Fluorinated HDPE barrier container

To determine the suitability of fluorinated HDPE containers as packaging material for the solvent-based formulations, the containers were placed in well-ventilated ovens at 50°C for 28 days. During this period the mass loss of the contents was monitored. To date more than 130 liquid crop protection chemical formulations have been evaluated at the AEC by this method with at least 91 of them having serious permeation problems through the untreated HDPE containers. In only two cases fluorinated containers did not have acceptable barrier properties. 

It has also been reported that some products with distinct flavors can be successfully contained in fluorinated container13-15 Work done at the AEC on the containment of concentrated flavorants in HDPE containers showed excellent containment for butter LR12390, aniseed oil, and dimethyl sulfide. The unacceptable barrier properties found for OR onion, OR garlic, and banana LR4186 led to a massive slump in popularity of one of the authors from colleagues who accused him of poisoning them ... 

The objective of this paper is to elucidate some of the processes that result in paneling, and the role of the AIROPAK Process in-line fluorinated barrier layer in preventing paneling in HDPE containers. 

The data in Figures 3 through 6 show that the onset of paneling in the untreated containers accompanies a 30% to 50% loss in tensile modulus and a 15% to 20% loss in tensile strength. It is evident that the presence of the in situ fluorinated barrier layer has served to preserve the mechanical properties of the underlying HDPE. 

The tensile modulus data of Figures 5 and 6 are replotted against the dynamic toluene sorption in Figures 8 and 9, respectively. In the case of the untreated HDPE containers, the loss of mechanical properties is a result of the significant solvent sorption by the polymer. The in situ fluorinated barrier reduces the solvent sorption in the HDPE and thus allows the material to retain its mechanical properties. 

The ability to package hydrocarbon solvents in HDPE containers is greatly improved by in situ fluorination using the AIROPAK Process. The barrier properties to toluene are improved 100-fold after fluorination. The propensity of an untreated HDPE container to panel in the presence of toluene is eliminated after fluorination. 

It was found that the paneling of untreated HDPE containers was induced by the combination of a decrease in the mechanical properties of the container wall and the concomitant development of a vacuum inside the container. Both of these effects were due to toluene sorption into the container wall. The application of an in situ fluorinated barrier to the interior of the container resulted in the preservation of the mechanical properties and pressure inside the container. 

Sulfonation can also be used to improve the barrier properties of HDPE bottles to hydrocarbons. After molding, the bottles are treated with sulfur trioxide in an inert gas, producing sulfonic acid groups on the bottle s surface, which are then neutralized with ammonia or sodium hydroxide. As with fluorination, proper procedures to ensure worker safety and avoid release of the sulfur trioxide and neutralization chemicals into the environment are necessary. Sulfonation also improves the adhesion of inks and coatings to the containers. 

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