen bond with each other. This presumably stabilizes the water insoluble monolayer that otherwise gets easily disrupted by wind. Many different possible combinations of chemicals are mentioned, but the ones that were tested with data are the following:
poly(acrylic acid) and ethylene glycol monostearyl ether
poly(acrylic acid) and stearyl alcohol
poly(acrylamide-co-acrylic acid) and ethylene glycol monostearyl ether
poly(acrylic acid) and stearyl diethylene glycol monomethyl ether
poly(acrylic acid) and ethylene glycol monostearyl ether
ethylene glycol monostearyl ether and carbonyl polymers
cetyl alcohol and polyvinyl pyrrolidone
polyether polymer and ethylene glycol monostearyl ether
polyvinyl alcohol and ethylene glycol monostearyl ether
poly(ethylene-alt-maleic anhydride) and ethylene glycol monostearyl ether
poly(acrylamide-co-acrylic acid) and ethylene glycol monostearyl ether
non-carbonyl polymers and fatty alcohols
polyvinyl pyrrolidone-co-methyl acrylate) and a mixture of fatty alcohols
a mixture of polymers and a blend of fatty alcohols
polyvinyl alcohol and a mixture of fatty alcohols

U.S. Patent 3888995 discloses the following preferred embodiment:
By way of referring to a preferred composition as an example, cetyl alcohol, stearyl alcohol, behenyl alcohol, stearic acid, polyethylene glycol and 1,2,6- hexanetriol can be mixed with stirring to about -85C; propylene glycol can be heated to -95C with stirring (a medicant stable at this temperature could be added to either phase during this step); and the two liquids can be mixed with stirring. Good agitation is provided until the mixture cools to room temperature.
U.S. Patent 7867412 refers to a lot of other earlier patents that are good references and then discloses a preferred embodiment with Polyoxyethylene (2) laurel ether at 0.5 to 50% by weight with additional viscosifier and preservative. The main advantage of this product is that it avoids use of a flammable carrier (e.g. isopropyl alcohol).

You can look at a long discussion on another forum here where you also just posted that references U.S. patent 6303133 which appears to be the original one for HeatSavr that uses cetyl alcohol as its primary ingredient along with isopropyl alcohol as a carrier that evaporates and some calcium hydroxide is used as a dispersant. The WaterSavr and Natural Chemistry COVERfree products use stearyl alcohol with 18 carbons compared to cetyl alcohol with 16. There is a claim that one of the solar fish products used Polyoxyethylene (2) lauryl ether as described in U.S. Patent 7867412 referenced above.

So to sum up, there are three basic approaches:

  1. Use a fatty alcohol such as cetyl alcohol or stearyl alcohol along with a carrier such as isopropyl alcohol and a dispersant such as calcium hydroxide
  2. Use a combination of a water soluble poly(acrylic acid) with a water insoluble stearyl alcohol
  3. Use Polyoxyethylene (2) laurel ether
Keep in mind that you could be infringing the associated patent if you make these products and use them, even if you do not sell them. In practice, though, making them for personal use will have such little individual economic harm that it's unlikely you will get sued, but technically the patent owner/assignee could sue and get an injunction against your use of it (again, highly unlikely, but legally possible). At a minimum, you would be depriving the rightful recovery of R&D costs to the inventor (or company assigned the patent) of the product. Is it really worth your trying to replicate making one of these products?
 
Jun 10, 2010
11
Southern, CA
#4
Thanks for fixing my URLs and the quick expert analysis.

I'm surprised that the references use ethylene glycol (which I thought was poisonous) considering I think their work is intended for reservoirs etc.

Maybe that's why the one msds references propolyene glycol?

And thanks for reminding us that these are patented.
I'm not planning to sell any, just trying to understand the mechanisms and decide which "works" best.

I find heatsavr very effective, but only lasts a day and gets waxy fibrous stuff in my skimmer sock.

I tried cover free and it got snot like stuff in the skimmer sock.
Now it's supposed to last more than a day, but I'm not sure...

Anyone using cover free?
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#5
Ethylene glycol is not as toxic as you might imagine. The LD[sub]50[/sub] for acute oral toxicity in rats is 4700 mg/kg (table salt is more toxic at 3000 mg/kg). The amount ingested that is considered to be toxic enough to require medical treatment is 0.1 ml/kg so roughly 100 mg/kg. The main risk is that it is sweet tasting so that children who find it (in concentrated form) could drink it.

So dispersed in a pool and then evaporated it's not an issue, but if someone were to pierce the container containing concentrate or it were to otherwise leak, then direct ingestion would be a problem. For reservoirs, I presume they expect the dilution and evaporation to prevent it being a problem, but since there are non-toxic alternatives there isn't much reason to use it instead of propolyene glycol or isopropyl alcohol.

As for COVERfree vs. HeatSavr, I'd expect them to behave fairly similarly since the former uses stearyl alcohol with 18 carbons while the latter uses cetyl alcohol with 16 carbons. You pretty much found that to be the case in terms of not lasting that long and getting accumulation in your skimmer sock. It's expected for skimmer socks and especially scum balls to collect insoluble organics from the water. Any of these systems would probably have that problem.