Back-diffusion quality control method for barrier treated containers
AssigneeAir Products and Chemicals, Inc.
InventorThomas E. McWhorter
Life of this patent
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Abstract
A process is provided for making a distinction between solid, porous materials, e.g. thermoplastics, having surfaces which are either untreated or treated to render them measurably impermeable to volatiles. The surfaces are first exposed to a high concentration of a volatile fluid which is removed after a fixed time period. The surfaces are then exposed to an environment, e.g. a vacuum, to cause the volatile fluid to back-diffuse and the fluid that back-diffuses is measured. The rate at which the fluid back-diffuses from the untreated surface is considerably greater than that of the treated surface.
Claims10
A method for distinguishing between a solid material having at least one surface treated to impart a measurable degree of impermeability to a volatile fluid and an untreated material which comprises the steps of:
- (a) exposing the treated surface to a high concentration of said volatile fluid for a fixed period of time,
- (b) removing the excess fluid from said treated surface after said fixed period of time,
- (c) exposing said treated surface from step (b) to an environment for causing volatile fluid to back-diffuse through said treated surface into the environment;
- and
- (d) measuring if the concentration of said volatile fluid back-diffusing into the environment from said treated surface after a fixed period of time is at least one order of magnitude less than the concentration of such a fluid back-diffusing from said untreated material.
A method for distinguishing between a barrier treated surface and an untreated surface of solid materials which comprises the steps of:
- (a) contacting for a fixed period of time each of the treated and untreated surfaces with a high concentration of a volatile fluid to diffuse through the untreated surface into the interior of said solid material at a more rapid rate than through the treated surface;
- (b) ceasing step (a) after said fixed period of time;
- (c) contacting each of the surfaces with a high velocity of an inert gas to rapidly dry each of said surfaces;
- (d) reducing the velocity of said inert gas and contacting each of said surfaces for a back-diffusion time in the range of about 30 seconds to 30 minutes;
- (e) measuring and comparing the concentration of said volatile fluid that back-diffuses into said inert gas after it has contacted each of said surfaces;
- and
- (f) distinguishing said treated from said untreated surface which back-diffuses at a greater rate than said treated surfaces.
Dependencies are inferred from the claim text.