I was walking through a local store the other day when I came across a new line of Rubbermaid food storage containers that intrigued me. What caught my eye was the fact that these containers are crystal clear. They can’t be made of polycarbonate, which is a big no-no for food storage containers because of BPA. The recycling code on the container is #7 which is “other”. Polycarbonate would fall under the 7 recycling code also but so would many other materials. What is this material?
I had to buy one to find out.
I have previously written about the fact that the FDA considers BPA containing plastics to be safe for food and water contact. In my opinion, the science supports the claim that it is safe. However, I have also written that no one should consider using polycarbonate for food or water contact applications because public opinion has turned against it. Regardless of the science the public is not going to buy it if it does not say “BPA Free” somewhere on the packaging.
So, back to the Rubbermaid Brilliance® container; a little testing revealed that it is made out of a copolyester material (I hate to be wasteful but I had to sacrifice the container in order to test it). A little research online revealed that these containers are made from a copolyester material made by Eastman and sold under the trade name Tritan®. The gasket is overmolded onto the container and is made out of some type of Styrene Butadiene (pronounced BYOO-TUH-DAHY’-EEN) Copolymer.
The container actually feels like polycarbonate and seems to be pretty tough. Looking at several data sheets from Eastman, this material has as much impact strength as polycarbonate and as much elongation as well. The biggest problem with copolyester materials has been heat resistance which might cause issues after repeated dishwasher use but Eastman has found a way to improve the heat resistance quite a bit. Also, copolyester has significantly better chemical resistance than polycarbonate.
Essentially this material is a copolymer of the polyester material known as polyethylene terephthalate (PET). Eastman is using a proprietary comonomer that dramatically improves the heat resistance and impact strength of PET.
As far as health concerns, there does not seem to be a lot of issues with copolyester. There have been a couple of studies that have suggested that even though copolyester does not contain any BPA that it still might contain some chemicals that mimic estrogen or show estrogenic activity (EA). There was a legal battle between a company called Plastipure and Eastman regarding some of the claims that Eastman was making about the safety of Tritan. Eastman won the legal battle for what it’s worth.
A search of a number of anti-plastics websites reveals that a few are expressing concerns about copolyester but most sites don’t even mention it. Also, the recycling code on a copolyester container is #7 which puts it into the “other” category making it more difficult to determine what it’s made from.
The fact that there is some negative information out there about copolyester would warrant some caution in using it for an application. Polyethylene and polypropylene are still the safest bets but if you absolutely need a crystal clear container, this is the best option and is an excellent replacement for polycarbonate.
It should be noted that the FDA considers copolyester safe for use in food and water contact applications. However, the FDA considers polycarbonate safe as well. The public does not however and thus polycarbonate water bottles and food storage containers have disappeared from store shelves.
Whether the public turns against it really depends on the studies that come out and how the media reports on it. Although Eastman’s Tritan was developed in the early 2000s, it has only been in wide spread use for the last 5 or 6 years. So far so good.
The material offers some processing advantages over polycarbonate which could help reduce costs as well. I was unable to find any information regarding how much Eastman’s Tritan material costs in relation to polycarbonate. If anyone is currently buying this stuff, I would appreciate you leaving a comment regarding pricing.
If you are interested in getting a quote on this material it looks like there are a number of distributors including Nexeo and PolyOne that carry it.