Gas-impermeable, chemically inert container structure for food and volatile substances and the method and apparatus producing the same

Abstract

A method of making a gas-impermeable, chemically inert container wall structure comprising the steps of providing a base layer of an organic polymeric material; conducting a pair of reactive gases to the surface of the base layer preferably by pulsed gas injection; heating the gases preferably by microwave energy pulses sufficiently to create a plasma which causes chemical reaction of the gases to form an inorganic vapor compound which becomes deposited on the surface, and continuing the conducting and heating until the compound vapor deposit on the surface forms a gas-impermeable, chemically inert barrier layer of the desired thickness on the surface. Various wall structures and apparatus for making them are also disclosed.

1 . A method of making a gas-impermeable container wall structure comprising the steps of 
 providing a base layer of an organic polymeric material;    conducting a plurality of reactive gases to the surface of the base layer;    heating the gases sufficiently to create a plasma which causes the chemical reaction of said gases to form an inorganic vapor compound which becomes deposited on said surface, and    continuing the conducting and heating steps until the vapor compound deposit on said surface forms a gas-impermeable, chemically inert barrier layer of the desired thickness on said surface.    
     
     
         2 . The method defined in  claim 1  wherein the heating step is accomplished by exposing said gases and said surface to microwave radiation.  
     
     
         3 . The method defined in  claim 2  including 
 pulsing the conducting and exposing steps at a selected frequency to control the temperature and stoichiometry of the deposited vapor compound.  
 
     
     
         4 . The method defined in  claim 1  including the additional step of, prior to the conducting step, flowing an inert gas to said surface and ionizing the inert gas to subject said surface to ionic bombardment in order to clean said surface and render it receptive to said vapor compound.  
     
     
         5 . The method defined in  claim 4  including the additional step of depositing a plasticizer on said surface during said ionic bombardment so that the molecules of the plasticizer become crosslinked and form a coherent skin on said surface.  
     
     
         6 . The method defined in  claim 1  including the step of forming the base layer into a container before the conducting step.  
     
     
         7 . The method defined in  claim 1  including the step of forming said structure into a container after the continuing step.  
     
     
         8 . The method defined in  claim 1  wherein the providing step includes providing a base layer containing a dispersal of tiny radiation blocking particles of an inorganic semiconductor material which prevents the transmission through said wall structure of selected electromagnetic radiation frequencies.  
     
     
         9 . The method defined in  claim 1  including the step of covering said barrier layer with a relatively thin top layer of a hard, abrasion-resistant material.  
     
     
         10 . The method defined in  claim 1  including the steps of 
 forming said barrier layer of a material selected from the group consisting of crystalline silicon, amorphous silicon and hydrogenated amorphous silicon, and  
 controlling the thickness of said barrier layer so that said barrier layer blocks electromagnetic radiation below a selected cutoff wavelength.  
 
     
     
         11 . A method of making a gas-impermeable container wall structure comprising the steps of 
 providing a container of an organic polymeric dielectric material;    creating a relatively high vacuum in the container;    injecting a plurality of inorganic reactive gases into said container;    exposing the container and its contents to microwave energy sufficient to ionize said gases and produce a plasma in the container which causes chemical reaction of said gases thereby forming an inorganic vapor compound which becomes deposited on the interior wall of the container, and    continuing the injecting and exposing steps until the compound vapor deposit on said interior wall forms a gas-impermeable, chemically inert barrier layer of a selected thickness on said interior wall.    
     
     
         12 . The method defined in  claim 11  wherein, prior to the injecting step, flowing an inert gas into the container in the presence of microwave radiation so as to ionize the inert gas whereupon the gas ions impact and clean the interior wall and render it receptive to said vapor compound deposit.  
     
     
         13 . The method defined in  claim 11  including the additional steps of 
 injecting said plurality of gases into the container as injection pulses of a selected frequency, and  
 exposing the container and its contents to microwave energy as energy pulses having said selected frequency.  
 
