Fuel container having contiguous unbonded polyacetal/polyolefin layers

Abstract

A two layer thermoplastic fuel container having a capacity of about 5 gallons or less is disclosed that includes an inner barrier layer of polyacetal resin in intimate unbonded surface-to-surface contact with an outer polyolefin layer operative to absorb impact and distribute an applied force, the two layers optionally being mechanically linked at one or more copular regions, but being otherwise capable of independent local displacement with respect to each other. Not having a bond between the layers allows them to move independently upon impact or when internal/external forces are applied. Also disclosed are methods for making these fuel containers.

1 . A fuel container comprising an inner barrier layer of polyacetal resin in intimate unbonded surface-to-surface contact with an outer polyolefin layer operative to absorb impact and distribute an applied force, the two layers optionally being mechanically linked at one or more copular regions, but being otherwise capable of independent local displacement with respect to each other, wherein the fuel container has a capacity of about 5 gallons or less.  
   
   
       2 . The fuel container according to  claim 1 , wherein the two layers are linked by one or more copular regions and wherein said copular regions occupy less than 5% of the surface area between layers.  
   
   
       3 . The fuel container according to  claim 2 , wherein the two layers are linked by one or more copular regions and wherein said copular regions occupy less than 1% of the surface area between layers.  
   
   
       4 . The fuel container according to  claim 1 , wherein said polyacetal inner layer is a polyacetal copolymer resin.  
   
   
       5 . The fuel container according to  claim 4 , wherein said polyacetal copolymer consists of a copolymer of trioxane and ethylene oxide.  
   
   
       6 . The fuel container according to  claim 4 , wherein said polyacetal copolymer consists of a copolymer of trioxane and 1,3-dioxolane.  
   
   
       7 . The fuel container according to  claim 1 , wherein said polyacetal inner layer is a polyacetal homopolymer resin.  
   
   
       8 . The fuel container according to  claim 1 , wherein said polyacetal inner layer has a thickness of from 0.005 to 0.1 inches.  
   
   
       9 . The fuel container according to  claim 8 , wherein said polyacetal inner layer has a thickness of from 0.01 to 0.08 inches.  
   
   
       10 . The fuel container according to  claim 9 , wherein said polyacetal inner layer has a thickness of from 0.015 to 0.06 inches.  
   
   
       11 . The fuel container according to  claim 1 , wherein said polyolefin outer layer is high density polyethylene (HDPE).  
   
   
       12 . The fuel container according to  claim 1 , wherein said polyolefin outer layer has a thickness of from 0.010 to 0.15 inches.  
   
   
       13 . The fuel container according to  claim 12 , wherein said polyolefin outer layer has a thickness of from 0.030 to 0.125 inches.  
   
   
       14 . The fuel container according to  claim 13 , wherein said polyolefin outer layer has a thickness of from 0.060 to 0.1 inches.  
   
   
       15 . The fuel container according to  claim 1 , wherein said container has a capacity of about 1 gallon or less.  
   
   
       16 . The fuel container according to  claim 15 , wherein said container has a capacity of about ½ gallon or less.  
   
   
       17 . The fuel container according to  claim 16 , wherein said container has a capacity of about 1 quart or less.  
   
   
       18 . A method of making a fuel container by way of blow-molding comprising: 
 (a) preparing a moldable multilayer parison comprising an inner polyacetal resin layer in intimate and direct contact with an outer polyolefin layer thereof; and    (b) blow molding the parison into the container shape, including mechanically linking the polyacetal layer and the polyolefin layer at one or more copular regions,    whereby the fuel container comprises an inner barrier layer of polyacetal resin in intimate unbonded surface-to-surface contact with an outer polyolefin layer operative to absorb impact and distribute an applied force, the two layers being mechanically linked at one or more copular regions, but being otherwise capable of independent local displacement with respect to each other, wherein the fuel container has a capacity of about 5 gallons or less.    
   
   
       19 . The fuel container according to  claim 18 , wherein said copular regions occupy less than 5% of the surface area between layers.  
   
   
       20 . The fuel container according to  claim 19 , wherein said copular regions occupy less than 1% of the surface area between layers  
   
   
       21 . The method according to  claim 18 , wherein said fuel container is prepared by the process of co-extrusion blow molding.  
   
   
       22 . The method according to  claim 18 , wherein said polyacetal inner layer is a polyacetal copolymer resin.  
   
   
       23 . The method according to  claim 22 , wherein said polyacetal copolymer consists of a copolymer of trioxane and ethylene oxide.  
   
   
       24 . The method according to  claim 22 , wherein said polyacetal copolymer consists of a copolymer of trioxane and 1,3-dioxolane.  
   
   
       25 . The method according to  claim 18 , wherein said polyacetal inner layer is a polyacetal homopolymer resin.  
   
   
       26 . The method according to  claim 18 , wherein said polyacetal is supplied to a multimanifold co-extrusion die at a melt temperature of from about 350° F. to about 375° F.  
   
   
       27 . The method according to  claim 26 , wherein said polyacetal is supplied to the die at a melt temperature of from about 355° F. to about 365° F.  
   
   
       28 . The method according to  claim 18 , wherein said polyolefin outer layer is high density polyethylene (HDPE).  
   
   
       29 . A method of making a fuel container by Co-Injection Molding comprising: 
 (a) injection molding a first resin layer in the shape of the container; and    (b) injection molding a second resin layer in intimate and direct contact with the first layer in the shape of the container, such that there is provided an inner and outer layer mechanically linked at one or more copular regions; and    wherein the inner layer is an inner barrier layer of polyacetal resin in intimate unbonded surface-to-surface contact with an outer polyolefin layer operative to absorb impact and distribute an applied force, the two layers being mechanically linked at one or more copular regions, but being otherwise capable of independent local displacement with respect to each other, wherein the fuel container has a capacity of about 5 gallons or less.    
   
   
       30 . The fuel container according to claim  37 , wherein said copular regions occupy less than 5% of the surface area between layers.  
   
   
       31 . The fuel container according to claim  38 , wherein said copular regions occupy less than 1% of the surface area between layers.