Inorganic Fiber Webs and Methods of Making and Using

Abstract

Methods are disclosed in which two or more forming chambers are used to process inorganic fibers by gravity-laying methods. The methods may comprise using a first forming chamber to open inorganic fibers and using a second forming chamber to process the opened inorganic fibers, optionally to blend the opened inorganic fibers with additional inorganic fibers and/or with particulate additives, and to collect the inorganic fibers as a mat. The methods may comprise using a first forming chamber to form a first inorganic fiber layer and a second forming chamber to form a second inorganic fiber layer, and consolidating the first and second inorganic fiber layers so as to provide a multilayer gravity-laid inorganic fiber web.

What is claimed is: 
     
         1 . A multilayer inorganic fiber web comprising:
 a first gravity-laid inorganic fiber web layer of a first composition and with first and second oppositely-facing major surfaces; and,   a second gravity-laid inorganic fiber web layer of a second composition and with first and second oppositely-facing major surfaces,   wherein the first and second gravity-laid inorganic web layers are bonded together.   
     
     
         2 . The multilayer web of  claim 1  wherein the second composition is different from the first composition. 
     
     
         3 . The multilayer web of  claim 1  wherein the first and second gravity-laid inorganic fiber webs are both consolidated webs. 
     
     
         4 . The multilayer web of  claim 1  wherein the first gravity-laid inorganic fiber web layer comprises ceramic fibers and wherein the second gravity-laid inorganic fiber web layer does not comprise ceramic fibers. 
     
     
         5 . The multilayer web of  claim 4  wherein the ceramic fibers are biosoluble ceramic fibers. 
     
     
         6 . The multilayer web of  claim 4  wherein the second gravity-laid inorganic fiber web layer comprises mineral wool fibers. 
     
     
         7 . The multilayer web of  claim 4  wherein the second gravity-laid inorganic fiber web layer comprises magnesium aluminum silicate glass fibers. 
     
     
         8 . The multilayer web of  claim 4  wherein the second gravity-laid inorganic fiber web layer comprises basalt fibers. 
     
     
         9 . The multilayer web of  claim 4  wherein the second gravity-laid inorganic fiber web layer comprises organic binder and wherein the first gravity-laid inorganic fiber web layer does not comprise organic binder. 
     
     
         10 . The multilayer web of  claim 9  wherein the second gravity-laid inorganic fiber web layer comprises bicomponent organic polymeric bonding fibers. 
     
     
         11 . The multilayer web of  claim 1  wherein the first gravity-laid inorganic fiber web layer comprises an intumescent additive and wherein the second gravity-laid inorganic fiber web layer does not comprise an intumescent additive. 
     
     
         12 . The multilayer web of  claim 1  wherein at least one of the first or second gravity-laid inorganic fiber web layers comprises a blend of: inorganic fibers with a length of about 1 cm or less and inorganic fibers with a length of about 5 cm or more. 
     
     
         13 . The multilayer web of  claim 1  wherein the first and second gravity-laid inorganic web layers are bonded together by way of at least some fibers of the first web layer at the first surface of the first web layer being bonded to at least some fibers of the second web layer at the first surface of the second web layer. 
     
     
         14 . The multilayer web of  claim 1  wherein the first and second gravity-laid inorganic web layers are bonded together by way of at least some of the fibers of each web layer being needle-punched so that at least some fibers of the first web layer are entangled with at least some fibers of the second web layer. 
     
     
         15 . The multilayer web of  claim 1  wherein the first and second gravity-laid inorganic web layers are bonded together by way of at least some of the fibers of each web layer being stitch-bonded so that at least some fibers of the first web layer are stitch-bonded to at least some fibers of the second web layer. 
     
     
         16 . A fire-protective article comprising the multilayer web of  claim 1 .