Evacuated jacket for thermal insulation and process for manufacturing the same

Abstract

An evacuated jacket for thermal insulation comprises a discontinuous or porous, organic or inorganic filling material arranged inside an envelope made with at least one multi-layer barrier sheet ( 1 ) of substantially rectangular shape, which comprises at least one polymeric or inorganic central layer ( 2 ) having barrier properties towards atmospheric gases, an upper layer ( 4 ) and a lower layer ( 3 ), both of a polymeric material. The polymeric material which forms said upper layer ( 4 ) and the polymeric material which forms said lower layer ( 3 ) of the barrier sheet ( 1 ) are mutually heat-sealable and said barrier sheet ( 1 ) is folded up so as to superimpose two opposite sides ( 5, 6 ) thereof which are welded to each other by melting said upper layer ( 4 ) at one margin ( 6 ) and said lower layer ( 3 ) at the other margin ( 5 ). The present invention also relates to a process for manufacturing said evacuated jacket for thermal insulation.

1 . An evacuated jacket for thermal insulation, comprising a discontinuous or porous, organic or inorganic filling material arranged inside an envelope made with at least one multi-layer barrier sheet ( 1 ) of substantially rectangular shape, which comprises at least one polymeric or inorganic central layer ( 2 ) having barrier properties towards atmospheric gases, an upper layer ( 4 ) and a lower layer ( 3 ), characterized in that said upper layer ( 4 ) and said lower layer ( 3 ) of the barrier sheet ( 1 ) are formed of mutually heat-sealable polymeric materials.  
     
     
         2 . An evacuated jacket according to the preceding claim, characterized in that both the polymeric material which forms said upper layer ( 4 ) and the polymeric material which forms said lower layer ( 3 ) of the barrier sheet ( 1 ) are selected in the group consisting of: polyolefines, poliacrylonitrile, polyvinylchloride and mixtures or copolymers thereof.  
     
     
         3 . An evacuated jacket according to the preceding claim, characterized in that both the upper layer ( 4 ) and the lower layer ( 3 ) of the barrier sheet are made of high density polyethylene or a copolymer thereof.  
     
     
         4 . An evacuated jacket according to any of the preceding claims, characterized in that said upper layer ( 4 ) and said lower layer ( 3 ) of the barrier sheet ( 1 ) have a thickness between 20 and 100 μm.  
     
     
         5 . An evacuated jacket according to the preceding claim, characterized in that said upper layer ( 4 ) and said lower layer ( 3 ) have a thickness of about 50 μm.  
     
     
         6 . An evacuated jacket according to any of the preceding claims, characterized in that it contains a getter material or device.  
     
     
         7 . A process for manufacturing an evacuated jacket according to one of the preceding claims, characterized in that it comprises the following steps: 
 preparing one multi-layer barrier sheet having a substantially rectangular shape comprising at least one polymeric or inorganic central layer ( 2 ) having barrier properties towards atmospheric gases, an upper layer ( 4 ) and a lower layer ( 3 ) formed of mutually heat-sealable polymeric materials;    folding up said barrier layer ( 1 ) so as to superimpose two opposite margins thereof ( 5 ,  6 ) and welding together said margins by melting said upper layer ( 4 ) at one margin ( 6 ) and said lower margin ( 3 ) at the other margin ( 5 ), obtaining an envelope with two open ends;    sealing one open end of said envelope by welding on itself an edge of the barrier sheet which is orthogonal to said margins ( 5 ,  6 );    inserting into the envelope a discontinuous or porous, inorganic Or organic filling material;    evacuating the interior of the envelope; and    sealing the other open end of the envelope by welding on itself the other edge of the barrier sheet which is orthogonal to said margins ( 5 ,  6 ).    
     
     
         8 . A process according to  claim 7  characterized in that, before the last sealing, a getter material is inserted inside the envelope.