     
     
         14 . The method defined in  claim 11  including the steps of 
 forming said barrier layer of a material selected from the group consisting of crystalline silicon, amorphous silicon and hydrogenated amorphous silicon, and  
 controlling the thickness of said barrier layer so that said barrier layer blocks electromagnetic radiation below a selected cutoff wavelength.  
 
     
     
         15 . A gas-impermeable container wall structure comprising 
 a base layer of an organic polymeric material, and 
 a gas-impermeable chemically inert barrier layer on said base layer formed by conducting a plurality of reactive gases to the surface of the base layer, heating the gases sufficiently to create a plasma which causes the chemical reaction of said gases to form an inorganic vapor compound which becomes deposited on said surface, and continuing the conducting and heating steps until the vapor compound deposit on said surface reaches a desired thickness.  
   
     
     
         16 . The wall structure defined in  claim 15  and further including a crosslinked plasticizer between said surface and said barrier layer.  
     
     
         17 . The wall structure defined in  claim 15  and further including a dispersal in said base layer of tiny radiation blocking particles of an inorganic semiconductor material which prevents the transmission through said wall structure of selected electromagnetic radiation frequencies.  
     
     
         18 . The wall structure defined in  claim 15  and further including a relatively thin top layer of a hard, abrasion-resistant material covering said barrier layer.  
     
     
         19 . The wall structure defined in  claim 15  wherein said barrier layer is of a material selected from the group consisting of silicon dioxide, silicon nitride, aluminum oxide and boron nitride.  
     
     
         20 . The wall structure defined in  claim 15  wherein 
 said barrier layer is of a material selected from the group consisting of crystalline silicon, amorphous silicon and hydrogenated amorphous silicon, and  
 said barrier layer is of a thickness to block electromagnetic radiation below a selected cutoff wavelength.  
 
     
     
         21 . The wall structure defined in  claim 15  wherein said barrier layer is selected from the group consisting of silicon dioxide, silicon nitride and boron nitride.  
     
     
         22 . A gas impermeable container wall structure comprising a base layer of an organic polymeric material, and 
 a gas impermeable, chemically inert barrier layer on said base layer, said barrier layer including 
 a carrier material having a refractive index; and  
   dispersed therein, a silicon particulate material having substantially uniform particle size and exhibiting an absorption cross-section greater than 1 below a predetermined cut off point, the material having a refractive index differing from that of the carrier and being present in sufficient density per unit of surface area to substantially block passage of radiation below the predetermined cut off point.    
     
     
         23 . The material of  claim 22  wherein the particulate material is spherical and exhibits an imaginary refractive-index component K which decreases substantially with wavelength.  
     
     
         24 . The material of  claim 23  wherein K is at least 0.5 at a wavelength of 0.4 μm and is less than 0.005 μm at a wavelength of 0.7 μm.  
     
     
         25 . The material of  claim 23  wherein the density per unit of surface area varies inversely with K.  
     
     
         26 . The material of  claim 22  wherein the particle size is chosen to minimize scattering of visible radiation.  
     
     
         27 . The material of  claim 22  wherein the particulate material consists of uniformly sized spheres having a diameter that ranges from 0.005 μm to 0.04 μm.  
     
     
         28 . The material of  claim 22  wherein the particulate material consists of spheres of diameter less than 0.04 μm.  
     
     
         29 . The material of  claim 22  wherein the density per unit of surface area is approximately 10 −4  to 10 −5  g/cm 2 .  
     
     
         30 . The material of  claim 22  wherein the silicon is crystalline silicon.  
     
     
         31 . The material of  claim 22  wherein the silicon is amorphous silicon.  
     
     
         32 . The material of  claim 22  wherein the silicon is hydrogenated amorphous silicon.  
     
     
         33 . The material of  claim 22  wherein the silicon is alloyed with germanium.